C7Z - all stock, lots of knock!

[kjlindgr]

Looking for some thoughts on a 2017 C7Z that was brought in with "low on power" issues. Apparently the dealer replaced knock sensors and the ECU due to CELs while under warranty. What I'm seeing is that under load, the engine is pulling between 6-8 degrees of timing steady throughout the pull. I verified fuel is good with a wideband. Vehicle is completely stock. I added 5 gallons of 100 octane thinking it may be a bad gas situation - no change. I pulled plugs on DS bank, they all looked OK. I can periodically get it to throw a P0325.

Below is a log of what I'm seeing. Seeing it pull timing across all cylinders. Actually recording knock on pistons from each bank.

'Any thoughts on what may cause a completely stock car to have this kind of issue?


2020-05-14_0114.png




RUN_KR4.hpl

[godzilla420]

you check your fuel pressure?

[kjlindgr]

you check your fuel pressure?

If you can believe the fitted sensors, everything is kosher. Are you suggesting that they are not correct?

[TriPinTaZ]

You sure its 100% completely stock? Stock crank pulley? Stock TB and non ported blower?

[kjlindgr]

100% stock...even the air filter.

[TriPinTaZ]

crappy gas or incorrect spark plugs or plug gap would be my first guesses

[kjlindgr]

Spark plugs are OEM AC Delco 41-128 plugs. I was thinking of swapping to colder ones as something to try.

Car has about 21K miles on it. Are there any known issues with injectors clogging or anything like that?

[TriPinTaZ]

Check the CATs to make sure they are not damaged but also have you verified the knock sensor wiring is not damaged? You may need to trace the path all the way to the ECU.