Author Topic: MAF Conversion: It's Happening, Who Is Interested? (Read 39227 times)

bmwman91 · « **on:** May 03, 2012, 01:33:13 AM »

Many of you here were following my MAF conversion development thread last year. I lost a lot of my steam 8 months ago due to getting engaged and a job change, but I finally got around to dumping some cash into a first run of these. As some of you are aware, I had a timing chain failure and I am opting for a Metric Mechanic motor as the replacement. This got me thinking about the MAF conversion, and at the very least I wanted one for my new motor. Since the cost of producing one unit is silly, I figured I'd buy parts for 10 of them.

I probably won't have all of the parts for a good 2 weeks, and it'll take me another week after that to assemble & test a couple of them. My new motor isn't going to be ready until maybe July 2, so I can't do much with my car until then. Still, I have run earlier versions in the past and I know how to bench-test them to prove them out. Even still, I would like to see how things work out on a couple of other people's M42 cars. If you want to do a little beta-testing and live in the SF Bay Area (I'd consider folks further away if they are comfortable with electrical work and their M42 isn't their daily driver) let me know. I would probably need 2 - 3 people to help out, and you'd get a discount for it.

I made some improvements to the design (immersion-gold finished PCBs, industrial/MIL spec components, additional parts so users don't need open barrel crimpers) so the cost is probably going to push $250 as opposed to the initial $200 I had wanted to go for. While I don't want to charge more for it, those improvements in quality & ease of installation seem justifiable. The price is for the converter hardware; the MAF sensor is still up to the user to buy, and you can get them for $75-$150 new. Users can easily use open element air filters, or modify their air box a bit to use it with that.

Anyway, what sort of interest is there in this? All units will be hand built be yours truly (uugh!) since the cost of contract assembly isn't really sensible for quantities of less than 100. If these do well, I can invest the proceeds into a larger production run.

Thanks guys!

colin86325 · « **Reply #1 on:** May 03, 2012, 07:31:14 AM »

I think I would be interested.

So you were able to properly tune out the resonance peaks that you were seeing? (I can't recall what the exact difficulty was.)

wazzu70 · « **Reply #2 on:** May 03, 2012, 12:19:19 PM »

Im running speed/density now so I dont need a MAF. I just want to say that a MAF can really help out the engines response. Hopefully people are interested in these. Have you posted the same offer on 318ti.org? Might be some intetested people there as well.

Also, have you looked into Millers MAF conversions? Not sure if they make one for an M42 though. Maybe you could use some of the components to cut costs like the MAF housing.

DD318is · « **Reply #3 on:** May 03, 2012, 01:25:22 PM »

Hi,

Where in the Bay Area are you located?

What are the advantages of this conversion?

Thanks,

Dave
91 318is
in Santa Cruz

bmwman91 · « **Reply #4 on:** May 03, 2012, 01:35:17 PM »

Quote from: colin86325;112304

I think I would be interested.

So you were able to properly tune out the resonance peaks that you were seeing? (I can't recall what the exact difficulty was.)

Yup, no resonance issues at all. That's what 90% of the firmware is dedicated to!

Quote from: wazzu70;112312

Im running speed/density now so I dont need a MAF. I just want to say that a MAF can really help out the engines response. Hopefully people are interested in these. Have you posted the same offer on 318ti.org? Might be some intetested people there as well.

Also, have you looked into Millers MAF conversions? Not sure if they make one for an M42 though. Maybe you could use some of the components to cut costs like the MAF housing.

For now I am trying to keep this slightly contained since I am doing a small production run. Once everything looks good, I'll have a contract manufacturer make a bunch for me.

I am not 100% sure how Miller's conversion works. I think that they gave up on the M42 conversion too, probably because of the resonance issues. How theirs works is also slightly unknown...I do not know if they are just remapping the ECU and plugging in a dummy resistor in place of the temp sensor, or if they modified the firmware to actually use the mass flow rate. Either way, their setup requires a chip and mine doesn't.

Quote from: DD318is;112313

Hi,

Where in the Bay Area are you located?

What are the advantages of this conversion?

Thanks,

Dave
91 318is
in Santa Cruz

I am in Mountain View.

The biggest advantage on a stock motor is an improvement in throttle response. The MAF is far more sensitive than the stock VAM. The stock VAM is pretty well sized, so not much power is to be gained on a stock M42, but a bored/stroked one with some head work would breathe easier with a MAF.

The other big advantage is reliability. Our VAMs are getting old, and a lot of folks are having issues with the carbon track wearing out & giving intermittent fuel cut, and lousy calibration which causes rich/lean running. This setup has no moving parts, can be cleaned with alcohol, costs about the same as a rebuilt M42 VAM and the MAF itself is cheap & readily available new.

monty23psk · « **Reply #5 on:** May 03, 2012, 08:43:58 PM »

I really want one but no funds in the bank for this. I will start selling some parts to see if I can get the funds by the end of this month.

bmwman91 · « **Reply #6 on:** May 04, 2012, 12:59:52 AM »

Don't worry about hurrying. I won't have all the parts & materials for a couple of weeks, and it'll be a few more until I have them assembled, tested & out to a few beta-testers.

monty23psk · « **Reply #7 on:** May 04, 2012, 10:00:27 AM »

Great. I rather get your device than have my maf rebuild for $100. Right now I have a rough idle and 99.9% sure I have no vac leaks but get a maf code on the stomp test. So I either have bad maf, ICV is bad or rubber intake boot might have a leak. All hose have been replaced with silicone ones. Maybe FPR. I believe ICV is fine as it adjusts correctly with AC is on. A few times the idle hunts but mostly is just rough and in the morning it runs rich as I smell burnt gas. Just havent had time, time, as I have 1 year old and new house taking my time, not new job and wedding, did that 3 years ago so I know the feeling. lol

DesktopDave · « **Reply #8 on:** May 04, 2012, 11:19:06 AM »

I love this sort of thing...one more problem with these great cars getting resolved! Why isn't this a sticky?

I'm in...

zacrl1230 · « **Reply #9 on:** May 04, 2012, 03:27:18 PM »

I like!!

Sidenote----- Hey dave saw a glass moon roof on e-bay for like a grand, I think it was you that put that on your want list in some other thread

DesktopDave · « **Reply #10 on:** May 04, 2012, 05:26:18 PM »

Quote from: zacrl1230;112333

I like!!

Sidenote----- Hey dave saw a glass moon roof on e-bay for like a grand, I think it was you that put that on your want list in some other thread

LOL, that'd be ideal! A roof worth more than my car! IIRC that roof has been on there for a while. At that price it'll likely stay right where it is...

bmwman91 · « **Reply #11 on:** May 16, 2012, 02:08:32 AM »

Alrighty, the first PCB is going together pretty well so far. I had to reorder a couple of parts because I mixed up the packages (ordered SSOPs when I needed SOICs) and they should arrive Friday or Monday. From there, I have to keep my fingers crossed that I laid out the PCB properly and put the right resistors/capacitors in the right place lol. This is the only one I am hand-soldering...40+ 0402 components & a bunch of small pitch ICs...my eyes are sore. I think I'll use solder paste & a toaster oven for the rest lol.

DesktopDave · « **Reply #12 on:** May 16, 2012, 07:58:53 AM »

Progress is good!

What off-the-shelf MAF will you be using? I'd suggest a Ford V8 unit to match my injectors, but that might be too big. I'm planning on a Ford O2 sensor to complete the set.

bmwman91 · « **Reply #13 on:** May 16, 2012, 11:28:52 AM »

I am working with a Bosch / VW HFM5 unit. It flows up to 800kg/hr, which equates to 400 CFM at 25�C, and 311 CFM at -40�C which is the worst-case condition in terms of flow capacity. Since I doubt that anyone is out flogging their car at 40 below lol, the reduced volumetric capacity in cold conditions is a non-issue. Anyway, I like this sensor because it is readily available, inexpensive ($105 for a new Bosch one, less for off-brand & rebuilt) and it fits the M42 intake boot perfectly (75mm outside diameter of inlet & outlet).

I designed the system to be modular so that I could allow different MAFs to be used. The thing is that I need to get the operating curve of a MAF before it can be used with this setup, which means either trying my luck with Bosch or obtaining a new sensor & putting it on a flow bench.

DesktopDave · « **Reply #14 on:** May 16, 2012, 02:28:38 PM »

What VW did that unit get installed on? Google tells me that some 5-series have them. New is better though, no doubt. One less potential problem.

Oh - forgot to tell you that I found an e34 535i at the yard. Figured I'd measure the airbox.

It was really small - especially after something short and very solid pushed it back into the front passenger wheel well housing!

I'll keep looking.