M42club.com - Home of the BMW E30/E36 318i/iS
DISCUSSION => Electrical => Topic started by: bmwman91 on November 30, 2006, 12:20:34 AM
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Alrighty, I managed to get the car to run well enough for testing finally...there are gremlins in my fuel injection system.
So, it worked. The old problem of engine-cut if floored between 2400RPM and 3000RPM is gone....but replaced lol. Now if you floor it between 1250 and 1750RPM it will die out. I will sick the O-Scope on the output tomorrow and see if it is some weird resonance thing. I AM running a big-ass ricer filter just for testing right now rather than the air box, so maybe that changed the fundamental resonant frequency in the intake that I suspect is causing this. I will test with the air box again and see if the dead spot moves again. A big huge velocity stack might be needed, but cross your fingers I just need to remap the converter a little. The idle was fluctuating oddly as well, like consistently between 600 & 900RPM. Perhaps I need to do some work on the low-flow portion of the map.
Results:
- The thing is LOUD with the rice filter. :(
- Throttle response is improved...whee!
- Not going to try to comment about power yet, I am running on little sleep and am still pissed that the car was barely running at all yesterday...and no obvious problems were found after an intake manifold tear-down.
- In the 15 minutes I drove it, it did not misfire once, so maybe the problem (see above) was a dead AFM.
Once I get this thing flawless, no dead spots regardless of where you floor it, I will book some dyno time to get AFM and MAF runs in. I am just glad this damn thing works! Therafter, the PCB order goes out and I make the first sellable test-units!
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im glad to see progress is bein made. got a question tho. are you running the maf setup wit the maf directly connected to the cone? if so, try running a little piece of tubing between the maf and the cone to help smooth out the turbulence. i noticed many turbo apps have some of tubing in these spots on their intakes..
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Yeah I was gonna make a velocity stack of sorts...but it is late and cold so I just slapped the filter on. I HOPE it will go away with the air box on it tomorrow...the problems I had before may have been from the V2 circuit going on the fritz!
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are u watching the afrs???
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I will be tonight along with the MAF output waveform. I got it all together at like 10:30 last night and just wanted to see if it would run. I am thinking I may need to remap the lowest 10% of the converter settings...the idle was a tad funny as well.
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What MAF are you using?
obv im interested in it once you get it sorted but if i need to acquire a mustang filter etc then obv im screwed cos we dont have them over here (We have to many corners for them)
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glad to hear you are running better :)
your products are awsome, keep it up!!
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I am presently using a MAF from a MK4 Jetta. It can be fitted to the air box, but I need to test that setup for bugs.
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I don't know if this will have any bearing, but I have heard that the farther away from the throttle you can get your MAF the better off you are. Something about intake tract pulses causing fluctuations in the wire temp which may be causing the "noise" you are seeing. I have a mile of intake tubing retween the maf and the throttle plate on my SAAB turbo by design.
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Yeah, I can definitely see this being a turbulence issue, possibly due to an acoustic node existing near the heated element. It has a rear cover on it, I would imagine to prevent backflow, but who it to say.
Anyway, I am going to go install it on the air box and test it out. Brb in like 30 minutes hopefully.
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OK....
Oddly, I got a Throttle Potentiometer CEL code...it would come on after idling for maybe 20 seconds.
With the air box on the MAF it still had the odd idle fluctuation, which may possibly be related to the TPS error, or mis-mapping of the converter.
The dead spot in the RPM field is now in 2 small chunks lol. There is a dead spot where, if you floor the car basically off-idle it will die, the again from like 2400 to 2600RPM. Very odd. I will see about O-Scoping the output and whatnot. I will try resetting the Motonic...I kinda adjusted the TPS contact brushes and did not reset the Motronic which supposedly self-learns the TPS positions. Grrr, what is the deal with this thing?!
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Alright, scoping it seems to have offered some clues. It is a storage scope so I could have captured the waveform, but it is chilly in the garage and just wanted to get a look with my father.
So, what I saw has made me draw the following conclusion. Basically, the MAF and converter are too damn fast and "sensitive!" They are so fast that they seem to be resolving individual intake pulses! I have no idea what speed the Motronic samples air flow voltage at, but I would guess that it is slower than the converter and might is probably taking them at pulse peaks and troughs, confusing the hell out of it. For those that know what "beats" are, the kind produced by the mixing of two or more periodic waveforms, you get the idea. This could explain the fluctuating idle...the Motronic's sampling rate at these lower engine speeds is very close to the intake pulse rate where the MAF is most prone to the induction pulses. Since it is definitely less than twice the intake pulse frequency it will have aliasing problems and resolve the wrong overall waveform (read about Nyquist frequency/sampling). Anyway I am getting waaaay off on a tangent.
Basically, this is a problem only with larger throttle openings as there is essentially very little damping of these pulses. With the throttle closed all the air is sucked through the ICV which can easily act as a damper. Even with small openings the pulses might not be getting through the cracked throttle opening without being damped out a just enough. Open them a large amount and the pulses have very little interference...and run right out to the MAF. The MAF is fast enough to resolve these.
As for the issue at the higher engine speed, this could just be due to it being a secondary or tertiary harmonic of the original problem. The cutout seems to happen around 1200RPM. The next one looks to be around 2400RPM...a factor of 2, conveniently. Why not at 3600RPM? Perhaps enough turbulence is generated in the induction system so as to damp this nonsense out.
This pressure pulse-measurement system is interesting. With the AFM, it was definitely well-damped...the flapper would not be disturbed by the individual pulses due to its relatively huge mass in comparison to the moving air's momentum, and being on a spring with friction in the moving parts. The MAF is essentially a very very underdamped system...it has no restrictions on response time other than the internal electronics and the speed of the passing air. This means I need to implement some form of damping, either in software or hardware in the converter. This means more delay (lol, like it is even noticeable by a human driver). Now, it does not matter a damn that the converter response time is presently about 970 micro-seconds...the Motronic is pobably slower since it has SO much more to do. The clock on the converter is 4x faster than the Motronic, and there is 99% less code to execute in the converter...so I think it reasonable to assume the Motronic samplng rate is a lot slower. The converter can sample at 4x the maximum intake pulse rate at 7200RPM, so aliasing anywhere in there is no problem.
I COULD look into using an RC or RLC filter to help with this, but I would prefer not to. Software is free lol, and a lot more predictable. If I were to do this in software, I would play it safe and set the averaging time to be able to deal with a 600RPM WOT condition, it would leave a 50ms delay. I do not like that, although as far as throttle response goes it would not be very noticeable...it just pisses me off that I know I could have the system run with a delay of 150 microseconds if I wanted lol.
LOL and I always hoped I could find an application for that Systems & Control class I took. I guess I did! Sorry about the world's longest post. This is how I like to stew the old brain juices...thinking "out loud." More to come. At least I now know the issue is not in the calibrations! I need to research signal filtering a little more!
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i wish i knew what you meant.. all i understood from that is that the maf can read signals faster than the motronic can decipher...
hopefully, you can make this work with a cone filter too. although some may not like it because it can be too loud and ricey and may not do anything as far as gains, i believe its a more fun experience to have.
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The noise is actually kinda fun lol. I guess the only good way to run the cone would be with a heat shield...and I am definitely not going to look into manufacturing those. Hand-building them would be a pain, and would hurt the cost considerably. Don't worry though, I will test it with the airbox and without.
Yeah I got waaaay off onto some half-baked technical tangent there. I was up late, and have been getting ~5-6 hours of sleep per night. Unfortunately, my body likes 8 hours, so this leaves me in odd mental shape.
Anyway, I love learning. I also love sharing things. I was playing around in Excel with the various waveforms, and decided to export it to a PDF with notes to help folks understand what is going on. Hopefully you will find this informative!
Adobe PDF, ~500kB
http://www.e30tuner.com/projects/aliasing.pdf
Might be typos in there. I checked, but who knows what I missed in my half-asleep stupor!
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So if the problem is that the ECU isn't sampling as fast as the MAF, could we just overclock the ECU? (mostly kidding)
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Haha. I WISH. Unfortunately, while you potentially could stick a faster crstal oscillator, you would need to do a lot of software work to get all the timing right again. Maybe if I put some Type R stickers on the unit it will work better.....
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So couldn't you just do an average of "X" number of polls from the MAF and feed that value to the DME? Maybe work in a delta factor so one value can not be more than +or- "Y" percent of the last value?
I mean you are sampleing the MAF and converting it so you can do whatever you want with it right? The thing I've figured out is the DME expects certain values from the sensors and when they don't coincide with the expected values the damn thing shuts your injectors off.
Just like you said, the AFM sends a nice linear signal but you may have that MAF signal so snesetive that the software in the DME is flipping back and forth between maps or something and just basically getting confused.
Just adding to the the discussion.
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Yes, I do suspect that at lower pulse/engine speeds the Motronic is seeing all sorts of junk values and shutting down the injectors.
Averaging this in software could be hard. I would likely need some pulse-triggered hardware, then to use some interrupt-routines to captur ethe time between peaks & whatnot. I think I have a simpler solution involving one additional componment on the input. It could attenuate the input enough to give the Motronic something workable. When I scoped this, it was prettymuch pulsing from 0V to 5V, which is the entire range of the covnerter! Anyway, this will be interesting. If this simple solution is a no-go, then software it is. Lol, anyone have a function generator I could borrow...it would help a lot!
Too bad this is not a fully sinusoidal wave situation. If it was, a simple integrator could do the trick!
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good luck!!
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Now this is someplace past the point of where my knowledge ends. For most of the racing I was involved in a Holley carburetor was sufficient as the engine was in the top 20% of the power band almost all of the time. FI was a 50 pound weight penalty and not competitive.
I have sinus trouble and sometimes it's so bad I get suicidal. Is it something like that?
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The noise is actually kinda fun lol. I guess the only good way to run the cone would be with a heat shield...and I am definitely not going to look into manufacturing those. Hand-building them would be a pain, and would hurt the cost considerably. Don't worry though, I will test it with the airbox and without.
Yeah I got waaaay off onto some half-baked technical tangent there. I was up late, and have been getting ~5-6 hours of sleep per night. Unfortunately, my body likes 8 hours, so this leaves me in odd mental shape.
Anyway, I love learning. I also love sharing things. I was playing around in Excel with the various waveforms, and decided to export it to a PDF with notes to help folks understand what is going on. Hopefully you will find this informative!
Adobe PDF, ~500kB
http://www.e30tuner.com/projects/aliasing.pdf
Might be typos in there. I checked, but who knows what I missed in my half-asleep stupor!
i wouldnt expect you to make heatshields or provide the cone filter. i just want the setup to be compatible with it =D keep up the good work and i hope this gets done in time for santa to pass em out!!!
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I tested it more tonight. The converter is now equipped with a filter to try and fix the weird engine-cut I was seeing. The problem at 2400RPM weems to be gone, but the whole floored-at-1200RPM thing is still there. Chances are that the filter has a hard time compensating properly for those intake pulses since they are so far apart. I swear it feels like there is a slightly flat spot between 2800 and 3300RPM, but I might be imagining it. It seemed to go away as I drove...maybe an ECU reset will help. Anyway, I should proably toss it on a dyno soon to see exactly what is up. Tomorrow I will look into logging some AFR's.
Speaking of ECU resets, the stupid car developed a new problem. The Battery Check light now stays on after the car is off. It is completely unrelated to the MAF converter...it must just be life testing me. Stupid car, grumble grumble.
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Hi there, i rally a 318is E30 in the UK and would be very interested in fitting an AFM. I have a rolling road so setting the ECU up would not be a problem (I have a performance power piggy back ecu fitted, so if it requires AFR's changing / ignition timing or injector opening times this would not pose a problem). If you would be willing to sell me the compents / instructions to carry out the conversion please let me know and i will fit it and see what results I can get.
jon finch
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The piggyback you run...do you have the stock AFM input going to it? You could possibly get away with using a MAF and dummy-resistor to simulate the air temperature thermistor, and then tuning from there. Let me know what piggyback you are using and I will look to see if it has the proper signal conditioning needed. The MAF is basically TOO sensitive and is proving to be a real pain on the M42. 6-cylinder motors are easier to use with it since they have some overlap in the intake pulses.
By rolling road do you mean nice back-road, or a dynamometer? I wish I had a dyno...
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Hello there the piggy back unit is a "Perfect Power SMT 6", yes I have do have the stock AFM input going into it and by rolling road I mean a Dyno (lucky eh). If you think a dummy resistor may work, tell me what type and were to put it and i will give it a go.
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Well, IIRC a 1.54kOhm resistor will simulate a temperature of 32.92 degrees Celcius. If you are just tuning based on the dyno and AFR's, then you can pick prettymuch anything I guess. Try to keep the resistance between 1.3k and 3k.
With the unit, do you basically have maps with the AFM voltage along one axis?
Again, adapting a MAF to the M42 is not as straightforward as even I would have thought originally. Being 4 cylinders, the intake pulses actually cause issues at the MAF unit and additional conditioning is needed. I am sure the SMT6 has something built in to deal with a noisy MAF...can you forward me some links to some literature?
I might be able to hook you up with the equivalence data between the 2 sensors for less then the cost of a converter unit since you have already gone to this much trouble. PM/let me know! At this point the information is proprietary just due to the ridiculous $ I have had to spend getting this far, and having done this initially with a partner.
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Well, I was going to ask for a copy of the paper you wrote for your senior project that explained how you were doing all of this but I guess thats not going to happen.
Would something like this help you?
http://www.thatcorp.com/4320desc.html
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Yeah, the paper and a lot of the research is only 50% mine, so giving it away is not really possible. All the new stuff if 100% mine, but much of the sensor data is shared, though I am working alone on this now.
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well how does the m44 do it?
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The M44's DME was designed to use it in conjunction with all the other engine controls, and Bosch has virtually unlimited resources as far as electrical engineering and software. They also have engineers who have done this for a living for....oh hell, they are German, let's leave it at that!!! Lol, it is good to be Bosch.
Now, I am not going to sit here & cry. Once I get a new friggin alternator I can test more. I will make a ~6" velocity stack to try and smooth things out a little. I suspect trying to have this on the air box with that square to round transition plays all sorts of havoc. I might have to toss the airbox compatibility goal. While I wait for an alternator I al finishing up revising the code for my mini-datalogger so I can see exactly WTF is going on with the TPS, EGO, converter input and converter output.
Hokay, bed time!
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Sorry for all the troubles youre goin through bmwman, but all i gotta say is YESSSS more hope for a cone filter setup!!! :D
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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)
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Hmm....wouldn't the conversion be easier if you used an M44 AFM?:rolleyes:
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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?
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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.
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so its still cutting out when u floor it at low rpm's?
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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.
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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
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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?
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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!
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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.
(http://www.e30tuner.com/projects/images/mafcon/hard01.png)
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.
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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.
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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!
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no worries mate,
Out of town til Friday, will do so when i'm back!
cheers
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What did the ford MAF connector look like? I might be able to dig something up.
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It was oval, 4 connector ports, and two locking prongs on one side. If you can find a source of the connector body (with rubber weather gasket on back, and red connector holder insert) and the connector pins, that would be cool!
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do you have a picture of it?