idlebumski

Was trying to determine why surging idle so uploaded another tune, and immediately got CEL P0102 (Low Voltage MAF), hot smell like when headers were brand new, still idles very badly, but once catches its breath. pulls like not supposed to, gobs of torque, sometimes cuts out maybe to protect itself.

Installed new MAF, code gone immediately, car runs fine again, but back to very conservative power.

So I took the new MAF out and put the 'bad' one back in, CEL, thrilling torque, but bad idle and sometimes cut out or off again.

Not sure what is wrong with bad MAF, but it is like race tune.

Hot smell suggests running lean... The extra torque obvious on startup, car dips more sharply when lightly blipping throttle at standstill.

Anybody else same experience, and/or am I going to destroy the motor running it like this?

brauhaus313

With the bad MAF you're running open loop. With the good MAF you are running closed loop. If your performance drops off that much between going open and closed loop, you likely have a running issue while running closed loop that is not bad enough yet to throw a code, but is affecting your performance. Long term it is not a good idea to run your engine open loop all the time. If you are unfamiliar with what open loop and closed loop mean, there's plenty of info online.

Viper98912

Is the MAF an MB/OEM branded one? I remember hearing that aftermarket MAFs (even if almost-the-same) could cause issues on these engines. I replaced the MAF once or twice when I had my C55.

idlebumski

yea, the bad maf was a bosch unit. the car would be perfect like this, except that it does cut off completely very occasionally, which is dangerous.