Massive knock retard with 2650 from 4400 to 6000

[vortech]

I'm confused as to what could be causing all this knock retard. What has me confused is it does it on pump, pump and meth, and even on E. Pretty much at the same spot. 4400-6000. I've tried more timing, less timing no difference. Then I added E in hopes that the extra octane would take it away-no luck. I don't hear anything-I'm certain this is false. It goes away after 6k. It is a little on the rich side but it doesn't really seem to matter at this point.

Here is a log and tune.

Any guidance would be appreciated-TIA!

[cadillactech]

You are commanding .85 but your wide band is showing as rich as .79 lambda.

Have you tried leaning it out? If a conservative spark advance does not change the amount of knock and increased octane doesn't either, most likely too much fuel is causing the false knock.

I tired opening your calibration file but there was an error.

[vortech]

I've attached another tune and log-this time i turned off the knock sensors. Result was no knock-I also recorded a tailpipe video and no "puffs" were visable. Something is making the knock sensors go off but I don't know what. I don't hear or feel anything.

[HardH20]

Cant see your other log with the knock but I've been working on a C7 with a hell of a knock also. Installed an A and A kit and headers gets a lot of knock up top only. Completely desensitized knock sensors to like 16 and all knock went away. The car had a noise when it is shut off-before the install. Sounds like a double knock. Come to find out the rear coupler is bad on the driveshaft. Removed the rear torque tube cover and can move the flex plate and torque converter with my fingers like 60 degrees. The engine side flex plate does not move at all when this happens. Told customer we have to replace the coupler before any more tuning can be accomplished-a quick check you can do. I've only seen the front couplers go out on these cars before.

[vortech]

Cant see your other log with the knock but I've been working on a C7 with a hell of a knock also. Installed an A and A kit and headers gets a lot of knock up top only. Completely desensitized knock sensors to like 16 and all knock went away. The car had a noise when it is shut off-before the install. Sounds like a double knock. Come to find out the rear coupler is bad on the driveshaft. Removed the rear torque tube cover and can move the flex plate and torque converter with my fingers like 60 degrees. The engine side flex plate does not move at all when this happens. Told customer we have to replace the coupler before any more tuning can be accomplished-a quick check you can do. I've only seen the front couplers go out on these cars before.

It's funny you mentioned the torque tube. My car is C7 Z, the torque tube is actually carbon fibre and the transmission end was broken. Since I mostly drag this car I did not see the need to replace it with another CF Torque tube to save the 15lbs-so I replaced mine with a regular C7 torque tube but swapped the insides. I've seen 2 CF torque tubes actually break now where they go into the bellhousing on the transmission end. I know we checked everything but this might be worth looking again. It's jsut weird that we don't hear or see anything on dyno pulls.

[cadillactech]

It's funny you mentioned the torque tube. My car is C7 Z, the torque tube is actually carbon fibre and the transmission end was broken. Since I mostly drag this car I did not see the need to replace it with another CF Torque tube to save the 15lbs-so I replaced mine with a regular C7 torque tube but swapped the insides. I've seen 2 CF torque tubes actually break now where they go into the bellhousing on the transmission end. I know we checked everything but this might be worth looking again. It's jsut weird that we don't hear or see anything on dyno pulls.

Could be something for sure. Those torque tubes make so much noise when the bearings fail.

Did you try leaning it out? These DI motors will "knock" with too much fuel in the combustion chamber.

Your injector pulse width is approaching the limit of time you have to actually inject fuel before the piston starts rising again. Leaning it out should drop it.

What fuel system do you have on this car?