Spark issue with ZL1 Camaro ?

[TheCreature]

Tuned this zl1 camaro with long tubes, rotofab intake, bosch 850s, pulley, and ported throttle body. Everything was fine on the dyno with AFR around 11.5 at WOT. No issues so to speak. Now the guy says the car is breaking up and sent me some logs. Its showing some knock activity then going into negative spark at WOT. I don't know what direction to point him in. Car ran flawless for 6+ months. Seems like a mechanical issue, but what. On this latest log I added some fuel just to test, but its still doing weird stuff at WOT. Log and tune attached. Let me know if you guys see anything. Thanks!

r18.hpl

Dave zl1 r18.hpt

[schpenxel]

Have him log every advance/retard parameter he can find.. one will stand out pretty quick I bet.

[jsllc]

Start with knock. You have some huge knock counts. Log all timing. MAF is also not calibrated for your CAI. AFR gets to 12s under boost. Last thing near the end of the log it says 255KPA of manifold pressure with 22lbs of boost. I doubt it.

[schpenxel]

What is weird is I really don't see anywhere in the log where knock is that high when looking over a chart of knock retard..

But the knock retard graph I'm using looks about as bad as the one you posted, shows 16+* in some spots

Weird.

Maybe I just missed it when I was flipping through the log

[JBZ]

so im seeing zero ACTUAL KR but total KR in 17 degree range, not once in the log did I notice actual KR. thinking you have burst KR or something else triggering it. obviously that would be why you are seeing negative timing. not in the range of -15 though, Burst KR would put you in the zero range. looks like you made high and low octane tables the same so this car has nothing to reference when it actually does see real KR...just an observation.

[schpenxel]

There were some spots with knock.. just nothing like the numbers in the graphs are showing for some reason? Weird

[JBZ]

There were some spots with knock.. just nothing like the numbers in the graphs are showing for some reason? Weird

yeah and total KR is super high when no real KR is shown...it is weird

[ABADZL1]

Is this car currently running the same tank of fuel since this all started? This is the same problem on another ZL1. His was all stock. It ended up being crappy California 91 octane fuel. He went round and round with the dealer for quite a while with popping, pinging and logging lots of knock with dash logic. They finally tested the fuel and said it wasn't good. He had his car professionally tuned on Calif. gas and solved that problem. I thought of him when I saw this post. You described his same problem to the T.

[TheCreature]

Just an update, looks like this is a clogged kooks cat.