Knock Retard follows RPM

[vortecfcar]

Hey guys,

Trying to tune an 8.1. With the stock file it's showing significant knock retard. There is no audible pinging.

The knock retard follows RPM to a T, they correlate perfectly. The truck doesn't have any after market parts on it whatsoever (headers ect.). I tried to disable the knock system in the tune so I could drive it an listen for knock. Still retards the same amount of timing.

I'm stumped, are there any other tests I can run to see if the knock sensors are bad, or is anyone aware of what I'm missing in the tune to disable KR.

I've attached the scan and tune file.

Thanks,

Nick

[Ritch]

B6227 is a sensitivity filter that can be adjusted

someone should correct me if that's wrong. Also looks like there is a "learned" knock value somewhere that may need to be zeroed after adjustments, so that there is no KR when the PCM anticipates. Hopefully some more knowedgeables will chime in. I'm playing with the same type of thing

[JezzaB]

Can you log GM.KR instead?

[cmitchell17]

Is it burst knock?

[dc_justin]

Is it burst knock?

Burst Knock doesn't show up as KR, just a reduction in timing.

8.1Ls seem very very KR happy. GM seemed to factor this into the tuning as well, as the maximum timing retard value is set at 5* instead of the usual 8.

[vortecfcar]

Which seems very very odd, considering the log is showin 12.x degrees of Knock Retard.

Maybe we've got a bad PID.

Hmmm....