S52 OBDII swap problems (E3 and E4 Peake codes)

[E30s50vert]

I had the same exact issue. For me it ended up being a bad mass air flow sensor. At idle it would only read 14kg/h supposed to be 18kg/h and when i reved it up it would not go past 22 kg/h

[328ijunkie]

So basically both banks are pegging rich meaning either the MAF is reading low or you have a vac leak youre not aware of or your inejctors/fuel system sucks. Youre running pink tops correct? Fuel pressure at idle?

[drulle]

I had the same exact issue. For me it ended up being a bad mass air flow sensor. At idle it would only read 14kg/h supposed to be 18kg/h and when i reved it up it would not go past 22 kg/h

Thanks for your input. I checked and cleaned my MAF, also tested on my friends 328 and it seems to work fine. How can I check it to see what kg/h mine puts out?

So basically both banks are pegging rich meaning either the MAF is reading low or you have a vac leak youre not aware of or your inejctors/fuel system sucks. Youre running pink tops correct? Fuel pressure at idle?

I wonder if CCV is bad.
Pink tops 21.5#
I would check my fuel pressure but not sure how to, will try to look it up online. Thanks for your help.

[328ijunkie]

You have OBD1 or OBD2 fuel rail? Obd2 one has a schrader valve on the end that you can use to check FP.

[drulle]

Finally checked fuel pressure at rail/schrader valve.
It starts at 0 psi and slowly climbs to 41 psi.
It seems to be too low. I took out the fuel pump and saw this:




Is that normal?
I think I need a new pump.

[328ijunkie]

That's normal, though that "connecting pipe" explodes and leaks sometimes. With the fpr vac line disconnected you should have ~51psi of fuel pressure....

[drulle]

Checked my fuel pressure again today with a different (better) tool and everything checked out. I got 52psi with fpr line disconnected. Also installed different CCV and hoses (from a low mileage e36), still same exact issue. Then I disconnected my MAF sensor, check engine light turned on but the motor doesn't bog down now when I give it some gas. So I took it for a spin and it seems to run way better with almost no hesitation and revs past 3k now... what can this be? I'm lost...

[328ijunkie]

Checked my fuel pressure again today with a different (better) tool and everything checked out. I got 52psi with fpr line disconnected. Also installed different CCV and hoses (from a low mileage e36), still same exact issue. Then I disconnected my MAF sensor, check engine light turned on but the motor doesn't bog down now when I give it some gas. So I took it for a spin and it seems to run way better with almost no hesitation and revs past 3k now... what can this be? I'm lost...

Bad maf, very rare but does happen

[drulle]

I swapped MAFS with my friend before. He has a 328is...
My car had same exact running problem with his MAF installed,
and my MAF of his car worked perfectly.
This makes me believe my MAF is good.
I will try another MAF from my other friend's M3... this is frustrating.

[DesertBMW]

Then I disconnected my MAF sensor, check engine light turned on but the motor doesn't bog down now when I give it some gas. So I took it for a spin and it seems to run way better with almost no hesitation and revs past 3k now... what can this be? I'm lost...

This means that all other components including the engine work fine. When MAF is unplugged the DME will then go into alpha-n limp mode and will read a section of a program that is not manipulated by dave the dme tuner. When you plug in back known working MAF and engine does not run right at all, this means DME has hard time understanding the normal maps that were manipulated by non bmw professional.

Next thing what you should do is take your professionally tuned DME and plug it in your friend's 328is and see if you experience same problems on his engine, does not mater if engine is M52 or S52, the DME should run both just fine.

[328ijunkie]

This means that all other components including the engine work fine. When MAF is unplugged the DME will then go into alpha-n limp mode and will read a section of a program that is not manipulated by dave the dme tuner. When you plug in back known working MAF and engine does not run right at all, this means DME has hard time understanding the normal maps that were manipulated by non bmw professional.

I would be happy to show you the fuel maps... If youd understand them..

Next thing what you should do is take your professionally tuned DME and plug it in your friend's 328is and see if you experience same problems on his engine, does not mater if engine is M52 or S52, the DME should run both just fine.

This i do agree with, sort of. It will run fine, but not ideal and fuel trims will do funky stuff if its a M52 flash running S52 and vise versa.

[drulle]

This means that all other components including the engine work fine. When MAF is unplugged the DME will then go into alpha-n limp mode and will read a section of a program that is not manipulated by dave the dme tuner. When you plug in back known working MAF and engine does not run right at all, this means DME has hard time understanding the normal maps that were manipulated by non bmw professional.

Next thing what you should do is take your professionally tuned DME and plug it in your friend's 328is and see if you experience same problems on his engine, does not mater if engine is M52 or S52, the DME should run both just fine.

I will be in contact with Dave to see if we can test my DME for correct MAPs