1997 m3 CEL help!

[m3f_98M3csm]

How many miles on that head gasket before you replaced it?

[m3f_Duvany]

I'm not sure. I say that because it looked almost as though it had already been replaced before because it looked like it was in ok shape. If it was original, then 127k or so.


I'm probably going to replace the crank sensor soon.

[m3f_vmbray]

I'm not sure. I say that because it looked almost as though it had already been replaced before because it looked like it was in ok shape. If it was original, then 127k or so.



I'm probably going to replace the crank sensor soon.

How confident are you of the vanos timing? Did you engage the first tooth? Did you meticulously follow the cam timing instructions? Which instructions did you use? Did you test vanos advance with air?



Vanos can affect the engine in all kinds of ways, starting, idle, running, power, etc.



If you have inpa, hook it up and see if cam is advancing at around 4200 rpm.

[m3f_Duvany]

hey vmbray, sorry i havent been on in quite some time.


i am confident in the vanos timing. I took great care to inspect and understand how it should be prior to removal, and i used a hayne's manual (i believe). I did not test the vanos with air however, and i dont have inpa nor do i know what that is lol.


the issue is extremely subtle and is not constant. I did some reading on the car's motronic system and i read that the computer draws information from the obvious sensors like cam and crank shaft etc, but that it also takes into account the exterior temperature sensor along with the intake air temp sensor. does this sound familiar to you? because my ext temp sensor is missing.


the car does not have the problem at all when functioning on an open loop, and is only present 65% of the time, at idle, during closed loop. if i havent stated before, my O2s, cam and crank sensors are all new, but im continuing to receive check engine code for fuel air metering (the car also had this code prior to HG job).


I have not been able to find anywhere if the ext temp sensor influences the motronic system, but that will be my next step since its missing anyway.


let me know if you guys have any insight.


Cheers.

[m3f_Duvany]

So after recently running my codes again, im still getting the 1188 Fuel air metering, along with a few random misfire codes and a pending O2 no circuit activity code.


Running I/M monitors, I'm reading that my O2s, cats, and secondary air system are coming up as incomplete.


My dad's 06 ford f150 had a very similar problem due to a corroded computer module that ford was dumb enough to put under the bed by the spare tire, open to all the elements. Does the e36 have something similar to this?

Once replaced the car was running better and of course could now pass NJ inspection.

[m3f_Duvany]

So after recently running my codes again, im still getting the 1188 Fuel air metering, along with a few random misfire codes and a pending O2 no circuit activity code.



Running I/M monitors, I'm reading that my O2s, cats, and secondary air system are coming up as incomplete.



My dad's 06 ford f150 had a very similar problem due to a corroded computer module that ford was dumb enough to put under the bed by the spare tire, open to all the elements.

Once replaced the car was running better and of course could now pass NJ inspection.



Does the e36 have something similar to this?

[m3f_englishtom1596q]

E36 Computer is passenger firewall and sealed away nicely. Did you replace all the gaskets as you rebuilt? Valve cover gasket, intake manifold gaskets, idle control gasket, throttle body gasket etc? Also did you inspect your knock sensors? They're known to disintegrate of old age and give all sorts of weird running and ecu problems.

[m3f_Duvany]

All gaskets were replaced yes.


Knock sensors were not replaced but they looked fine.


Since the last time I disconnected the battery I've driven a lot of miles, but could it be that I just haven't completed a proper drive cycle for the monitors to reset? And if the monitors don't reset and list as ready, could that cause my problem?

I know the drive cycle calls for moderate ambient temp, but is that for the process or does the computer actually need to note what the temperature is in order for the drive cycle to work? Because if that's the case I would only need a new ambient sensor and to complete a drive cycle.


It's definitely a closed loop problem

[m3f_Duvany]

going to purchase and replace ambient temp sensor and intake air temp sensor sometime this week.


also will try to clean the MAF in case thats affecting the problem. i read somewhere that if i disconnect the MAF and the problem goes away, then my MAF is the sensor screwing with the appropriate a/f ratio. any insight?


thanks guys.

[m3f_Duvany]

Problem is still unresolved. I have since just been running the car in constant open loop by leaving there-cat O2 sensors unplugged. The car has been driving normally with an even higher mpg (22-23). But recently (I'm guessing due to the colder weather) the car has randomly had lumpy acceleration that only goes away after shutting off and restarting after about a minute.


This leads me to my question. Could the cats be clogged? The O2 sensors were altering a/f before but now they are so bad that there is a problem even in open loop?


I am going to clean the maf and icv this Sunday to put that doubt away.

Hopefully I will be able to inspect the cat as well.


Is it possible I just need a new dme, or a reflash at least?


I want to put this to bed and I'd rather not spend hundreds diagnosing at a shop, but I will undoubtedly do it if I can't find the problem soon.


Thanks for any help guys.

[m3f_Duvany]

does anyone have a clue?


that lumpy acceleration when cold turned into limp mode on cold starts, but only sometimes. have no idea whats going on anymore.


code p0170 for fuel trim malfunction (bank 1)

pending code p0134 o2 sensor cot no activity (bank 1 sensor 1)

[m3f_boomersooner523]

Long shot here but have you tried changing the fuel filter? I don't think it could be your issue but I once had a bogging issue in one of my old E36 M3's and the fuel filter did the trick. For $20ish and an easy DIY makes for a "why not" situation.

[m3f_Duvany]

Thanks for the reply.

I actually have a new fuel filter I never got around to putting in. I'll do that as soon as I have time.

I feel like my cats might be clogged though, not sure if anyone has any insight as to what symptoms that would cause. I read somewhere that my dme needs a reflash and that could fix the new limping problem as well as my closed loop issue.