E36 M3 Turbo getting too much fuel under boost

[Zot123]

I've been trying to figure out this problem for months now after installing my turbo.

Car idles rich (11-13afr) on cold start. Once warmed up afrs go crazy going from one extreme to the other. Under boost the afrs are pinned at 10.0 causing it to break up.

Ive installed an adjustable FPR and is set at 44psi at idle and is solid. No boost or vacuum leaks, ive checked countless times. Spark plugs are ngk 4554 gapped at .24. Coils seem fine after testing. Only codes are mixture deviation in bank 1 as well as cat efficiency in bank 1.

Ive logged it with bmwlogger and my maf doesn't seem to show any values. It is wired correctly and all wires are receiving power. That to me is definitely a problem so i've checked my alternator and idk if its my multimeter is junk but it does jump around a bit but eventually settles at 14-13.8 volts.

Right now im suspecious of the alternator being bad. It is 140amp but an ebay brand the previous owner installed. I just feel the MAF isnt sending a signal to the DME. Ive traced the wires and they all seem fine and undamaged.

I just at loss and any recommendations or thoughts are apperciated.

[MIKYZZ4]

The alternator output seems fine, and as long as non-running voltage at battery every morning is about 12.4v, you should be ok.
If you suspect the MAF, have you attempted to clean it or swap with a used salvage one?
Have you observed engine behavior with MAF plugged in and also disconnected?

[vollosso]

Who is your tuner l?

What happens when you unplug your maf?


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[Zot123]

Yea, I don't want to get a new alternator unless I know for sure it is effecting things.

I'm using RK-Tunes, who I've been trying to get on the phone for a while now with no luck, still trying though.

The MAF (VMP) is new and I've cleaned it multiple times with MAF cleaner. If I unplug the MAF while the car is idling it instantly dies so I know it is doing something, just weird it doesn't show anything when I datalog.

[vr6dubny]

An obvious question I guess but are the correct o2 sensors in the dp and exhaust? Do you have extras from when you went turbo, maybe swap them?

also that is 44 psi with the vacuum line attached I assume.

I am basically going through this same thing but i'm obd1

i wish you were closer i'd let you use my maf to check if it runs better, you know anyone else in the area that has RK?

[MIKYZZ4]

Zit, is the MAF an OE or OEM replacement?
Cheap aftermarket imitations are known to cause electrical gremlins to appear.
Use of OE or OEM quality parts prevent electronic anomalies.

[Zot123]

An obvious question I guess but are the correct o2 sensors in the dp and exhaust? Do you have extras from when you went turbo, maybe swap them?

also that is 44 psi with the vacuum line attached I assume.

I am basically going through this same thing but i'm obd1

i wish you were closer i'd let you use my maf to check if it runs better, you know anyone else in the area that has RK?

I only run the bank 1 o2 in the downpipe and no post cat o2s since RK deletes the rest in his tune. I've swapped between the o2s I had with no difference.

And yes thats with a vacuum line on the FPR. I appreciate that, but yea I've only met a few local turboed m52 and s52s but no one with an RK maf unfortuntely.

I've definitely read a few threads on here with the same or very similar issue but there is never a solution or a clear one at that. I've tried most of the things mentioned in those threads with no success.

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Zit, is the MAF an OE or OEM replacement?
Cheap aftermarket imitations are known to cause electrical gremlins to appear.
Use of OE or OEM quality parts prevent electronic anomalies.

It's not OEM, it was supplied by my tuner and has to be used for his tune. VMP mafs seem to be reputable enough but you never know.

[Vanosthanos]

Did you figure out what the issue was. I am having a the similar issue

[vr6dubny]

My issue was a short in the 5.0V system due to a wire grounding out under the fuse box area.