Author Topic: M42 MAF Conversion: SUCCESS!!! (Read 44028 times)

bmwman91 · « **on:** April 21, 2006, 11:36:07 PM »

Well, after some fiddling with the system's transfer function, the car now runs like a champ. The 1st set of conversion values I used had a little discrepency (the resistor I used to mimic the ambient air temp sensor told the ECU it was 21.4C, while the air flow was converted at 11.6C...oops). It caused the car to think there was 3-4% less air going in that there actually was...and a 3% lean condition is a LOT. That would kick a target AFR of 15 to ~15.5. Oops...

Anyway, I fixed the mistake and BAM it runs great. Just by looking at the instantaneous MPG gauge I can tell all is well...behaves the same as when the AFM was in there...the Motronic thinks the AFM is in there, which was the goal.

Now, who cares about the above stuff, right? You want:

Results:
- Idles a LOT better...none of that unsteady nonsense...and the coming-off-throttle stumble is all gone.
- The car is a LOT louder at WOT, but that is because I have an open-element filter on there at the moment.
- The midrange power seems a little better, as does the high. There is a weird power-deficit at 4-5000RPM. That I attribute to the air box being gone. Removing it changes the induction track harmonics. I guess it did so in a way that between 4 & 5kRPM the pressure waves cancel a little more. I am still making an adapter to fit the air box, but I will also look into adding a Helmholtz resonator or velocity stack at the intake entrance to help this.
- Mileage should be better in one respect. When you floor it with an AFM, the door has some inertia, and flies open a little past where it should be. The Motronic sees this, and will momentarily inject too much fuel while the transient effects of the trap-door system are still significant. Once it reaches its 'steady state' its fine...but those momentary over-injections add up I would guess (well, if you like to floor it like I do, esp on the HWY). This also kills the catalyst faster, so good riddance.

I will report again after a few days. I only got about 30 minutes of test time today, but seeing how it does around town will be a good test. Thank God I'm done...my end-of-semester just got easier!

asubimmer · « **Reply #1 on:** April 21, 2006, 11:58:56 PM »

awsome!!!

jfdublyu · « **Reply #2 on:** April 22, 2006, 12:35:52 AM »

dude, that is so sweet man. get some 0-60 and 1/4mi times stat! congradulations on the success

nickmpower · « **Reply #3 on:** April 22, 2006, 01:31:50 AM »

I would get it run on a dyno to see what the air/fuel does in general and especially where the power deficet is. I doubt its because of the harmonics

bmwman91 · « **Reply #4 on:** April 22, 2006, 04:14:40 AM »

Haha Nick has discovered me...jk.

Yeah, I have to figure out what the deal with the 4kRPM is. Honestly, I think it is a change in the induction system harmonics. The deficit is there under WOT conditions. In WOT, the Motronic goes into Open-Loop mode, ignoring the AFM input. Being that the M42 is HIGHLY tuned from the factory, something like removing the air box could easily cause significant changes in the power curve IMO.

Now, perhaps I am just noticing an improvement in the rest of the power curve, with less pronounced results in the 4k-5k range. It is speculation at this point. When I have a chance/$$$ I will dyno it and see exactly what the difference is. I have an LC-1 WBO2, so I can monitor the AFR. Hopefully within the next few days I will be able to get some REAL analysis back to you all. Unfortunately I am very very busy working out my career plans. I am trying to nail down a job at either NUMMI or Cisco Systems, so that is priority #1 right now.

PS
Pleas forgive any spelling errors. I am drunk as shit right now...in celebration of my MAF success. Going to work tomorrow at 9AM is gonna suck royally!

tim_s · « **Reply #5 on:** April 22, 2006, 05:48:51 AM »

Quote from: bmwman91

Haha Nick has discovered me...jk.

Yeah, I have to figure out what the deal with the 4kRPM is. Honestly, I think it is a change in the induction system harmonics. The deficit is there under WOT conditions. In WOT, the Motronic goes into Open-Loop mode, ignoring the AFM input. Being that the M42 is HIGHLY tuned from the factory, something like removing the air box could easily cause significant changes in the power curve IMO.

Now, perhaps I am just noticing an improvement in the rest of the power curve, with less pronounced results in the 4k-5k range. It is speculation at this point. When I have a chance/$$$ I will dyno it and see exactly what the difference is. I have an LC-1 WBO2, so I can monitor the AFR. Hopefully within the next few days I will be able to get some REAL analysis back to you all. Unfortunately I am very very busy working out my career plans. I am trying to nail down a job at either NUMMI or Cisco Systems, so that is priority #1 right now.

PS
Pleas forgive any spelling errors. I am drunk as shit right now...in celebration of my MAF success. Going to work tomorrow at 9AM is gonna suck royally!

good work! you really think the m42 is highly tuned out of the factory? I'd say its pretty conservatively mapped, or at least ours in th UK are.

shellback · « **Reply #6 on:** April 22, 2006, 09:23:06 AM »

Congratulations!
And I wish you the best of luck and success with getting the new job.

Chris

dino245 · « **Reply #7 on:** April 22, 2006, 11:11:23 AM »

Now that you have succeded now time to produce them and sell them to us. I have been working with an smt6 but I would love a plug and play set up instead.

bmwman91 · « **Reply #8 on:** April 22, 2006, 12:23:28 PM »

Quote from: tim_s

good work! you really think the m42 is highly tuned out of the factory? I'd say its pretty conservatively mapped, or at least ours in th UK are.

Well, I was referring more to the construction of the engine being well-done. I agree, the original software was quite conservative.

jfdublyu · « **Reply #9 on:** April 22, 2006, 12:59:03 PM »

yeah man, here's a job idea: mass produce these bad boys! i know probably a good half of members here would buy, and who knows how many else would. just a thought.

bmwman91 · « **Reply #10 on:** April 22, 2006, 06:10:59 PM »

I am working on getting a product together that I would feel confident selling. Right now it is a working prototype, and I am designing a PCB to be made, as well as selecting the smallest possible housing and whatnot.

Here is the hard part: Fitment.
The electronics are not too big a deal, and I could have a converter made & ready to go within a month or 2. Now, if I had to make adapters & stuff so it fit reall really easy, that will be a while. Right now I have it fitting in with a $4 reducer from AutoZone and a 35 cent pipe fitting from Home Depot. That is for the MAF-to-Air Boot side anyway. Making it fit the air box is another story. I have a big open-element K&N on there right now, which works. I could also try to make a heat shield so an open element filter could be used instead, but that is still $$$ & time.

So, how do all the DIY'ers here feel about me selling them the converter box and necessary connectors that have to be spliced in, but it is up to you to get the MAF (easily sourcable at wreckers, or refurb'ed at kragen for like $60) fittings and filter (and make a heat shield yourself)? I am still looking into the air box fitting...I just need a really short silicone reducer. The only other part needed will be the circular-to-square adapter found on M10s' & M20s' AFM's.

So, what do people here want? I will do my best to figure out the adapters...my current ones WORK, but are not as nice looking as I would like.

nickmpower · « **Reply #11 on:** April 22, 2006, 06:55:05 PM »

just give me the converter ish

StreetSpec_iS · « **Reply #12 on:** April 22, 2006, 11:12:17 PM »

^ what he said.

what MAF were you using again?

sheepdog · « **Reply #13 on:** April 23, 2006, 12:02:47 AM »

Quote from: bmwman91

So, how do all the DIY'ers here feel about me selling them the converter box and necessary connectors that have to be spliced in, but it is up to you to get the MAF (easily sourcable at wreckers, or refurb'ed at kragen for like $60) fittings and filter (and make a heat shield yourself)? I am still looking into the air box fitting...I just need a really short silicone reducer. The only other part needed will be the circular-to-square adapter found on M10s' & M20s' AFM's.

So, what do people here want? I will do my best to figure out the adapters...my current ones WORK, but are not as nice looking as I would like.

I have no problem with that.

Kind of leaves it open for you to experiment with the air cleaner side, and decide what is best for you without paying for something you do not want.

The big question is what would we be looking at for your kit?

bmwman91 · « **Reply #14 on:** April 23, 2006, 12:26:14 AM »

I will try to get you all some pricing info within the week. I just finished drawing up the PCB layout. So, once I have all my costs nailed down and my partner & I talk it over we will let you know.

And it makes my life a lot easier at this point hearing that you just want the magic box. More to come.....