What else could pull timing?

[QUICKSILVER2002]

I’m noticed some slightly strange timing behavior under moderate load that I have not been able to figure out.

My high and low tables are set the same. The car is a boosted c5 Corvette running the custom OS in SD and the drop in timing only seems to happen around 4000 rpms under decent load. I’ve logged all the timing PIDs and nothing seems to show where the timing is going.

The EST_BASE_DMA PID will show something like 19.2, but the EST_RUN_DMA PID will show something like 16. The SPARKADV PID is a pretty close match to the EST_RUN_DMA.

I’ve logged almost all the other spark PIDs and nothing shows any timing being pulled.

KR
EST - Burst Knock Retard
EST- Coolant Temp Spark
EST - Equivalence Ratio Spark
EST- Induction Air Temp Spark
EST – Total Torque Control Spark
EST – Traction Control Spark

Is it possible for KR to happen, but not show up in the KR PID. I’m able to see KR readings, but not in this scenario.

This is nothing major, but wanted to see if anyone had any other ideas.

[bink]

More info please.
What are your referenced table spark values..High, low octane, base in and out of gear etc?
Did you log "Spark Smoothing"...is it the same reduction in each gear?

[QUICKSILVER2002]

More info please.
What are your referenced table spark values..High, low octane, base in and out of gear etc?
Did you log "Spark Smoothing"...is it the same reduction in each gear?

The base spark pid and the high/low tables match up. It is just that the run spark is a few degrees less.

I did some more logging today(including the smoothing PID) and it did not seem to happen again.

I'll have to keep an eye on it. I did disconnect the batt before the logging today, so I wonder if some type of learned data got reset.

[GMPX]

I suspect it will be torque reduction, these usually seem to be the culprit when going S.D.

Cheers,
Ross

[QUICKSILVER2002]

I suspect it will be torque reduction, these usually seem to be the culprit when going S.D.

Cheers,
Ross

That would show up in the EST – Total Torque Control Spark PID, right?

Anway, I'm pretty sure this was something else. Is there any type of knock learn....? I seem to remember something like that in the past.

[caver]

I had a similar issue but it was KR taking 7 deg away above 3600rpm. It was like a switch.The values in the old knock table got changed somehow during one of the reflashes.
Took me a while to find the cause and caused much swearing and hair pulling.