If I log my car, I get around 7 degrees of knock retard starting at the bottom of 2nd at WOT (~4000 RPM). At 5000 or so, the KR drops off and pretty much disappears by 6000. There is no KR in 1st gear. I know at least some of the knock is false, because before I put the LT4 KM in I was seeing like 10 degrees. Putting in the KM smoothed it out quite a bit. My trap speeds also went from 100 to 102 after the KM.

What could be causing my problem?

 

TTT

 

My knock was caused by a spun bearing.

 

-low octane fuel

-carbon buildup in combustion chambers

-excessive inlet air temp

-excessive coolant temp

-lean A/F ratio

-too much spark advance

Have you run some 100-octane unleaded to see if it helps?

 

Thanks for the suggestions Fred.

Regarding carbon buildup in the combustion chambers, the motor does have 138k on it. Should I run some seafoam through it?

Inlet air temp is pretty cool. I can't remember exactly what it was but it was ok.

Coolant temp never gets above 187 degrees or so.

I'm not sure of the A/F ratio. The car only gets 16 MPG at best...

Spark advance. Bryan at pcmforless pulled quite a bit of timing out of it to see what that did, and it dropped the KR to around 5.5. So there was less KR, but it was still there.

I always run 93 octane, so that can't be it. I will try some 100 octane when my tank gets low in a couple days. If the KR goes away, then it's real knock right?

 

Fred this reminds me. I don't know if you remember arguing with me about flow #s with CAI's, but when I switched to the GM CAI my knock is at 0 at all times (might go to 1 in some cases). When the Ligenfelter was on it always went through 1-4 degrees in acceleration. Both stay at 0 at idle.

 

Can you explain this a little more for me?

 

I just seafoamed the car, I'll see if that makes any difference in a few days.

 

Basically I lost all my knock by switching CAIs.

 

That is REALLY odd...

I still have my stock intake in the garage... I could try it.