Been fighting my turbo setup... long read...

Ive asked people in the Grand Prix community directly but everyone keeps telling me to switch to the 98+ PCMs (which has better knock recognition stuff). When I was running a mid 12 second supercharged setup I never had any issues like this. Randomly one day it appeared and its been here since. Something electrical, mechanical, spiritual... . No idea. Ive eliminated pretty much EVERYTHING that could be physically tapping on the motor to create false knock.

The problem is at VERY low throttle percentages (1-2%) I get knock (typically less then 1 degree) but sometimes as high as 5-10 degrees of knock. I threw in a couple gallons of race gas and the knock was still present so Ive ruled it out as false. At WOT I seem to get completely random knock (which could or could not be related to the partial throttle knock). I get knock as low as 7psi (limited by the spring in my waste gate) which is very little boost.

Did a compression test came back good. All cylinders read 130-135 after 3 seconds of cranking, all cylinders read 160 exactly after 5-6 seconds of cranking. All of my plugs looked slightly white when I pulled them. Running lean? According to my wideband Ive been running pretty rich for the last month or so at WOT (mid 10s).

Went over a bunch of my wires again and actually found some wires in the back that were rocking back and forth and the shielding was melting on my rear manifold. Its the wires that go down the back of the motor to the sensor on the diff cover and to the knock sensor.

Anyway, went out and drove around thinking that it couldve been the cause of my partial knock and possibly some of my WOT this whole time but it wasnt. Still have it... and my car still seems to knock at WOT with only 13-14psi and 16.5 degrees of timing. Im running a high 10 to low 11 AFR right now.

Threw a code for my crank position sensor the other day so I went in and replaced it and did a case learn with my tuning software. Knock was GONE for a day or two except blips of .01 at partial throttle sometimes. Over the course of the last couple of days its been slowly returning... maybe Ive got a stretched timing chain? Im running an aftermarket "unstretchable" double roller timing chain so Ive been scratching this off.

Ive got a setup capable of 18-20psi with a pretty big intercooler. Running 65# injectors, aftermarket racetronix pump, a pretty big cam... and at wide open throttle its verified by my wideband that Im not going lean or anything which could be causing it. Ive replaced all O2 sensors and a ton of sensors on the motor since I had a lot extra (MAF, TPS, IAC, knock sensors, MAP sensor).

Ya, I know you guys arent use to working with my stuff, but I figured Ide copy and paste and see if anyone had some insight.

The problem is at VERY low throttle percentages (1-2%) I get knock (typically less then 1 degree) but sometimes as high as 5-10 degrees of knock. I threw in a couple gallons of race gas and the knock was still present so Ive ruled it out as false. At WOT I seem to get completely random knock (which could or could not be related to the partial throttle knock). I get knock as low as 7psi (limited by the spring in my waste gate) which is very little boost.

Did a compression test came back good. All cylinders read 130-135 after 3 seconds of cranking, all cylinders read 160 exactly after 5-6 seconds of cranking. All of my plugs looked slightly white when I pulled them. Running lean? According to my wideband Ive been running pretty rich for the last month or so at WOT (mid 10s).

Went over a bunch of my wires again and actually found some wires in the back that were rocking back and forth and the shielding was melting on my rear manifold. Its the wires that go down the back of the motor to the sensor on the diff cover and to the knock sensor.

Anyway, went out and drove around thinking that it couldve been the cause of my partial knock and possibly some of my WOT this whole time but it wasnt. Still have it... and my car still seems to knock at WOT with only 13-14psi and 16.5 degrees of timing. Im running a high 10 to low 11 AFR right now.

Threw a code for my crank position sensor the other day so I went in and replaced it and did a case learn with my tuning software. Knock was GONE for a day or two except blips of .01 at partial throttle sometimes. Over the course of the last couple of days its been slowly returning... maybe Ive got a stretched timing chain? Im running an aftermarket "unstretchable" double roller timing chain so Ive been scratching this off.

At wide open throttle its verified by my wideband that Im not going lean or anything which could be causing it. Ive replaced all O2 sensors (including wideband) and a ton of sensors on the motor since I had a lot extra (MAF, TPS, IAC, knock sensors, MAP sensor).

Have you ever replaced your knock module in the pcm with an updated one from the dealer? Tried a different pcm?

I have NOT tried a PCM. The only other knock module I have tried was an LT1 knock module (which just threw a code).

Updated knock module? Did they have newer revisions of them? I know some people say we can use the LT4 knock module but I didnt want to spend 50 bucks on one just to have it throw a code like the LT1 did.

EDIT: I had some extra sensors laying around... Ive replaced my wideband O2, my narrowband, TPS, IAC, MAFF, front knock sensor, CPS...

Did you repair the wires that were damaged? Follow the wiring all the way back to the PCM looking for issues?

Was the Double roller setup corrected before install, cause the gear on the crank can crack under the pressure if it isn't chamfered(i think thats the word) correctly. there was another member on one of the boards that the thing cracked almost in half......
Sounds like it is something around the CPS area, maybe something you moved when you swaped it out and moved itself back after driving??

Good point on the timing chain since you are using the double roller. Also there was an interference issue with the chain rubbing on the oil pump cover.

Originally Posted by 02BlueGT

Was the Double roller setup corrected before install, cause the gear on the crank can crack under the pressure if it isn't chamfered(i think thats the word) correctly. there was another member on one of the boards that the thing cracked almost in half......

That would be me....and it did crack in half.
And surprisingly, I drove it home in that condition.

I went over my knock sensor wires last night... all were good but I found one that fell apart pretty easy. Fixed it, its still giving me partial throttle knock though.

reptile, did it give you any kr?

I didn't get any KR, no....but it made a hell of a bad noise....it sounded like the IAC on the wrong end of the engine. It held up on a 40 mile drive home, then it fell apart on me when I tried to line the engine up at TDC.

It's now sitting on my desk as a reminder from now on.