CEL Please help, I'm stumped!

[cooljess76]

Alrighty, Here goes. I have a '97 318ti Sport with the OBDII M44. The car has a new motor with 25k miles on it. While driving the car from Michigan to California the Check Engine Light came on. The car was running great so I didn't stop. I drove through some really rough weather(snow, ice, etc). On the way there the heater stopped working and the temp gauge began to rise. I shut her down and pulled over immediately, the gauge didn't make it to the red. I found that I had a case of air lock in the cooling system. I burped and topped off the radiator at a gas station and continued on my way. The heater worked fine. When I made it home to California, I checked the coolant level again and it was about a gallon shy. I burped the system again and all is well. Except for the CEL and I can't find out where the coolant is going. I checked the coolant for oil and the oil for coolant and everything looks fine. The car runs great with no performance loss or idle fluctuations. So I go to Autozone and borrow the OBDII code reader. It gives me the following codes: Cyl 2 misfire, O2 sensor circuit bank 1 sensor 2, and manufactuer's controlled air fuel metering. I remember driving over chunks of ice and I felt them hitting the undercarriage. I couldn't swerve to avoid them as I was on ice. I looked at O2 sensor #2 and found that it was cracked. I was sure that this was the problem so I ordered a new one. I also found that the rubber ribbed duct going into the throttle body had a split in it. I repaired the duct with epoxy for a temporary fix. This got rid of my cylinder misfire code. I checked the air filter and it was brand new. I checked the plugs and they are white which indicates that the car may be running a little lean. I finally got the O2 sensor and installed it. Borrowed the code reader again and cleared the codes. I took the car out for a drive on the freeway and everything was great. Once I exited and headed home the light came back on. The next day I went back and checked the codes again and the only code it had was the Manufactuer's controlled air fuel metering. The O2 sensor #2 and the Cylinder 2 misfire codes have not returned and I've driven the car about 500 miles with no smoke, clean oil and clean coolant. The car idles fine and drives great. I still have to add coolant regularly but the temp stays dead center. Of course I've considered a blown headgasket, but it's a relatively new motor with only 25k and 3k on the check engine light. The car runs great and I don't know where to look next. Any advice would be great. A case of beer goes out to the winner. Will someone PLEASE HELP ME fix this thing, it's driving me nuts! Only one code left "manufactuer's controlled air fuel metering" Thanks in advance, Jess

[DustenT]

Controlled air metering would make me thing MAF (mass air flow) sensor. Fix the cracked boot, it's a cheap part, like $30 from the dealership. Any kind of leak after the MAF (located between the airbox and throttle body, attached directly to the airbox outlet) will cause errors.

If that doesn't solve your problem, find someone locally that will swap MAFs with you. You won't do any damage and neither will they, but if the code appears on their car, you know the MAF is bad. That's really the only way to test that thing.

[cooljess76]

Thanks Dusten, I was going to replace that boot, but then when I thought about the cost I considered building a CAI or a shielded short ram. How cool would it be to run an A/C duct into the airbox.

[cooljess76]

I was thinking about spraying something around that boot to see if I could get an idle fluctuation or something. If that doesn't work, I'll try the MAF. Thanks again.

[mooseheadm5]

Carb cleaner will work for that. You need a better code reader to figure out what is up if there are no more leaks.
-Paul

[scabzzzz]

you got a lot of pulls on bimmerforums. dustinT is right though. its gotta be maf related it sounds like. see if you can get a code read from a bmw specific scan tool though to get a better idea after doing the maf deal