I've been getting a ton of knock retard on lately. But only in the upper rpm ranges (5500+). I'm N/A and my only internal mods are a cam and springs.

I've checked the obvious stuff first, like loose rockers, exhaust leaks, things rattling. I had a leak by the EGR valve, but I fixed that, and the problem still persists. Are there any other mechanical things it could be. I've been all over with a stethescope and I don't hear any ticking, rattling, tapping etc. I think I have a small leak where the y-pipe bolts to the rear pipe, but I don't think that could cause the much trouble.

The reason I don't think it's the tune is because when I look at my logs, I add the advance to the KR and that # corresponds to #'s found on stock timing tables. I'll see as much as 8-10* KR, then the truck sputters and backfires.

I want to get this issue worked out before I throw the turbo on.

Oh yeah, my fuel pressure is rock solid at 60psi. I know that doesn't tell all, but its all I have to go off of.

 

ASP underdrive pulleys are known culprits.

 

Run a couple cans of Seafoam through it, you may have some carbon build-up on the pistons.
Philip S.

 

Agreed. I get pinging if I go 30+K without a top engine cleaning. Pinging goes away afterwards.

 

There's no audible pinging, just KR and then it has a **** fit.

I just ran some Berryman's engine cleaner through it about 2 weeks ago. It didn't smoke, but I did notice some better throttle response.

No underdrive pulleys, and did re-check the crank pulley bolt recently.

 

99-00 PCMs are prone to false KR, especially with an aftermarket cam. 02 PCM cures that, if you don't already have one.

 

hows the 02s look above 5500?

 

They're fine, no signs of leaning out. I don't have the #'s with me now, but I'll get them tonight.

I do have the 2000 PCM and the good 'ol hotcam. It never had this problem before, but it's as if it all started when I got all torque management removed.

 

Loose exhaust components can and will cause false knock retard, that is if it is loud enough.

 

maybe the TM was pullin that timing before and now that its gone its just showing up as KR
another thing you could check is the AFR adder to the timing table
I 0'd mine out so I would have more control over the timing
It could be trying to throw more timing at it and setting off knock at the same time