10* KR during pull

Hey all, I was attempting to VE tune and was doing a 1/4 mile today in my 2002 LS1 corvette(383 H/C/I/E) and logged the following run. Now I know the VE table is fucked up, and I have corrected that. My confusion comes from the fact that the KR only appears in 4th gear, at 4500rpm. Wouldn't any KR come into play at the same rpm, regardless of gear? It's a manual. The car fell on it's face in 4th after relatively clean 2nd and 3rd gear pulls. Thanks for taking a look.

Attachment 141967Attachment 141968

Edited to add: No DTCs popped up during/after the run

Second edit: Just realized my burst KR tables are stock. I had created a new file when going from my 5.7 tune to my 383 tune and didn't copy over the burst knock table...looks like I just needed a rubber duck to talk to. Will log and report back.

It would be most helpful to log cylinder airmass in order to really know what is going on with anything spark related, as rpm is only 1 of the variables.

That's not burst knock. That looks like real knock. It's 2 degrees more than your burst knock table at that RPM and it's happening right about at peak torque. I'd be looking at fuel, spark plug range, type, etc.

It's way too rich through that range also. That's part of the falling on its face feeling, not just the timing.

Log cylinder airmass as gametech said. Otherwise you won't know where you are in the spark tables.

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Originally Posted by edcmat-l1

That's not burst knock. That looks like real knock. It's 2 degrees more than your burst knock table at that RPM and it's happening right about at peak torque. I'd be looking at fuel, spark plug range, type, etc.

It's way too rich through that range also. That's part of the falling on its face feeling, not just the timing.

Log cylinder airmass as gametech said. Otherwise you won't know where you are in the spark tables.

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The airmass during the knock event is 95g +. I've narrowed it down to only happening under full throttle in 3rd or 4th gear. The plugs are ngk tr6 with a gap of 0.035. Fuel is full 91.

I also did a run with the spark table retarded 10 degrees globally, and same thing happens. Maybe I'm blowing the spark out of the plugs? I'm going to gap them to 0.025 and see what it does.

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Originally Posted by rileymeekpierce

The airmass during the knock event is 95g +.

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How do you know that if Cylinder Airmass is not being logged? Or have you since added it and just choosing not to share any more logs with the people you're asking to help you?

Hey blindsquirrel,
Thanks for the reply. I had just finished a log today, as it's been the first day sunny in a week since I first posted, and was eager to share, so I posted from my phone without a log attached. Here's the tune and log for the car. This was the tune with retarded timing, and this log for that tune shows airmass as well.

Attachment 142198Attachment 142199

If it's a forged piston engine you have a lot less to be worried about. You can approach it differently. If the engine is new and you know the compression ratio and you're confident it's accurate, best thing you can do is dial in the rest of the tune, put it on a dyno and add timing until the returns diminish. Dumb down the sensors til they stop pulling. But you need to be confident the fuel is fresh and good and the octane is correct. Spark plugs are proper heat range, all that stuff.

Quote:

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Originally Posted by edcmat-l1

If it's a forged piston engine you have a lot less to be worried about. You can approach it differently. If the engine is new and you know the compression ratio and you're confident it's accurate, best thing you can do is dial in the rest of the tune, put it on a dyno and add timing until the returns diminish. Dumb down the sensors til they stop pulling. But you need to be confident the fuel is fresh and good and the octane is correct. Spark plugs are proper heat range, all that stuff.

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It is a forged wiseco 2618 piston, Callie's compstar rod, k1 4 inch crank motor. The engine has maybe 200 miles on it, just dumped the break in oil and filled it with full synthetic. I may convert to e85 just to ensure I have enough octane, but the motor should be at 10.4 to 1 ish compression - not much at all. You think just turn off the sensors and just pound it in?