I am getting a code 55 from my 1993 Z28. The check engine light came on at the end of a 1/4 mile pass, then went off as soon as I let off the throttle. The only thnig I can find on a code 55 is "ECM error". The car runs fine. Any ideas?

 

55 = Fuel lean monitor (you can view applicable codes from the link in my sig). It means the PCM is seeing a lean condition from the O2. A couple of things it could be is inadequate fuel pressure from a poor flowing fuel filter or dying pump.

 

Thanks. That makes sense. At the track last weekend I was turning 85 mph in the 1/8th, but only 102 in the 1/4.