M42 MAF Conversion: SUCCESS!!!

[bmwman91]

Now that I have a nice new Bosch LSU4.2 wide-band sensor in there I should try out the MAF conversion to see if the problems disappeared.  The old one was shot to hell, and the car runs 10 times better now.  If all is well, then that could cut a couple weeks off of redevelopment time!

I ordered up a round of PIC MCU's and will be building a reeeally basic datalogger to take RPM, air flow and EGO readings.  So, if the thing still acts silly at WOT below 3000RPM I will have to build & program a little DAQ setup to see what is going on.  Cross your fingers I don't!

PS
Anyone wanna write some simple C or BASIC code to take some serial data in from an RS232 port?  It will be 2 8-bit numbers and a 16-bit one.  Just have to be stored in a 3-column, tab-delimited text file, and that much I can probably do myself after refreshing stuff I learned 3 years ago.

[Gizmo318i]

What converter you use for your maf conversion?

Dastek piggyback Unichip.

[Nathan]

In regards to the stutter this might help,
This was on another forum, sourced from a manual, dealing with a different bmw with a afm. They were not going to maf, just saying its the same basic setup and someone was having a stutter about like yours. And here was one of the possible causes..
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"The shut down happens if the air volume sensor registers an air volume that is higher than permitted for current RPM and load, for more than 1.5 seconds. The limit is at 15% above the volume at full throttle. When injection is turned off, the compression process collapses immediately. Injection is resumed when the air volume sensor registers a pre-determined value that is below the full throttle amount. This new value is maintained for 4 minutes as a cut-off value forthe injection unit.Engine performance is slightly reduced during this time. After 4 minutes,the original value is restored."
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So possibly, if this bmw works like the other, by 3k rpm, with the new maf, the cpu reads a higher air volume than is permitted for the RPM. This could mean your parameters are set too high in the 1k-3800k RPMs due to how much more free flowing the maf is (especially around idle), the (voltage?) reading might need to be lessened to look weaker so it doesnt trip this air/rpm ratio.

If there was a way to get the car to say 4500RPM before 1.5 second of turning the car on, in neutral, you could test this but 1.5 seconds is pretty short. If it holds the value for 4 min, probably wait 5 min before tries...

Ive been watching this thread for a while and really want to see it happen. Good luck with it, hope this helps..

[JetBlack95]

ha ha ha and the Gizmo has arrived....

[m3someday]

Hi guys,

I'm new to this club and thread.

I've been working on my own MAF conversion while keeping track of this thread. For the past 3 month, I've been trying to use a 320i and a Mercedes Pierburg MAF. (BMWMAN - FYI - the Pierburg MAF used in the Mercedes Vito diesel van is only about $50 brand new!).

I've blown the 320 MAF (i think!) while testing cause i can't get any voltage output from it. With the Pierburg MAF, I've hook up an APEXI SAFC II fuel converter to try convert the values to what the ECU expects. I know I need to dyno tune to a wide band O2 sensor to get it right.  But i haven't even reach that stage!

Idle is horribly unstable. It goes cyclicly up to about 1500+ and down 200+ and then finally dies. When i correct the mixture up to 50% less fuel (i understand that the voltage output from the MAF is much higher than the AFM) i get pretty stable idle but the engine seems to cut when i gaz it.

I'm close to giving up so unless someone has an idea, i've got my paypal ready for BMWman's product!

BMWMAn - I would probably need you to ship the MAF together with your converter. I'm from Singapore and there aint no Mustangs or tauruses here!....or maybe you can callibrate one for the Europe/Asia market using the Pierburg MAF. The Vito van is real popular here and Europe and the MAF is dirt cheap!

[Vladi]

Would a VW Golf 4 1.9TDI MAF work? I've got one lying around catching dust all day.

[bmwman91]

I have actually switched to a VW MAF for the newer version.  It fits a lot better and is cheap.  Still debugging the weird behavior, but it is looking more and more like it is related to being atached to the air box.  It migth not be possible to work with it, at least with this sensor.

[m3someday]

Actually, the VW MAF (by Bosch) and the Mercedes MAF(by Pierburg) is similar and interchangeable. The housing may be different but the MAF inserts are the same. My Pierburg MAF was actually "borrowed" from my VW Transporter TDi (Eurovan in US i think).

It was supposed to be running the Bosch MAF but the Pierburg replacement was supposed to be better and cheaper. Not sure if these new generation of hot film MAFs with digital output (i think) are the source of our unstable idle.

I don't think the VW 1.9TDi MAFs will be too different from it.

Anyway, Bmwman....when can we expect your first production models?

[bmwman91]

Haha, I wish I could say.  I have been saying "a couple months" for the past 6.  I am just having a bear of a time finding the free time and resources whilst still trying to maintain a relatively normal social life, a GF and work.  Aaah, life.

The funny thing is, I will probably have a datalogger coming out of this as well as I have had to make one to diagnose some issues.  It is a little 3-parameter one I am working on, but it can very easily become 10+ after the MAF is done.  Friggin sub-projects to the main one........

[AL GReeNeRy]

bmwman you always got the best projects.  i bet this conversion, when finished along with the COP conversion would make for great throttle response and all out engine efficiency.

[m3someday]

Hi all,

Proud to announce that with BMWman's tips, i've finally managed to make my conversion work!!!

I think the root of the problem was the Pierburg MAF. Since i blown the 320 MAF, i was hesistant of buying another one and therefore was trying to use my VW Eurovan MAF. I think the signals from this diesel MAF is just too different from what the ECU expects.

Since BMWman's product is not near production, i thought what-the-hell lets just grab another MAF and start tinkering again. I sourced for a 325i MAF, short the temp-sensor (on the AFM harness) with a 1.5kohm resistor to ground and spend a couple of hours tuning the APEXI SAFC2 to send the right signals to the ECU.

Finally managed to get stable idle and the engine revvs smoothly to 3500rpm. I'm not revving beyond that till i do a full dyno tuning with a wideband. I've been driving the car around for a few days already and everything seems to work fine. My butt dyno already says it's quicker and built up revvs quickly! I've ordered a chip from a German tuning company and when that arrives in a couple of days, i'll do the dyno.

Strangely, my wierd problem of bogging after a warm start dissapeared together with the AFM! I wrote on another post that my car is fine starting from cold but when i restart it when warm, it will idle erratically and stumble for the first 1 or 2 minutes. It works beautifully after this 1-2mins but the whole problem will start again if i switch off and restart!

Now - i don't have this problem anymore!....anybody have a clue what may have been the problem?!

Many thanxs to BMWman's for the tips!.....FYI - i've left the GREY/BLACK wire on the AFM harness disconnected. Seems to work pretty well without that mysterios wire - whatever its for!

PS - Does anybody know what the GREY/BLACK wire in the AFM harness is for and if its ok to leave it disconnected?

[bmwman91]

I BELIEVE that wire is the LLCO adjustment, and was only used on non-catalyst/non-EGO sensor cars.  And congrats on getting it to work with the Apexi unit, good luck at the dyno.  I am interested to see what numbers you put down.

Once my e-bay oscilloscope arrives thsi week, I think I can FINALLY finish up the new converter and wash my hands of the development stage for this!  I am sooo tired of having this looming over my head...and I need tires, brakes, a couple pints of OEM paint for some refinishing and to make my 6-month insurance payment...I need to sell a few of these lol!

[nobrakese36]

ready to buy let us know!!

[nickmpower]

werd. If i coud get one of these and a COP bracket in the first couple weeks of december that would be awsome

[m3someday]

Actually,

My car do have an O2 sensor and there is a dummy cat converter as well (came with the car when i bought it)

What does a "LLCO" sensor do? Is it ok to leave it disconnected? My car has been running fine without. I'll probably drop by a specialist for a diagnostic sometime next week.

But....i'm really not sure what's supposed to be in my car anymore cause it was originally an M40 engined E36 that has been transplanted with a 1995 m42 engine!

i'll keep u guys posted on the dyno results.