89vette

I just developed a strange Code 43 problem. When the SES light comes on indicating a problem, it retards the timing either 6 degrees or 20.1 degrees with no rhyme or reason. I'm running a gm speed density ECM so I have the correct knock sensor plus its wired directly to the ECM bypassing the ESC module. It's worked fine for years. I have to look but I think 20.1 degrees is way more then I allow for max spark retard.

Would a faulty knock sensor allow this to happen intermittently? This has me stumped because of the steps of 6 degrees and 20.1 degrees. Furthermore, the knock counts do not increase when it jumps up.

Thanks,
Jason

Calderone

Might be a possibility,try another one,i replaced all my sensors just to be sure
i've seen faulty Knock sensors hurting performance,check for loose or dirty wiring as well.

89vette

In investigating further, I found that the ECM will retard the timing to the maximum allowed when no knock sensor is detected. That explains the 6 degrees with the jump to 20.1 because that is what my table allows. If I pull the Cal pack and plug it back in, it runs fine for a while. I'm thinking the problem is in the Calpack itself where the ESC circuitry is for the speed density systems.