MAF Converter V3 Update!

[AL GReeNeRy]

Sorry for all the troubles youre goin through bmwman, but all i gotta say is YESSSS more hope for a cone filter setup!!!

[rallycarcamshaft]

FAO  Bimmaman, the web site for the piggy back unit is http://www.perfectpower.com don't know if you can get the neccessary info from that, the following text is from the tuning maual which may help you.

"The Analog map is responsible for changes made to the analog signal. The main 8 x 16 map modifies the analog signal according to RPM and analog deflection values. these changes are then multiplied by the values in the       1 x 16 row map, which is mapped according to the engine temp sensor. The values in the analog map range from -127 to 127, each value of 1, changes the analog out signal by 0.039v."

The load sensor uses one of two signals. It can either be an analog signal similar to the TPS signal or it can be a frequency-based signal. The frequency-based signal is similar to the unipolar signal.

Daft question but what does "IIRC" mean.

I have an Boshe MAF meter off a BMW E36 325i do you think this one work or not, and were do I connot the resistor to.

regards

jon finch (e-mail  -  jfinch@jfinch89.fsnet.co.uk)

[Vladi]

Hmm....wouldn't the conversion be easier if you used an M44 AFM?:rolleyes:

[bmwman91]

Just about any MAF unit should work.  I happened to get my hands on a VR6 MAF in a parts trade, and from looking around it seems cheap and readily available.

If someone can find me a good source for M50/M44 MAFs then I can make maps for those as well.  It would be nice to test a number of sensors so people can have options depending on what is avilable to them.  So...who wants to let me borrow an M44 MAF lol?

[bmwman91]

Alrighty, got rid of the funny idle.  It was due to some issues with the power supply to the WBO2 sensor.  Now that the thing actualyl stays on, the car idles fine, and no CEL or anything anymore.  One down, oen to go!  The mini-logger is ALMOST done, so I can see if this is an input-resonance issue this week and start looking into solutions.  Again, this is testing with the OEM air box.  After I get that working well, I will move on to testing with a cone filter and whatnot.

[nickmpower]

so its still cutting out when u floor it at low rpm's?

[bmwman91]

Not cutting out, but bogging badly.  From looking at the MPG gauge, I want to say that it is leaning out a lot in there at WOT.  Hopefully tomorrow night I will get some logging done of AFR's and the converter output.  I still suspect some sort of harmonic resonance, but I will also try concocting some non-restrctive vanes for the input tube to help with any turbulence generated by the abrupt square-to-round transition from the air box.

[bmwman91]

WARNING: LONG
Progress report time again.  I got the mini-logger working well enough and did some runs tonight.  The results were interesting, and to my surprise...the problem seems to be exactly what I had guessed!  Intake resonance.

The plot colors are as follows:
Green - AFR (Right Axis)
Orange - MAF Converter Output (Left Axis)
Magenta - MAF Output (Left Axis)
Blue - TPS % (Left Axis)

This was a first gear WOT run up to ~7000RPM.   You can see the big fat "blurry" magenta area...that is the problem area.  Resonance is a problem with a sensor as sensitive as the MAF unit.  The orange is my converter's output.  Prior to adding some filtering, it would have been all over the board like the MAF signal.  Based upon the AFR readings, things are running pretty lean.
http://www.e30tuner.com/projects/images/mafcon/log01.png

Here we are zoomed in on the "fuzzball."  You can see as the throttle is opened wider (blue), the intake pulses play more and more of an effect.  Above 60% open, the pulses start to get really hairy...but the important line is the orange one since that is what the ECU reads.  It is not fluctuating wildly, but is certainly taking a "low" average of the MAF signal, and hence the car runs lean.
http://www.e30tuner.com/projects/images/mafcon/log02.png

This was a 5th gear run from ~2400RPM - ~3600RPM.  Since a lot more time was spent in the trouble zone, the effect is more apparent.  See the HUGE dip in the orange curve there...this is what I need to fix.  Unfortunately, it is not as simple as tweaking some part of a conversion map since those flow rates will be seen at other times when there is not resonance creating false readings.
http://www.e30tuner.com/projects/images/mafcon/log03.png

Here we are zoomed in on the above chart.  Look between .2 and .3 seconds.  As the throttle position rises, the amplitude of the MAF output oscillations seems to increase proportionally.  There's the proof...WOT conditions at a particular engine speed are the culprit.  Basically, it seems that above 70% throttle opening, it is as bad as it can get.  The orange line DEFINITELY should not go DOWN as RPM increases!
http://www.e30tuner.com/projects/images/mafcon/log04.png

Here is a snippet from a dyno plot from my first car.  There is a noticeable "flat spot" between 2600-3000RPM in the torque curve.  This must be some point where the induction harmonics are phased in such a way that they are detrimental to the engine's efficiency.  This was a built-in problem...the MAF exacerbates it due to its sensitivity.  The VAM did not "care" much since the waves would not push the door around much.
http://www.e30tuner.com/projects/images/mafcon/dyno01.png

[nickmpower]

damn it gets insanely lean at some points, do you think that it does that stock?

do you have a plan of how you are going to fix this whole problem?

[bmwman91]

IIRC The AFR's went lean to ~16.5:1 when I dynoed the first car using the AFM and a Conforti Chip.  The M42 does run lean (ask Stu McHenery) normally...but this is excessive.

I have some ideas in the works for remedies.  I would prefer to do it all with electronics, buuut I MIGHT have to look into physical solutions as well (as in modifying the intake system to dampen this a little).

Hopefully tomorrow I will have a chance to yank the air box, make a simple 6-8" velocity stack for this and strap the rice filter on.  Maybe that will shift this harmonic nodal point that could be sitting right in the MAF or something.  I WILL solve this...but do not count on a MAF converter sitting under the Christmas tree!

[bmwman91]

I looked for M44 pictures to see exactly how they are set up with the MAF and did not find much.  Any M44 folks on here want to shoot some photos of the MAF/Airbox/Intake boot assembly, and maybe pull the MAF and get some shots of the inside?

I DID find something interesting on RealOEM.  Check out Item 4 with the red dot.

Any of the couple M44 guys in here wanna pull it off, tape over the hole and go for a little test drive?  Once it warms up, take it out and basically floor it from 2000RPM up to wherever you feel comfortable.  Let me know if you notice any "boggy" areas in the power curve without the resonator!

This gives me some idea now of what I might need to do.  I will get on BFc's E36 area and ask around on this too.

[m3someday]

Hi Guys...and BMWMan.

Its been a while since i lasted posted....been busy, but i feel a need to share my experiences with whoever's keen on doing this conversion thingy.

My MAF conversion has been working fine for the past month. Attached is the pics of the MAF set up for my E36 M42.

I used a siemens 325 (i think) MAF together with a SIMOTA CAI.

I used an APEXI SAFC2 to "condition" the signals from the MAF to what the ECU expects.

So far so good, The set-up is pretty stable all the way to redline. There is a perceptible bogging if i floor the accelerator below 2000rpm. Its not there if i gradually step on the gas or if i floor after 2000rpm. Its not irritating enough at the moment but i think i would have to address this issue in the future.

I dyno-tuned the SAFC2 with a wideband, but figures are rather dissapointing. I'm only getting about 120hp and 140Nm at the crank. Could it be an 11 yr old engine feeling its age? Other than intake and exhaust mods, my engine is stock.

What figures are u guys getting from your M42?

BMWman - many thanks for your advice, just one suggestion, could it be that the source of your stability issue is the MAF unit? I was trying to use the MAF from my VW Eurovan before but couldn't get a stable idle at all. This particular VW MAF has a 12v, 5v, gnd and signal whereas the MAF i'm using now only needs 12v,gnd and signal.

[bmwman91]

Yes, I am using the Bosch/VW MAF from a MK4 Jetta.  When I was using a Ford MAF previously, I did not have this issue.  The Bosch MAF design is very very prone to intake backflow, which is the problem right now.

How is the Siemens MAF set up...as in where is the wire/film element located?  The VW one has it sitting right in the middle of the crossection.  The Ford one had it out of the direct path in its own little alcove, which seems to be a better design by nature.

Also, how much can you get this MAF for ($), and how easy are they to get?  Do you have a source of OEM connectors and pins for this?  That was my turnoff to the Ford one...no source of OEM connectors.

Anyway, could you yank the MAF off and take some pics of it, inside and out?  You would be helping me out more than you know!  Thanks!

[m3someday]

no worries mate,

Out of town til Friday, will do so when i'm back!

cheers

[Damoj]

What did the ford MAF connector look like?  I might be able to dig something up.