Been dealing with a very strange gremlin as of late. The camaro when it is warm and under a heavy load, say getting on the highway seems to lose all its advance timing and pulls like a slug. And until I shut the car off it will accelerate like a slug (side streets, highways...).

I can tell right when this is about to occur because the Camaro pulls really hard then almost feels like it shifted into neutral the acceleration is stopped so suddenly. The exhaust note drastically changes to a flat note, and the rpms barely move.

My transmission guy rode along with me and told me this isn't a transmission related issue but a timing issue. On a guess I replaced the ESC Module and that did not fix the issue. Only other thing I can think of is a bad PCM.

Anyone have any ideas?

 

Sounds like the forced knock test is failing. This should also turn on the SES light with code 43.

What you are feeling is the ECM adding SA to force the engine to ping or knock (the hard pull). The ESC system will (should) report that to the ECM. Where it sees it and says, OK, ESC system is functional.

If the knock doesn't get reported the ECM says the opposite and pulls a set amount of SA until the key is cycled.

RBob.

 

Hmm, ses light doesn't work so I have no idea if I have a code set or not. But I have a brand new ESC module on the car and the issue is still there. I am looking at the flow chart for the code atm, and the options are faulty wiring or the ecm at this point. And thats if I have a code 43.

 

Okay, after not being able to work on the car for a couple weeks I have some updates. I have a dtc code 43.

I am reading that a loss of the ESC signal to the ECM will cause the ECM to constantly retard the timing to its maximum. Which sounds like what is happening to my car.

As for the actual esc functional test, at WOT with the engine temp above 194* the computer adds a ton of spark advance (This is what I feel as though the car gets an unusual burst of power) until it detects a knock. If it does, the test is passed and there are no problems. If the computer doesn't detect a knock during the test, then it will retard the timing to its max.


I read that using high octane fuel (I use 93) can also cause this code to set. And I am wondering if my piggybacked chip could be causing issues as I have the original 305 chip piggybacking a JET chip for an 87 camaro with a 350.

After I replaced the esc module it sometimes passes that functionality test. Where on the highway at WOT, it will pull hard (the test is being applied), then the timing will be retarded (fails test), then come back and pull again hard, only for the timing to be retarded at maximum again. From then on the spark advance is non existent until I shut the car off.