commanded afr jumping around and going very rich on 2002 Fbody

[JASON11WS6]

I have a customer with a cammed trans am. We were suppose to swap the heads and do a retune. First pull on the dyno and the car is going very rich. The commanded afr is set at 12.95 but it never sits there. As soon as we enter power enrichment it jumps to 12.4-12.6 and then plummets from there. It'll go as low as 9.8 before bouncing back up some. The car runs fine normally and the afr sits at a flat 14.63 while cruising.

Catalyst protection is disabled, I even zeroed out the tables just in case.
I zeroed out the eq ratio subtractor


Any ideas?

[JASON11WS6]

Check that on the cruising. Seems to sit in the 12s and 13s during normal driving.

[village_idiot]

Post the file?

[JASON11WS6]

OMARS.CAMMED.TRANSAM.004.hptOMARS.CAMMED.TRANSAM.004.hpl

[JASON11WS6]

So I found the coolant temp sensor is causing some of it. When it drops the temp the afr drops big time. But it's still bouncing around before that too

[4.great_cobra]

So I found the coolant temp sensor is causing some of it. When it drops the temp the afr drops big time. But it's still bouncing around before that too

Did you ever get this problem completely figured out?

[blindsquirrel]

The PCM can see and react to 'noise' from a bad sensor/wiring that will not necessarily show up in the scanner.