strange KR spike at WOT

[87gtNOS]

05 C6 LS2 cammed....made 2 runs...1st run with hotter IAT had zero KR and zero burst retard...2nd run had 5 deg KR when I went WOT at 2000rpm (which is how I do every run) and declined with RPM.
Pic of scanner with the timing retard circled in Yellow.....and I will upload tune and log. Weird.

Actual outside air temp was 25c (77C) with the humidity over 30c (80's F!!)

[Alvin]

That's not very strange. That's how knock looks.

It could be noise from a violent launch. or it could be actual knock. If you can repeat it, try to reduce timing in that spot.

[Cringer]

The real problem is that you are initiating WOT at 1,800 - 2,000 RPMs. I assume this is a manual car and without an unlocked torque converter to allow the RPMs to flash higher, this is just a recipe for knock. Don't do this, it is too much load on the engine.

That being said, there was a knock event that initiated the spike from the knock sensors (which is good for you). Then you can see a slow and gradual sloping decline from the recovery and during the recovery it does not spike again. This is due to conservative settings in the [ECM] 12744 - Knock Retard Recovery Rate table. If you make those numbers larger when you see knock it will spike and then drop down almost immediately so you don't sacrifice too much power waiting on timing to be restored. I am not suggesting that you go crazy on this table, but you can play with it. If you see an initial spike, a recovery, and then another spike(s) forming, then you know there are several knock events that have occurred during the recovery phase. It is normal to see some amount of knock.

Here is a screenshot showing a much faster recovery rate from knock. No gentle slope.

knock.jpg

[87gtNOS]

The real problem is that you are initiating WOT at 1,800 - 2,000 RPMs.

knock.jpg

Are you saying was likely caused by going slow and whacking the throttle WOT at 1800ish rpms? I have not replicated the knock.

[Cringer]

Are you saying was likely caused by going slow and whacking the throttle WOT at 1800ish rpms? I have not replicated the knock.

Yes exactly, low RPM detonation is way more common than high RPM detonation. Placing the engine under that much load is also very hard on the rings and will accelerate ring and upper cylinder bore wear in addition to detonation. If you do this all the time and don't see knock then you are lucky IMHO. False knock also happens from a bump in the road, exhaust hitting the chassis, suspension noises, engine mounts, chassis resonance, etc...it just happens.