I have a 89 iroc 350. The car has new heads, new headers, new cam, etc. I had the car running great. I had a 14 second car. The BLM's were very low, but not out of range. The o2 values looked perfect. .5 low throttle around .85 wide open. Suddenly the engine died one day on the way home from work. Now it is rich as can be. I have to hold the foot feed all of the way down when cranking, to start it. When it is given any throttle it will hesitate or die, and kick out a plume of black smoke. The o2 reads .9 all of the time. Does anyone have any ideas?

 

after more data logging, I find that it is not going into closed loop. I do not know what would stop that.

 

Sounds like the fuel pressure regulator died. Remove the vacuum line from it and turn on the key (engine off), check for fuel spilling from the vacuum port on the FPR.

It may be a MAF issue, however, the MAF isn't used during cranking. So that should rule out the MAF.

RBob.

 

thanks for the reply, this site has been the best help ever. I found out what it was. The computer was staying in open loop, and the CTS sensor is what was doing it. It failed but not all of the way. It was telling the computer that it was zero degrees engine temp. When the sensor is unpluged it goes to -38. So I did not get a code for 0. Thanks for the help.