Painted Wheels

[adsense_id=”4″]Recently there were some discussions on the Z3 message board regarding painting wheels. In response to that discussion I went through my Z3 photo collection looking for photos people may want to see in regard to wheel color and/or painting. In this first photo the owner found some aftermarket wheels that already matched the color of his car (no painting required).

Okay it’s not really painting, but chroming wheels is another way to change the look of your stock wheels. In my opinion chrome adds to the retro look of the Z3, this picture jumped out at me as I was going through my collection because the white and chrome combination looked so good.

If I owned a white Z3 (and someday I may), I would consider painting the wheels white just like this M owner has. The white on white look is fantastic (in my opinion). It reminds me of the early 80’s Porsche 944’s that apparently had a white wheel option if you got the white exterior paint.

Not sure if it’s the quality of these photos or the specific lighting in these photos, but personally I would be after a more flat white look (but that’s just me chasing my memory of the old Porsche white wheels).

Now at the other end of the spectrum (sorry couldn’t resist that pun) we have black wheels. I’m sure this look is very hard to photograph, but these photos don’t appeal to me because you can’t make out any details of the wheels.

You can see more details of the wheel in this photo. Maybe its the matching black exterior paint but this photo makes the black wheels look better than the previous photo. Notice how the dark paint makes the disc brake stand out. Some red caliper paint would really stand out.

BMW Z3 Droopy Glovebox

The factory installed glove box on my 1997 1.9 Z3 was definitely not an area that BMW decided to spend a lot of time on. After a few years the stamped plastic box began to sag in the middle under the weight of the glove box door and its contents. And who wants droopy drawers in their sports car? Here is an easy fix that will cost you about $5 and take around an hour to complete. The basic premise is to brace the top area of the glove box with a metal support, and insert sheet metal screws into the support from inside the glove box to eliminate the sagging.

You will need a stubby phillips screw driver, an awl, a drill and the use of a grinder. All of the following items were purchased from Ace Hardware:

* 2 3/16 washers

* 2 3/8 washers

* 2 number 8 x 32 1 1/4″ sheet metal screws with nuts

* 2 vinyl bushings cut to about 3/8″ in height

* 2 flip cap screw covers (many colors to choose from)

* 1 10″ x 1″ metal brace

* Loctite

It is important that you purchase the 10″ x 1″ brace at Ace Hardware unless you want to do some serious drilling. The pre-drilled holes at the ends of the brace fit over the existing screws that protrude from the bottom of the glove box. The next set of holes provide a great place to drill the holes into the glove box.

Folow the instructions in the MZ3.net article “Stopping Glovebox Rattles” to remvoe the glovebox from the car. Turn the glove box over and place the metal brace over the two existing screws coming out of the glove box. Use the awl to mark the centers of the holes that you will be drilling into the glove box. Note that the holes are offset, so use your judgement as to where to mark the centers for drilling.

Refer to the picture at right and the metal brace above. You will need to notch the brace in the center to allow for the latch of the glovebox to close. With the metal brace resting on top of the existing screws (A), outline the area to be removed from the brace for the glovebox latch (C) using a black marker. Remove the metal brace and use the grinder to remove the area you have marked. Place the brace back on the glove box and trim the notched area until the glovebox latches closed easily.

Now you are ready to drill. To avoid drilling into the glove box drawer, hold a wooden block inside the compartment near the latch where the drill bit will come through. Using a 3/16 bit, drill the marked holes into the glove box. After you finish drilling, take this opportunity to give the glovebox a thorough cleaning.

Attach the metal brace to the glove box by assembling as illustrated below.

After you have attached the metal brace and tightened the nuts firmly, add a drop of Loctite where the bolt leaves the nut. This will prevent the nut from vibrating loose. Close the caps over the screw heads and reinstall the glovebox into the car. Again refer to the the MZ3.net article “Stopping Glovebox Rattles” for instructions on reinstalling the glovebox.

1.9 Sound System Upgrade

I’ve wanted to upgrade my Z3 sound system for a while. I found that the stock system simply wasn’t good enough to support a convertible. I started looking around and came to MZ3.net and looked at Robert’s 1.9 (Non-HK) Stereo Upgrade. This article helped me A LOT during my search for a better sound system. Now was the time to see where I should get it done. The first place I went to was Audio Excellence. It looked very professional and some of my friends suggested it. I also went to Audio Extreme and Sound Advice but out of the three Audio Excellence was at the top.

I wanted to upgrade the front speakers first. I looked at JL Audio and was impressed by their clarity. I also wanted to get larger speakers and I ended up with 6 ½” JL Audio XR650-CS (with tweeters and crossovers).

I realized that I needed a much better amplifier because the stock amp (non HK) was pushing around 20-25 watts per channel. I decided to go with the Orion Cobalt CS200.4 (Which later changed to the CS500.5) I was also looking at the Alpine V12 models but their prices were too high.

Audio Excellence told me that I might be able to put 5 ½” in the rear to replace the 4″ speakers. This luckily didn’t work out and I got a free pair of 4″ speakers.

Installation

The installation took around 7 hours. I took it in at 9 am at brought it home at about 4 pm. I was very happy with this installation because everything seemed to go my way. First they tried fitting the 5 ½” in the rear. These didn’t fit so they decided to leave the stock 3 ½” in there. The install for the tweeters and XR650-CS went fine but the amp didn’t. They put the CS200.4 in and it blew my rear speakers due to a short. They gave me a CS500.5 instead and replaced my rear speakers with JL Audio XR400-CX.

So the price of the JL Audio XR525-CX was cut from the bill and I upgraded to 4″ rear speakers and a 5-channel amp for free! Total cost was about $750.

Turning up the new system loud would guarantee to make your ears bleed. All that was coming out of it was highs. There was more bass than stock but it wasn’t enough. I decided to get a subwoofer.

The first place I wanted to put one was in the trunk. I planned on putting a 10″ sub opposite the side of the trunk with the CD Changer. Audio Excellence told me that in front of the trunk was a metal wall separating the cabin from it. Porting to the cabin would have to go through the boot of the convertible and with the top down bass would be nonexistent. I also wasn’t too happy with the idea of cutting a whole in my BMW.

My other idea was to put an 8″ or a 10″ in the spot where the HK Sub is. My idea was similar to where the Dodge Viper has its subwoofer. Audio Excellence looked at the area (where my storage compartments are) and told me that it would mess with the structural integrity of the car because the roll bars came down into there. I decided this idea was a no-go also.

They came up with an idea that I was trying to avoid. They wanted to put the sub below the dash on the passenger side. They did this to a member of N’Sync’s Superformance Shelby Cobra. Even though I was disappointed because doing this would take up legroom I decided to go along with this idea.

They ended up making a custom box and putting a JL Audio 8W3 subwoofer in my car. This ended up costing $350 and took about 13 hours (11 hours one day, 2 hours the next). It turned out well and sounds amazing!

Is it worth it?

Yes, I think that it was worth it. I love being able to hear music without distortion at 60mph with the top down. It turned out to be much cheaper than I thought and sound better than I imagined. Even though the subwoofer installation took forever I think that having that extra bass really makes the sound fuller.

Pros – Awesome Sound, Not very expensive

Cons – Lost passenger legroom, No more stock look

Cost – About $1,100

1.9 to M Conversion

Why I did it:

I am poor, but I love the M Roadster. You may know me as WannaM on the message boards. The M’s full, muscular rear end is much more masculine and finished looking than the other Z’s in my humble opinion, but alas, I can’t afford an M. I think the 1.9 liter’s rear end looks dilapidated and unfinished. However, as background, I rent a two-car garage and live in the other half. In other words, all of my money goes to my car, and I live like a bum. How many other people can claim such loyalty to a car? In addition, I do upgrades as I have money instead of just picking the ones I want and doing them. Robert Leidy’s beautiful roadster was the target template for my car as I have a 1996 Arctic Silver 1.9. What finally convinced me was that the rear track width on the 1.9 and M roadster are nearly identical, unlike the 2.5 and 2.8 which are noticeably wider, especially with M rims on. Thus, the conversion compatibility was the decision maker.

What it cost:

I tried to keep the costs down by selling the old parts and buying from salvage yards. The two biggest problems are 1) it takes a long time and patience to find the parts from salvage yards and 2) some of the parts are damaged and replacing/repairing ends up costing more than new parts. In the end, I had hoped that I could keep costs very low. I was wrong.

Process:

The upgrade is pretty simple (but intense). I contact the Mazjun’s who had upgraded their 1.9 to a widebody format like a 2.8 after a minor accident. The reality is that a LOT of parts are only slightly different but need to be completely replaced. I searched for most of the parts on the newsgroups, ebay, and the salvage yards. The following parts are needed for a (1996) full exterior conversion to an M:

* Both Bumper covers

* Both rocker panels

* Both quarter panels

* Gas filler flap

* Both Rear plastic wheel linings

* Roll bar/hoops

* Both side mirrors

* Both hood gills

* Trunk Lid

* Electric trunk lock mechanism

* Rear trunk license plate assembly

* License plate lights

* Chrome trunk button surround

* 4 Satin chrome M wheels

* 4 new tires

* Custom spliced exhaust (picture included, and it’s the best I could do without jacking the car up)

* Two new mufflers

Other work:

Removing the black plastic covering on the A pillars/windshield frame. For cost sakes, I did not replace the head/taillights with clear lenses, nor replace the side mirrors. You must extend the license plate lights wiring from the rear bumper to the trunk lid. For this, I simply used wiring I bought from Home Depot.

Problems:

Painting is expensive. I found a great shop in Lincoln Park (Chicago), European Auto, that matched the paint wonderfully without “blending.” The con is that it is relatively expensive and takes a while to mix a good match, but I would recommend this shop to anyone getting any type of paint job. I also noticed during the re-assembly, that the parts that were “used/salvaged” definitely exhibited “fit” problems. Using new parts is certainly the preferred choice if you can afford it. Was it worth it?? Since costs started to get out of hand, I’m not sure if it’s worth it. If you have access to cheap parts and a lot of time, the look is definitely cool, but car novices might not even notice the difference. I like the new look though. I only wish it were a real M. Perhaps BMW might realize I’m their biggest enthusiast and donate another car for me to modify.

European Auto Ltd

2547 N Lincoln Ave

Chicago, IL 60614-2313

Phone: (773) 348-5440

I had major problems with the trunk locking mechanism. I wasn’t sure how the reverse placement of the trunk button would affect the lock. It was minimal work to refit really, BUT, in the process, I could not figure out how to reuse the electric locking control, thus I need to use the key to lock/unlock the trunk.

Visible Discrepancies with the M:

The interior had been modified over the years to a more chrome finish like many others. The noticeable differences inside are the lack of leather wrapped dash, M sport seats, no Oil Temp/Analog Clock/Oil Pressure gauges, power roof, rear view mirror, etc. I do have a sprinkling of LeatherZ products which are awesome. The exterior lacks the M side mirrors (which irks me a little each time), fit-and-finish of the new panels is not as great as my original stock 1.9. Also, the lights have the original amber, not the later “clear” look (but I considered Robert Leidy’s as a template). I also have not yet put the plastic wheel well linings in as the pictures show.

Future:

As I said, this project really put me in the poor house — literally. Towards the end, I became a prostitute and even tried soliciting companies to donate the parts to me if I put a decal on my car. Semi-happily, no one took me up on my offer. The things that I would like most to add eventually would be:

* Any type of windscreen

* Any type of supercharger

* Any Spring lowering kit

* Additional leather treatment to the interior

In retrospect, it might’ve been easier to sell my car and put the upgrade money into getting a used 2.8 or something, but I had no idea how few Z3 parts would’ve been on the salvage market and how expensive dealership parts would’ve been. Live and learn – I suppose. Until then, I believe that I have only 1 of 2 Z3 1.9’s with a widebody conversion, the only 1.9 with M body technics, and – in the spirit of making the MZ3 an actual vehicle – a real MZ3.

If I had one wish right now, I would like to add a supercharger, as I have been attending many of the local import tuner shows. My car gets a lot of attention, but on the drag strips, it gets quite embarrassed.

Pros: Looks great… almost like an M.

Cons: Unjustifiable cost, car is out-of-commission during upgrade, is not completely a DIY project.

BMW Z3 Wacky Gas Gauge

One of the most consistent failures in the BMW Z3 is the gas gauge. I’ve heard different excuses as to why the gas gauge fails, but rather than pretend to be an engineer or parts inspector let me just share with you some observations I have made regarding my wacky gas gauge.

Let me start by saying I never had a problem during my first year of ownership. But others were having problems during that time so I heard a lot of speculation regarding what caused the failure and I got to see what BMW’s fix was for those under warranty. I can almost pin-point the exact time mine started acting up. I was refueling and for some reason, when the gas pumped stopped I squeezed the pump trigger one more time. I don’t know why I did it, I had been warned not to yet for some reason I did it.

It was long afterwards I saw the gas gauge do its first flip-flop dance between empty and full. The error was initially intermittent, but over time it has become very consistent. Now mine always (and I do mean always) does its dance between empty and full right after I refuel. This will continue until I travel roughly 30 miles, I’ve never noticed the problem beyond the first 30 miles of a tank. Couple months ago I decided to try an experiment, instead of refilling until the pump clicks off I started buying my gas in $10 increments (never filling the tank all the way). The gas gauge never did its dance during the 4 or 5 tanks that I did the $10 thing. So at least in my case, these observations seem to back up the theory that the failure is related to the sending unit. I’ve learned to live with it, but learn from my experiences and resist the urge to squeeze that gas pump trigger again once it clicks off.

I have made the decision to live with it rather than have it fixed because I am not comfortable with the “fix”. To get to the sending unit BMW has to cut the carpet behind the passenger seat. Then they have to hook a hose and drain the gas tank (hopefully without leaving your interior smelling like gasoline). If you look behind the right hand seat you can see a seam in the carpet, this is where they will make the cut. Once the sending unit is replaced the carpet is glued back down. Sounds simple enough but I have seen more than one Z3 after this fix where the carpet flap has come unglued and ends up looking like a bad toupee. It also appears the new sending units are not necessarily any more reliable than the original ones.

I’ve owned my M roadster over four years now and my refueling habits are fairly consistent. I’ll usually refuel before the low fuel light comes on, if I push it and the low fuel light comes on then pull off at the next available gas station. I use my trip odometer to measure distance on a tankful, and on average it usually says around 240 miles since my last refueling and it will take around 12 gallons to fill the tank back up.

One day after work I pushed it a too far, the engine sputtered then quit. I zig-zagged a little and got another second or two of runtime before it quit for good. Luckily I was going downhill at the time so I managed to coast into the gas station and right up to the pump. I got lucky, and this provided me with an opportunity. I now know it takes 13.3 gallons to fill a completely empty tank. I started taking notes after that and refilling at different points on my gas gauge. It takes 8.9 gallons to fill a tank that my gauge indicates is half empty. 12.3 gallons to fill a tank right after the low fuel light comes on. I will continue to take measurements at various points on my fuel gauge and update this page.

One last final note: Remember that my fuel gauge has problems so my measurements may not be typical of most Z3s.

Valentine-1 Installation

In search for a power source to wire up my V-1, I found the article “Finding power in your center console” by Vince Parsons. Sure enough, I found the connector he describes, and started thinking how to run the wire and stuff. Then I realized that the connector that’s part of the wiring kit that comes with V-1 is the exact size of the tabs next to the ASC button on the console in my ’97 1.9 Z3. I tried it, and it fits perfectly! I used some glue to stick it from the inside.

Initially I was thinking of hiding the wire of the V-1, but then I realized that, since I keep my V-1 on the dashboard in the center of my windshield, in case I get stopped by police it would be inconvinient for me to disconnect the wire from the side of the radar detector. With my setup, all I need to do is unplug the wire from the connector in the console, then grab the V-1 from the dash board (it sits there attached with velcro) and throw it under the seat. And more importantly, the connector is very neatly mounted in the center console.

LeatherZ Shift Knob

LeatherZ just keeps coming out with new ideas and products for the Z3. When I first heard that LeatherZ could recover the stock BMW shift knob with their higher quality leather, I knew I would want to have one. After thinking over the additional color options LeatherZ offered I decided to try something different and go with a two-tone dark gray and black. LeatherZ’s dark gray is an almost perfect match to the dark gray on the seats in my 1998 M roadster, and it’s also a great complement to my LeatherZ covered armrest.

Removing the stock Z3 shift knob is fairly easy, the M series has one additional step due to the lighted face. Basically all you have to do is pull it off. With the M series you’ll want to get under the shift boot first and disconnect the two wire plug. Once I removed my shift knob I mailed it to LeatherZ and waited for its return. I went about a week without a shift knob, surprisingly it wasn’t that big a hindrance to shift without the knob in place.

LeatherZ provided a couple interesting pictures (1, 2) of the shift knob during the recovering process. You can see how the lighted knob is internally wired in these pictures. Once LeatherZ completed the upgrade they mailed the shift knob back to me. Reinstallation was fairly easy, I threaded the 2 wire connector plug through the shift boot and plugged it in. Then noted the “U” shaped pattern to the receiving end of the shift lever, aligned the shift knob and pushed it back down (adding a whack with the heal of my hand for good measure).

I’ve heard of some Z3 owners having shift knobs come off while driving. I wouldn’t recommend using glue but maybe some lock-tight inside the “U” indentation would provide some additional holding strength for those that require it.

LeatherZ Pricing Options:

If LeatherZ provides the shift knob (new):

1. Black, Beige, Dark Gray, or Tanin Red monochromatic or 2-tone Leather Shift Knob – $100.00.

2. Illuminated M-style Leather Shift Knob in Black, Beige, Dark Gray, or Tanin Red monochromatic or 2-tone Leather – $135.00

3. Illuminated M-style Leather Shift Knob in Black, Beige, Dark Gray, or Tanin Red monochromatic or 2-tone Leather with Corrected Amber (not red) LEDs – $165.00

If customer provides shift knob:

1. Black, Beige, Dark Gray, or Tanin Red monochromatic or 2-tone Leather Shift Knob – $40.00.

2. Illuminated M-style Leather Shift Knob in Black, Beige, Dark Gray, or Tanin Red monochromatic or 2-tone Leather – $75.00

3. Illuminated M-style Leather Shift Knob in Black, Beige, Dark Gray, or Tanin Red monochromatic or 2-tone Leather with Corrected Amber (not red) LEDs – $105.00

In most cases the customer can specifiy a different shift pattern insert at no additional charge.

LeatherZ is also planning to carry BMW brushed and matte chrome (real metal) shift knobs that also illuminate. These knobs are shorter than stock and should be similar to the one in this article.

How to Build a Z3 Dual Arm Rest

With a trip to your local BMW dealership for one $25.00 part and a visit to your local Home Depot for another $20.00 in hardware you can construct this dual arm rest (uncovered) for your Z3 or ///M with simple hand tools.

This arm rest was inspired by my wife Sharon. I would be the driver, she would be the passenger and as I would raise my arm to shift she would steal the arm rest or as I would raise my arm to steer she would steal the arm rest. I decided to invent my Z3 dual arm rest. In doing so I have also come to learn that it is now possible to rest my elbow on the new arm rest while steering. This is not really possible with the OEM arm rest as it is to far away. I’m 6’4″ with long arms and people with shorter arms that have tested the dual arm rest prefer this arm position. So many thanks to my wife Sharon.

I have tried many different variations on this project and what I give you now is the best I have found to work. You have a few choices to make, such as, color of hardware and felt, painting it or dipping it and whether it is going to be leather covered by Jon Maddux at www.leatherz.com. It’s REALLY not that complicated once you read through the instructions and get a better understanding of what I’m talking about. My personal choice was brass hardware with a black felt covered forward bumper support catch that was dipped in black Plastic coat. Then sent to Jon M. at www.leatherz.com for matching tan cover with the word Roadster embroidered on it.

Generally speaking the parts will cost you anywhere from $34.00 to $42.00 depending on if you get a discount at BMW dealership, the choices you make regarding felt and plastic dip, sales taxes and what you may already have available to you. The tools on the other hand could add up to $150.00 or more. Then if you are sending it on to leatherz to be covered more $. Yeah, but it’s your “baby” right.

You will need to remove the cupholder assembly from your Z. The one in your car now is not the one we will be working on but will be replaced by the new . Note: there may be cases where the one in car is the one to be retrofitted. Anyway this is no big deal. We are talking about removing one screw or one nut and bolt. OK it is a tight spot but you can do it. There is even a great article on the www. leatherz.com site for removing the cupholder assembly. See Rachels excellent cupholder assembly instructions there.

If you are not having this leather covered (why in the world aren’t you) you may want to spray paint the top ring of the rivet nut and possibly both hinges black to match the lids. If you are doing an installation WITHOUT the rivet nut the top nut and lock washer should be painted or better yet plastic dipped black to match lids and prevent clothes catching on it. This nut REALLY bothers me especially if it’s going to be leather covered so I wish you would reconsider and do the rivet nut option.

Collecting the Parts

Start by collecting all parts and tools you will need. Here is the list.

1. Cup holder assembly BMW part # 82-11-1-469-516

2. 1 pair of 2″x 3/4″ hinges. National or simuilar with removeable pin in brass or silver (your choice). Home Depot # 218-995 (brass) # 218-979 (silver)

3. 1-Grip clip. Home Depot # 201-739, 4 to a package, only need one.

4. 1-7/8″ dia. bumper. Home Depot 3 524-062, 4 to a package,only need one. Black if you can find it but I couldn’t.

5. 1- 8″x 11″ sheet of felt (or less) with sticky back. Color of your choice. I got mine at Rag Shop in black, two sheets to a package. Home Depot -Felt Gard # 423-234. Choice of biege or brown in medium and heavy grade. I suggest medium.

6. Opinional. Plastic dip. Available at Home Depot in red, yellow and blue. I used black and got mine at local hardware and also available from Harbor Freight. This is to coat brown bumper black or cover exposed nut and lock washer in non- rivet, non-covered lid. Note: you can get away without plastic dip if you chose to leave bumper brown or paint it. But you should use it on non-nut rivet installations.

7. 1-Machine screw (1 1/2″ 10-24 thread) slotted round head in brass or silver (your choice)

8. 3- 10-24 nuts and 3- #10 lock washers (color match)

9. Loc-tite or Permatex nut lock (permanent type) only for non rivet nut installations. READ ON FOR MORE INFO ON THIS TYPE INSTALLATION.

10. Styrofoam ( the softer white that comes with everything. Not the harder flower arrangement stuff.)

***Part #’s are for reference only. Please make sure you get what is described.

Tools

* Drill

* 3/16″ and 17/64″ possibly 11/64″ drill bits

* Normal rivet gun

* package of 3/16″ with 1/4″ bite aluminum rivets

* *Rivet nut gun – This can be gotten via Harbor Freight for $20.00. It is a cheap(er) version of one that is available at Napa car stores for $114.00. Both come with the 10-24 nut rivet you will use.

* Razor knife

* Scissors

* Hacksaw with blade

For cupholder assembly removeal and installation:

* Allen wrench

* Metric or adjustable wrench

* I’ll tell you how to do it without this tool but it is much better with nut rivet!

Let’s Make It

DISCLAIMER: The writer of this article assumes no responsibility what-so-ever for this armrest. It is given to you as a do- it- yourself project and you and you alone assume ALL responsibility for it’s construction, installation and any possible damage to your vehicle in connection with it. Also note that it may be unwise or illegal to obstruct the hand/emergency brake. Again you and you alone bear full responsibility. READ ALL INSTRUCTIONS THOROUGHLY BEFORE PROCEEDING WITH THIS PROJECT.

First if your OEM arm rest has no metal rod in back for the rear lid, has only little rubber bumpers without plastic surrounding them and a rubber mat in storage compartment instead of nice soft material you have the “old style”, pre-1997, and I would highly recommend you use the new cupholder for this job. For everyone else why not use the new cupholder anyway since it’s unscratched and not in the car. Yes, you will have to remove the cupholder assembly in the car and replace with the hinged one you’ll make. I see no way to drill, align and rivet on the assembly while still in the car. It’s only one screw or one nut and bolt.

OK, Let’s begin to make YOUR Z3 dual arm rest.

If you are going to dip or paint the bumper stop DO IT NOW! Screw in 1 1/2″x 10-24 machine screw through bumper until it’s recessed under the opening and flush with bumper base. Bumper is not threaded so this will require a little force. Give bumper 2 coats of dip or paint. Try to keep dip off threads. Let dry overnight. Take lids off new assembly (un-hook o-rings). The lids in your car now will replace these on this side of cupholder assembly LATER. Remove with either a hacksaw or razor knife the lid latch tabs on both lids. Cutoff flush with lid side.

PUTTING ON HINGES

Pull the pin out of one of the hinges. Get some seperation using putty knife then use wide blade screwdriver to pry out. Align 2 barrel half with the back edge of assembly, get it lined up with lid and even with top edge. Mark holes and drill 3/16″ holes. Clean off any drilled material. Note: Line up back lid (SMALLER ONE WITH BOTH CORNERS CUT OUT) with outside edge of assembly. This gives a nice space between old and new lids. Line up hinge on lid and back of assembly. Make sure edge of hinge is even with both lid edge and assembly edge. This is very important to understand, pay close attention to this picture. First visualize that the back lid is on the top left hand side of the assembly (where I made the pen marking.) You need to line up the lid with that side in order to get space between the two armrests. Now you also need to align the hinge halfs. One on back lid and one on assembly. Take note that this hinge half is NOT centered in that assembly space so we can create that needed spacing BUT it will be centered to the matching other half of hinge. We do that by holding up the FULL hinge with lid on assembly and marking sides of top and bottom hinge. Now one more thing. When you get set to mark holes you line up hinge half with edge of assembly (this case) or in next case edge of lid. This is the model you follow for each hinge. VERY IMPORTANT!

Get rivet gun loaded with 3/16 rivet, place hinge over holes and rivet. Keep it level and flush (both assembly edge and hinge edge are flush.) **Please note these rivets touch the inside wall of the assembly when first inserted, pushing the rivet head away from hinge. With a light squeeze take up on the rivet so that it gets flush with hinge and only then finish snapping rivet. Take other 1 barrel half of that hinge and do the same to the back (2 arched cut outs) of rear (smaller) lid. Be careful to line up hinges and keep hinge and lid edges level and flush with each other

Follow the same proceedure. Remove pin from second hinge and use the 1 barrel half for the front (non arched cut out side) of rear (smaller) lid . Continue on by putting the 2 barrel half on the back (non sloped end) of the forward lid. Again be careful to line up hinges with each other and have hinge edge with lid edge and keep centered. Remember to clean off any excess drilling material. *SMALLER BACK LID SHOULD NOW HAVE A 1 BARREL HALF OF HINGE ON BOTH SIDES.

Next Step

This next step is for rivet nut installation ONLY! – Hole for and installation of nut rivet in lid

Drill 7/64″ hole in the front of front lid (large lid arch cutouts on sides) at this exact location (see picture). Hole is on the OPPOSITE side of where the arch cutout is. That is the driver side of armrest. Look at lid and you will see where rounded edge ends and flat top begins a straight line appears. Pencil (red in picture) a straight line on top of it. Do this on front edge and side edge. From front line measure in 3/8″ and place a mark and from side (non-arched side) measure in 5/8″ and place a mark. Drill a 17/64″ hole where marks meet. Clean away any drilling material. Load up rivet nut gun with 10/24 rivet nut and insert into hole, (put 10-24 nut on thread of arbor as block) squeeze nut in place. Note: I stripped 2 rivet nuts. (cheap rivet nuts??) The theaded arbor on rivet nut gun pulled right through. I suggest you thread arbor all the way through rivet nut and place a 10-24 nut on arbor thread to act as a block so arbor can not pull through. Be gentle but make sure nut is firmly in place. Feel and touch sort of thing!

This next step is for those NOT using rivet nut. – Hole for machine screw with nut on lid

Dril1 3/16″ hole in the front of front lid (large lid arch cutouts on sides) at this exact location (see picture). Hole is on the OPPOSITE side of where the arch cutout is. That is the driver side of armrest. Look at lid and you will see where rounded edge ends and flat top begins a straight line appears. Pencil (red in picture) a straight line on top of it. Do this on front edge and side edge. From front line measure in 3/8″ and place a mark and from side (non-arched side) measure in 5/8″ and place a mark. Drill a 3/16″ hole where marks meet. Note: If you have a 10-24 tap drill a 11/64″ hole instead and tap it. This will add some strength.

Felt and Grip:

Place grip onto felt and trace width of grip. Add 1/16″ to 1/8″ when you cut felt with scissors. I found it better to use one continuous strip from inside grip from bolt hole around both loops and back to other side of bolt hole (approx. 7″x 1/2″ ). Leave hole uncovered. Trace open sides (outside diameter) to exact size. Flip over grip and do other side. This makes a “butterfly” shape. One for each side. DO NOT COVER YET! Now place the grip on the Styrofoam and push grip into it to fill holes. My piece of foam was 1/4″ thick and I placed on ground and hammered on block of wood. Did this twice. This filled the cavities in grip. Cut off any extra so foam is flush with sides of grip.

Next Step

Bumper support catch for nut rivet installation:

If you have not done so already, remember dipping, thread the 1 1/2″ 10-24 machine screw through the bumper. After screw is all the way into the bumper ( screw head is recessed in bumper) put screw through hole in grip from the inside to the outside. Push bumper to be flush with grip metal. This can be very tight. You need to bend the grip a bit for bumper to get seated and you also need that bend plus a little more so grip guides onto hand brake and does not clamp it. It should have just some grip. This is a good time to test it on your hand brake. OK, now put on a #10 lock washer and 10-24 nut and tighten. Put another 10-24 nut and #10 lock washer onto screw about 3/4″ down. This is then screwed into the nut rivet on the front lid. The nut down the threads is to adjust height of arm rest to match other and then tightened to lock in place. ** You do not send this to Jon M. Put aside with your hinge pins. Remember where you put them! You can install this when they are returned covered.

Bumper support catch for non-nut rivet installation:

If you have not done so already, remember dipping, thread the 1 1/2″ 10-24 machine screw through the bumper. After screw is all the way into the bumper ( screw head is recessed in bumper) put screw through hole in grip from the inside to the outside. Push bumper to be flush with grip metal. This can be very tight. You need to bend the grip a bit for bumper to get seated and you also need that bend plus a little more so grip guides onto hand brake and does not clamp it. It should have just some grip. This is a good time to test it on your hand brake. OK, now put on a #10 lock washer and 10-24 nut and tighten. Put another 10-24 nut and #10 lock washer onto screw about 3/4″ down. This is then screwed (if tapped) or put through hole on the front lid. The nut down the threads is to adjust height of arm rest to match other and then tightened to lock in place. If there is extra screw protruding out top cut of with hacksaw and grind /sand. Use permanant lock thread compound on top nut and thread to help prevent it coming off. If you are not and perhaps even if you are sending lids to be covered I’d suggest you use plastic dip on top nut. Tape around it leaving a little hole cutout enough for dip to attach to lid and then coat nut. Let dry and razor cut dip in circle shape. If you are sending this to Jon M for leather covering YOU MUST SENT IT ATTACHED WITH LIDS. He will cover over that nut and washer.

CONGRATULATIONS! YOU ARE DONE.

Well I don’t know about you put but I sure would want to test this out in my Z. It takes minutes to exchange the cupholder assembly in your car PROVIDED you take your time AND do not drop the nut into the well. Go to www. leatherz.com and read Rachels how to install cupholder assembly. My first experience in removing the assembly I encounter “old style” anchor screw (see picture in extra picture section) that just keep on turning and turning. Finally I lifted up on back of unit and forced it up. New style gives bolt and nylon lined nut. That nut is what you DON’T want to drop. It’s a tight fit but I haven’t dropped one yet. I would suggest to you, DO NOT put on the nut for testing out your new dual armrest. Just the bolt in hole and tabs in front will be OK for now. Plus nylon lined nuts are meant to be screwed on ONCE. Have Fun!

Final notes:

You need to talk to Jon Maddux concerning filling the front corner. Originally I had all 4 corners filled with Styrofoam. When Jon went to cover it his glue dissolved the Styrofoam. Jon made up wood corners for my arm rest and covered it. This was alot of work for Jon and also caused some “stacking” problems with the leather. We feel it is best if only the front corner is filled. The back two you don’t see and the other front lids back corner is on the side facing the other arm rest and will also be unnoticed. Besides Jon does great work on the regular corners and it may well look fine with out ANY corners being filled.

When you put lids on assembly for “final” time push pins in all the way. this takes out some play in them. This is a little tough if assembly is in car but I use a pair of wide channel locks and squeeze pin in WHILE supporting lid and hinge with my other hand. You will find it is also a little harder now that it is leather covered. You will also notice arm rest unit is less wobbly. A putty knife blade will seperate pin from barrel enough to get a wide blade screw driver in that space to remove pins.

1.9 “Fogged” Airbox Modification

Pros: Increased Performance, Proven Results, Retains Stock Airfilter
Cons: The stock airbox is expensive to replace, so don’t mess up
Cost: Roughly $20, and 3 to 4 hours of your time

In the year and a half since I first posted the DIY instructions to modify the M44 Z3s airbox I’ve found that I get the same sorts of questions. I figured a document that tied all the info together would help me and those also interested in the modification. This primarily deals with the Fogged Airbox mod for the M44 but also talks about how the fuel injection system on the Z3s works as well as alternate intake products that are available and my thoughts on them. The instructions are slightly updated from my original plans to make assembly easier and to add an optional safety step.

Engine and Fuel Injection:

The fuel injection in the Z3s is a mass air fuel metering system. What this means is your car directly measures the weight of the air being draw into your engine and injects an appropriate weight of fuel (in the ratio of 14.7 parts air to each part of fuel) which it then ignites through your ignition system. Under cruising conditions and light acceleration your cars computer (DME) uses feedback from the oxygen (O2) sensors to fine tune the mixture.

The DME measures the weight of the air using a sensor called the Hot Film Meter. (HFM) The HFM is basically a film through which a current is passed to heat it. If you were to look at the inside of your HFM you will see that the film is very small and it actually only samples a small fraction of the air that passes through the meter. By measuring the temperature change of the film (and knowing the intake air temperature) the DME is able to calculate the mass (weight) of air that is flowing over the film. It can then calculate the total mass of air flowing through the HFM. This works if the airflow through the meter is smooth and evenly distributed, in other words laminar flow. The DME then uses this to determine how much fuel needs to be injected to keep the AFR at 14.7/1, also called Lambda=1. An AFR of 14.7/1 results in the most complete combustion of your fuel which gives you the least emissions. If an engine is running rich OR lean (more or less fuel to air) the engines emissions will increase. At full throttle the DME runs the engine richer for more power.

Now a key point… if you increase the airflow into your engine, the DME will measure it using the HFM (assuming smooth airflow) and will increase the fuel injected to compensate. The DME must do this or your engine would run leaner which would increase emissions. If you increase the amount of air, to keep the ratio between air and fuel at 14.7/1, the DME must add more fuel. If you increase airflow and burn more fuel you have increased your power output.

Problem:

As delivered from BMW the M44 engine in the Z3s really is not as rev happy as say the engine in a Miata. Above 5000 rpm the power feels like it has reached a plateau and there isn’t much more to be gained by revving the engine higher. The reason for this is because up high your engine’s ability to breathe is being restricted. I wanted to see if I could correct this and verify an improvement.

After looking into the intake systems that were on the market or known to be ‘in the works,’ I determined that there was nothing out there that I would put on my car. The following are a few of the setups I found and some of my reasons for rejecting them:

Drop in K&N filter ($40): in my opinion, K&N filters do not filter as well as your stock paper filter. I will not put one on my car. Your filter is the first and only line of defense against letting dirt into your engine. The K&N is made from an oiled cotton gauze, if the oil dries out the ‘filter’ basically stops all filtering. I have heard it said that when a K&N filter gets wet the water can ‘wash’ the previously filtered dirt right through it and into your engine. The person who told me this raced motorcycles and said that when he switched from K&Ns back to paper filters his engines lasted much longer between rebuilds. Lastly, Greg Hudson had performed dyno tests comparing a new stock paper filter against a new drop in K&N filter… the result was a LOSS of power with the K&N. That demonstrates that the paper filter isn’t what is limiting airflow as the paper filter has a huge amount of surface area for the size of our engine. Swapping filters does nothing to address the real source of restriction in your intake.

K&N Filtercharger cone filter ($149): Has a lot of problems. It has the same filtering concerns as the drop in filter and the rest of the setup adds a few more problems. The cone filter can suck in hot radiator air which will hurt performance. This is because cooler air is denser air (heavier), the more air weight you can get into your engine the more fuel will be injected and the more power you will get out of your engine. The circular shield that some sell might help a little but it will also increase restriction as it blocks the filter somewhat. It still doesn’t get all that great of a source of cold air either. As with most other cone setups the tube that connects the filter to the HFM changes diameter at the cone filter and at the HFM. Those ‘adapters’ are not a good idea. When they increase or decrease in size it will cause turbulence and restrictions in the airflow. For the HFM to meter the air weight properly it needs a smooth flow of air through it. The connecting tube changes size right at the start of the HFM, this could cause turbulence which would result in improper metering by the HFM. If the HFM isn’t able to properly measure the airflow into the engine the DME is going to be injecting the wrong amount of fuel. This will keep the engine from running optimally and won’t be making the power it should. Additionally, the filter is right in front of the HFM and the airflow doesn’t have much space to ‘settle down’ so it will still be turbulent from passing through the filter itself when it hits the HFM. There will be more on this later.

Art of ROAR cone filter (~$200): Mostly the same problems as the K&N setup above.

ECIS (~$200, when available): Uses a K&N cone filter so it has all the same filtering concerns and most of the other problems except it has a shield behind/besides the filter to block off the filter from the rest of the engine compartment to help with the heat problems.

Dinan Cold air intake ($299): uses a K&N cone filter so it has all the same filtering concerns. It positions the filter behind your foglight to avoid the hot engine air problem but exposes it to more water. Has the same type of ‘adapters’ and the problems they can cause that all the above cone filter setups share.

What I was looking for was a setup that kept the paper filter (they filter well.. even when wet) that had a smooth airflow to the HFM for proper metering, and had a good source of cold air but that allowed the engine to breathe better.

Factory airbox setup:

On the stock M44 airbox the air intake is in a snorkel between the passenger side headlight and the edge of the radiator. The snorkel has a fairly narrow opening which may limit airflow somewhat plus it isn’t in a direct path of air, the hood support blocks it somewhat. From the snorkel the air flows through a 2 5/8″s insulated hose over the top of the radiator then down the other side where it connects to a plastic funnel on the airbox itself. Each turn causes restrictions.That funnel has a 1 3/4″ opening into the airbox itself and is ,IMO, the biggest source of restriction in the intake.

After the air is inside the airbox it has a good amount of area to expand to evenly pass through the filter then changes over to the HFM as BMW designed for proper air metering.

The solution… aka the ‘Fogged Airbox’:

It increases the air intake hose into the airbox to a 4″ diameter hose. That is about a 700% increase in surface area for air to flow through easier. The setup grabs its air from behind the foglight for a good source of cold air. It keeps the paper filter for maximum engine safety and the flow to the HFM is exactly as BMW designed it. In my opinion, it addresses the real problems with the factory airbox and doesn’t create any additional problems like the other setups do. It costs around $20 and takes about 3-4 hours or so to build and install.

Testing, Does it work?:

Instead of using formulas and/or a flow bench I tested the best way possible, the actual DME measured airflow into my engine. This is the ideal way to test because if your intake/engine has a bigger restriction elsewhere the formula/flow bench methods will give you misleading numbers that won’t be realized in the real world.

As was mentioned above the DME in the Z3s has a hot film sensor to calculate the actual mass (weight) of the air flowing across it based on the temperature of the film. The cooler the film is the more air mass that has passed over it. If the airflow is smooth through the HFM it will be metered properly. From this and a few other sensors the DME can calculate the mass of the air being taken into the engine. In other words, your DME knows exactly what the airflow is… all I need to do is have the DME tell me that information on before/after runs and compare the two.

Getting that data is actually very easy, provided you have the proper tools. OBDTOOL plugs into the OBDII port on your car and can grab data directly from the DME. For this test I need to grab airflow (expressed as pounds per minute) and engine RPM and log that, in real time, to a file.

Grabbing the data is easy. You set OBDTOOL to log the data to a file, drive at about 1000rpm in second or third, then just floor it till redline. When you are logging two data points (airflow + RPM) OBDTOOL is able to receive 2-3 updates per second. To get more data points (for more accurate airflow curves) I made multiple runs and merged the data points together. The higher the gear you are in the more data points you receive as well.

For the first set of data I made 3 runs with my car in its normal modified state. That includes the Fogged airbox , a +3mm big bore throttle body and a Remus exhaust. My car is a ’96 without traction control so it doesn’t have the secondary throttle body in the air stream.

Since I’m interested in just the effect of the airbox mod that is all I changed for the second set of runs.

There is one slight problem though… I can’t get my airbox back to exactly stock as I modified my personal airbox. The factory stock setup has that 1 3/4″ diameter inlet into the airbox which is the largest source of the restriction in the intake system. So I made a 4″ diameter plate (size of the Fogged’ airbox inlet) that has a 1 3/4″ hole in the center to simulate having the stock inlet in the airbox. This plate fits right in front of the rodent screen on my inlet and is held in place by it with tape around the outside edges to seal better. Because the airflow on the incoming side of the restrictor plate is still less restrictive (because it is still attached to the 4″ hose of my setup vs. a 2 5/8″ hose and the stock snorkel ) the airflow numbers recorded are probably higher then if the airbox was fully a stock setup. Still, the test will give a fairly accurate result of the real world results of opening up that stock 1 3/4″ inlet to 4″s.

Looking at the graph (click on the picture to the right for a larger view), at low RPMs the Fogged’ box seams to flow a bit better than stock. In the midrange the flow is basically stock, then at 4000 rpm or so the difference begins to grow and above 4800 it grows very quickly. The difference is about an 8.5% increase of air flow at 6400 RPM. That means your engine is burning about 8.5% more fuel there too… which also means you are producing about 8.5% more power! In fact because you are getting more air in the cylinders at higher RPM (increased volumetric efficiency) you will have a higher effective compression ratio and you will extract slightly more power from the air and fuel you were already burning before the mod in addition to the extra power for the extra air and fuel.

Now my thoughts as to why the ‘Fogged’ midrange flow is nearly stock. Simply because in that range the stock airbox is not the limiting factor. I assume if there is a problem (the cylinders could be filling to capacity) that it is the intake manifold in that range. Above 4800 rpm the DISA setup has changed over the butterfly in the manifold and the stock airbox was limiting flow again.

As an aside I also tested the intake air temperature. According to my center console computer it was 70 degrees during the test. The intake air temp. (as read from the DME using OBDTOOL) was 75 degrees while just cruising around and when I floored it for a few seconds it dropped to 73 degrees and stayed there.

I’ve tested a similar mod on a 318ti and recorded about a 5% airflow increase. That car was a ’97 with the additional throttle body in the airflow (read extra restriction) and it the rest of the engine was totally stock.

I’ve also done before/after 0-60mph runs using a G-Tech Pro. With just the Remus exhaust I was able to get a best time of 8.1 seconds. After the airbox, throttle body and Garrett Lim’s software (with stock 6500 rpm rev-limiter) my best times dropped to 7.45 seconds. My software was overwritten last December, by the way. Since then I have run stock software with the box.

Tools you need to build it:

Something to cut a hole in the plastic airbox. You could use a 4 1/8″ hole saw, reciprocating saw, Dremel or whatever else you feel comfortable with.

A Dremel with a heavy duty cutting wheel, a grinding stone and if you are using it to make the main hole the dime sized metal bladed circular saw and one of the grinding stones.

Eye protection (you are going to need it!)

10 mm socket and socket wrench

Hot glue gun with extra strength glue

Regular screwdriver

Permanent marker

Scissors and Wire cutters

Optional but recommended: Propane torch and plumbing solder, only needed if you are going to install the rodent screen in the inlet

Stuff to buy:

Go to the nearest Home Depot or the like and in the ventilation section get an aluminum 5″ to 4″ duct adapter. This is a tubular piece to allow a 5″ hose to plug into a 4″ hose and should cost about $3.

Optional but recommended: While at Home Depot in the ventilation department you need a ‘Rodent Blocker’ which is just a square piece of heavy mesh which is meant to go on your clothes dryers exhaust to keep mice from getting into you house. Figure a buck or two for this.

Go to a Pep Boys or whatever and in their ventilation section they should have a 4″x72″ air intake type of plastic hose for under $15. Anything similar should work OK but make sure it’s flexible. The stuff at Pep Boys worked really well and is very smooth on the inside for better air flow. Also get a 4.25″ hose clamp for a buck.

Very optional: can of flat black spray paint… high temperature outdoor gas grille paint works OK

Making the inlet:

First thing you need to do is to make the 4″ inlet out of the adapter you bought at Home Depot. To do this on the expansion funnel (between the 4″ and 5″ tubes) you need to cut/drill the two rivets. This lets you separate the adapter into 3 pieces, the 4″ tube, the expansion funnel and the 5″ tube. We only need the 4″ tube with the ‘rib’ on the side that was connected to the expansion funnel which opened up to the 5″ piece. The 4″ diameter tube will become your inlet into the airbox.

Optional but recommended: Cut down the ‘Rodent Blocker’ to a circle that will just barely fit inside the ‘rib’ on the inlet and solder it in place. This is a safety step to be sure a rodent doesn’t climb up your airhose and decide to make a nest in your airbox.

Very optional: spray paint the intlet. Paint doesn’t stick very well so it will take multiple coats. I’ve found that it helps if after each coat of paint you ‘bake’ it on with a hot air gun but even then it can come off fairly easily.

Completed inlet along with the airhose and hose clamp. This is all the parts required for the Fogged airbox.

Adapting the airbox:

It would be helpful if you have the car up on ramps or jack stands but it isn’t required. You need to get the bottom half of the airbox out of the car. To do that release the four clips holding the top of the airbox on and move the top aside. Take out the air filter and put it somewhere clean till you are done. On the fender side of the airbox there are two 10 mm nuts holding the air box in place. Remove them.

Above the radiator is the big black plastic box which holds the stock intake hose. Take the cover off of this by removing the (4) 10 mm bolts. Two are right in front of the plastic box in plain sight, the other two are right behind the plastic box. Lift the cover of that off and put it out of the way. You will now see the stock hose and where it connects to the snorkel on the airbox. Just pull that hose off and the bottom of the airbox can be removed from the car. While you are at it disconnect the other end of the stock hose and remove it from the car as it’s not needed.

Now with the bottom half of the airbox out of the car remove the external snorkel from the box. There is a clip on it that will let the snorkel slide off the box. Notice how tiny the hose is at the end of the snorkel! Next the internal funnel needs to be removed. There is a clip on the top of that and another clip on the opposite side of the box that lets you take the plastic frame out along with the sound deadening material. Don’t worry if you break some of the plastic frame pulling it out… I left mine out and it’s not a problem.

Now comes the fun part, you need to cut a 4″ hole where the stock hole is. Put the 4″ side of the inlet over the hole, on the outside of the airbox, and draw a new circle on it with the marker. Don’t center the new hole over the old one. You basically want the new hole to be as far forward on the airbox as you can make it. You need the inlet to be forward so it can clear your steering reservoir when you reinstall the box.

Now PUT ON YOUR EYE PROTECTION!!!!! – Using whatever method you decided on, cut out that 4″ circle. This is the most time consuming part of the project as hot, nearly liquid plastic is going to be flying around so be careful! Be sure to also look inside the airbox as in a couple of places there are plastic ribs and such that you need to cut from the inside for the hole to come out. After you get the hole cut out test fit the inlet into it. The inlet should fit through the hole but stop at the ‘rib’ on the inlet. For the test it is easier if you just put the 4″ side through the air box from the outside but this isn’t how it will be when you are done. If you can’t get it to fit use the grinding wheel to smooth and enlarge the hole. It should be as tight a fit as you can make it without distorting the inlet. After you have the inlet fitting in the hole remove the inlet from the airbox. Scrub out the inside of the air box with a brillo pad or something similar to remove all the plastic bits that got thrown around when you cut the hole. After you get it all cleaned out dry it.

Now put the inlet into the airbox for real. The side with the rib goes inside of the box with the 4″ tube pointing out the hole. Only have the tube protrude from the box up to the rib on the tube hitting the inside of the airbox. The rib will keep the inlet from pulling through the box if you cut the hole properly. Now from the outside of the box seal the inlet to the box with the hot glue.

A slight air leak here isn’t critical, as it’s still before the air filter, but do the best you can. Do NOT use a silicone glue as it could cause problems with your O2 sensors.

After the glue has set, slide the 4″ air intake hose over the inlet protruding from the airbox. It is a very tight fit but if you take your time and work it around the inlet you will get it on. Secure it in place with the hose clamp. Do not overtighten the hose clamp as you could deform the inlet. You could cut the length down to about 3-4 feet now or you can wait till it’s installed then cut it.

Now reinstall the airbox into the car. The tube and hose should just fit into the car but it will fit if you cut the hole in the proper position. You can either put the old air intake cover back over top of the radiator and put back in the (4) 10 mm bolts or pull the bottom half of the plastic assembly off of the fan shroud and out of the car. I took it out of my car but if you want your intake to look stock leave it all in place.

Reattach the (2) 10 mm nuts holding the airbox in place. Put the air filter back into the airbox and secure the cover with the 4 clamps. Be sure you get a good seal. Now would be a good time to replace your air filter if you haven’t in 10k miles or so.

Route the hose pretty much straight down along the side of the radiator. This is easier to do from under the car but is manageable from above. Run the hose into the opening that leads into the front bumper, right in front of the wheel and place the hose opening behind the foglight. Trim the hose as needed to do this. You may want to disconnect your battery for a few minutes to reset the long term fuel trim (adaptation) that occurs in your DME but it isn’t really needed.

At this point you are done. You too now have a Fogged Airbox. Go take your car for a spin and run it up to redline a few times! You are going to love it!

Fogged Airbox FAQ:

(Q) Why not put the hose in front of the radiator or below the car or add a scoop or where ever?

(A) I’ve tried a scoop and it resulted in no measured airflow increase. It also greatly increases your chances of hydro-lock. Putting the hose behind the fog light gives good airflow and you would need to drive through a VERY deep puddle (several feet) before you would have a problem. Hydro-lock occurs when you fill your combustion chamber with enough water to stop the piston on its compression stroke. When this occurs you cause major damage to your engine. Even if you submerged your hose in water I don’t think the M44 creates enough vacuum to suck water up the 4″ diameter hose, then fill the airbox and finally draw it into the combustion chamber. If it was 1″ diameter hose, yes but not the 4″ hose. Your airbox has a drainage hole in it that would act as a vacuum relief if the main hose was submerged. Having said that it doesn’t mean I recommend that you drive through very deep puddles. You are not a U-Boat captain after all. You also want to limit the number of bends the hose needs to make as each bend will cause some restriction. Keep it simple and put the hose behind the foglight, it works.

(Q) Won’t rain get behind the fog light and get into the intake?

(A) Yes, but small amounts of water isn’t a problem. This can happen on the stock setup during driving in the rain or on very foggy nights. It basically wets your filter and since it is still a paper filter there is no problem.

(Q) Won’t I get check engine lights? IE… Dinan says that if the mod worked it would cause Check Engine lights as the DME won’t know how to deal with the airflow. They also claim the engine will run lean with any air intake on it and no ‘Stage II’ software in the car.

(A) Simple answer: No

Much longer answer: I’ve put around 15k miles on my car and never had a Check Engine light. No other Z3 owner that has done the mod has had lights that were caused by the Fogged airbox either. Remember how your fuel injection works, the HFM directly measures the airflow into your engine and injects the appropriate amount of fuel. It ‘knows’ how to deal with the increased airflow. This is assuming proper air mass metering by the HFM. I have done wide open throttle (WOT) runs recording my O2 sensor data vs. RPM to see what mixture I’m running at. At WOT my engines goes rich (O2 data at 0.8v) from right off idle and stays very consistent (+/- 0.05v) all the way to the rev-limiter. IOW, with the Fogged airbox the HFM is properly metering the airflow increase and the DME is adding fuel as needed throughout the rev range. This is with stock BMW software in my DME. If this was not the case the O2 voltage would drop off (go leaner) as I got above 4k RPM where the airflow increase occurs. On other types of fuel injection: air-flow metering or speed/density the DME would NOT be able to measure the additional air and they would need a ‘chip’ or ‘software’ to properly deal with the increase flow. On our cars this is NOT the case.

Even IF what Dinan claims was true (in that it applies to ALL intakes, it is not true) why wouldn’t the ‘Stage I’ software (which makes your engine run slightly richer at WOT and slight advances your timing) be enough? A theory on that: Assume for a second you have two intakes.. their actual airflow into the engine is the same. But one intake has smooth laminar flow at the HFM and the other intake has turbulence at the HFM. What would happen when you put them on your engine? Again, if you look at the inside of your HFM you will see that it actually only samples a small fraction of the air that passes through it. Based on that small sample it calculates the total air mass. This works fine if the airflow through the HFM is nice and smooth. In the case of the intake with smooth airflow through the HFM if you increase the airflow through the HFM your DME will properly measure the airflow increase and add fuel as required. In it’s maps it says for ‘A’ amount of air inject ‘X’ amount of fuel. Because the metering is accurate you are running at the proper air to fuel ratio.

Now what happens if you put on the intake that flows the same amount of air but causes turbulence at the HFM? Because the HFM only samples a small part of the airflow if the airflow through the HFM is turbulent the HFM will NOT properly meter the mass of air flowing through it and the DME will inject fuel based on the INCORRECT metering. You could end up running richer or leaner depending upon which direction the metering was off. The DME reads that you are taking in ‘B’ amount of air so it injects ‘Y’ amount of fuel. Since you are actually injesting ‘A’ amount of air (it was just mis-metered by your HFM because of turbulence) you should be injecting ‘X’ amount of fuel. But because it is in fact injecting ‘Y’ amount of fuel you are NOT running at the proper air to fuel ratio.

So, what can you do about this? Either smooth out your airflow for proper metering OR add a ‘correction’ (re-calibration) into the DMEs maps so that when it meters ‘B’ amount of air (still actually flowing ‘A’ amount) it in fact injects ‘X’ amount of fuel. This would result in you running at the proper air to fuel ratio.

If you ran that ‘correction’ on a car that meters its air properly (say a stock airbox, or an intake with smooth airflow that metered properly) you would end up running at the wrong air to fuel ratio. Hence, ‘Stage I’ and ‘Stage II’

(Q) What is laminar airflow and why is that important to your HFM?

(A) This is an attempt to explain it, not the best example but it was all I could think of. Picture six lines of people all running parallel to each other waiting to get on a subway.

Subway

A B C D E F

A B C D E F

A B C D E F

A B C D E F

A B C D E F

A B C D E F

A B C D E F

A B C D E F

RULE: When lines C and D move forward 1 person lines B and E move forward 1/2 a person and lines A and F move forward 1/4 of a person. Knowing this and starting at the front of the lines by watching the people in any single row (A,B,C,D,E or F) you can determine how many people total have gotten on the subway. For example if the first person from row A just got on the subway you can calculate that a total of 14 people have boarded the train. You use a small sample to determine the total knowing the ‘flow’ characteristics. This is what your HFM does but for air mass flowing into your engine.

(Q) Will I really feel the difference? Can it really work that well for so little money?

(A) Yes!!!

I have a very hard time convincing people that this works as well as it does. I’ve never heard from a person that has done it and not been thrilled at the difference. Above 5000 rpm it feels like a totally different engine. Now your engine pulls HARD all the way to redline. You might even hit the rev limiter a few times while you get accustomed to the difference.

(Q) Do you really think BMW screwed up on the airbox design that much?

(A) I think they met their design goal, so in that sense they didn’t screw up at all. Their engineers had to make a compromise between noise and airflow. The stock airbox acts like a ‘muffler’ for intake noise. Just like any other muffler this limits airflow somewhat in the pursuit of reduced noise. The Fogged mod is sort of like putting on a straight pipe for your intake. It lets air in easier but it also lets intake noise out easier. Under acceleration you will get a little bit of an intake roar but it sounds great and is perfectly appropriate in a sports car.

(Q) What do you get out of all of this?

(A) Besides the satisfaction of helping out other M44 Z3ers, nothing. 😉 To that end if you do Fogg your airbox please e-mail me or preferably post a message on the Z3 message board with your opinions on it.

(Q) But xxxx tried a K&N and noticed a huge difference in performance, why?

(A) Most of the people I’ve talked to that tried a K&N decided to give it a try when it was time to replace their paper filter. The reason they felt the increase in performance wasn’t from the K&N itself but because their paper filter was clogged and needed to be replaced. If they had just put in a new paper filter they would have felt the same thing. I replace my filters every 8-10k miles, I can tell when they need to be replaced as my gas mileage starts to drop.

Photographs courtesy of Rich Carlson, Robert Leidy and Tom Mosteller, thanks guys!

The Fogged airbox is copywritted by Shawn Fogg and is for individual use only.

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