when my car is cold, itll read knock all over the power band and at pretty much any load, vacuum, and rpm, but after about 6 minutes or so, it reads nothing. where in the tune is this possibly coming from if anywhere? anything i can do to fix it?

 

Well, has it done this for a long time? When did it start? Any codes thrown? Is it stopping the retard when the car goes into closed loop?

 

well I had the car tuned on august 20th i believe, I dont think there was any knock present when it was tuned but then again, it was warm by the time i got to the dyno, i noticed it a few days later when i logged it on my way to work. It is set to not go into closed loop ever because of the overlap from my cam. Its probably got maybe 300 miles on it since the tune and it seems strong, i cant hear any of the marble sounds or anything that they normally associate with knock and the most retard it pulls is 5 degrees, usually its pulling .4-2

 

I think the PCM pulls 3* of timing out as it is warming up. Are your timing amounts different when driving the car cold vs. hot? If that is the cause, then you need to possibly pull out a little bit of timing all throughout the table. As for not hearing the car knock, from what I understand, the knock sensor will hear it and pull the timing out before you will be able to notice. I would think it would be true knock though because it goes away as the car gets warmer. Hope this helps.

 

thanks for your help, also this is a lt4 knock sensor or knock module i believe. the car had something lt4/knock related when I bought it. ill try to put up some datalogs when I get home from work tonight

 

It is most likely piston slap. Pistons are loose in the cylinder until they warm up and the block warms up. Mine also shows knock retard when its cold but gets 0 knock retard when warm. Every LT1 I've ever ridden in gets piston slap. Not a big deal as long as your easy on the engine till it warms up.

 

Yes be easy till it warms up.

 

* Its even more prevalant on a LS motor.