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

 

I would start checking the wiring.......

 

Investigating further I discovered that if the ECM does not detect a signal from the knock sensor, it will retard the timing to the maximum allowed in the program. So that's the answer.

Being that its intermittent and that unplugging the chip and plugging it back in makes it go away for a while, I'm thinking that the calpack is bad. Its been years since I fooled with this stuff and from what I remember, the ESC circuitry is in the Calpak itself.

I'll burn another chip in my spare Calpak and try that first.