MAF Conversion: It's Happening, Who Is Interested?

[bmwman91]

Do you think that some of the noise/resonance in the intake was caused by the twin-plate throttle body vs a regular throttle body?

No, that isn't really the issue. Every intake has resonant modes. It's just a hell of a lot more pronounced on a 4 cylinder since there is basically no intake overlap, so you end up with big discrete pulses. If you look at many 4 cylinder cars with MAFs, you will see resonator chambers (Helmholtz resonators) on the intake which are there to help damp out the resonances. The rest can be dealt with by the ECU. The Megasquirt guys had a heck of a time getting a MAF to work properly with 4 cylinder engines, and they finally worked it out, but they have access to information like crank position, so they can basically average the air flow value over one intake cycle. Anyway, that's not really an option with this converter since the goal is to not have to hack up any more wires than necessary.

[bmwman91]

Hi my name is Mark and I live in Reno... I am really interested in your project trials...That is if I am not too far from you. I have a 1979 320i with a e36 m42 swap.  I am really sick of chasing the gremlins in this afm setup. Poor idle, poor throttle response, etc... PLEASE let me know how it all works out and if I can get my greasy paws on a setup!!! Thanks again.... 

Hi Mark,
A well maintained M42 will idle just fine with the stock AFM, and the throttle response shouldn't be too terrible. It sounds like you may have some vacuum leaks or other old sensors causing you trouble.

[nickmpower]

Is this going to happen? I am interested in it for my DASC m42

Also I have a lightweight (8.5lb) flywheel and sometimes the cars stalls when the revs are coming down, would this help with that at all? Really only happens like once a month so I guess its not a big deal

[bmwman91]

Hey Nick,
It'll happen someday. Got a lot going on and I am not working on it actively at the moment.

I doubt that a MAF would help with your stall issue. It sounds more like a gunked up ICV. You have probably shot carb cleaner through, but I recommend submerging it in rubbing alcohol. I did that for a few hours and then shoot it up good with my fingers plugging the inlet/outlet. After a few rinses through with more alcohol I stuck it in an oven at 150 degrees for a few hours to evaporate the remaining alcohol inside. That helped my idle tremendously, and my flywheel isn't much heavier (11.5lbs).

[nickmpower]

Did you submerge the whole ICV or just the end?

I think the biggest reason I am interested in this is that it will let me run a bigger air filter, the biggest one I can fit now must has less area than the stock filter.

[bmwman91]

Yeah, dunked the whole ICV. Sloshed it around to get the air pockets out and let it sit for a while. Capped the tubes with my fingers and shook vigorously. Drained it out. Repeated that a few times. Everything was good thereafter.

What sort of intake setup do you have right now? The stock M42 AFM is good for around 180bhp before it hinders things, and even at 205bhp it might only rob like 2-3hp (and it doesn't hit max output so it's still accurate). Based on my experience adapting the M30 air filter box to my car, it is doable with the stock AFM too. You just have to cut a little more off the top.

[nickmpower]

Lol this is my intake. the afm is so long there just isnt room for a big filter. I have a tiny cone filter on there and its wedged up against the fender. Also FYI I am located in the bay area!

[bmwman91]

Damn, call me jealous...the DASC is a very rare bird! I'd definitely love to take a look at that setup sometime!