Crazy PT knock

[white1]

Tuning a Grand Cherokee SRT with a cam motion custom 218/224 cam
I'm getting some crazy knock at very light throttle (audible knock) but if you give it a little throttle it goes away. I've never run into this issue before and I'm lost as to what could cause light throttle knock.

The Jeep originally came to my shop with a Comp HRT stg 2 cam. We scheduled a tune appointment and before he come for tuning, it sheared the dowel pin. Took out all the exhaust valves and broke a couple of pistons. Installed 4032 forged drop in pistons and put a new cam. Engine was pulled, torn down, hot tanked, new cam bearings, crank was turned, new main and rod bearings, and all exhaust valves replaced.

Cranks, idles, runs, and drives fine (as long as you DRIVE it) but at very low throttle input the knock sensors go crazy, the audible knock is obvious, but with enough throttle to make it down shift, it clears up. WOT pulls are pretty clean (it's been parked a while, I question the quality of gas, but I'll get to that when I get this figured out) Poor gas quality might be my issue, but it seems I'd see knock in higher load areas if that were the case vs just very light throttle.

jeep log.hpl
Jeep Grand cherkee SRT CM 218_224.hpt

[N2speed]

Need to adjust Knock sensors with forged pistons as they can be a bit noisy especially when engine is cold.

[white1]

It is the 4032 vs 2618 but I probably still need to adjust them. I just wasn't expecting that much audible knock at low throttle, that goes away with a little more throttle. I was leaning to stale fuel (which I do believe is A factor, just not THE factor)
Especially the amount of knock the PCM is seeing, but its loud. With the windows up, it's very noticeable

[white1]

You might need to pull some timing out of the part throttle lockpin table where it's knocking.

I'm sure I need to, but wasn't expecting that much knock. Especially at part throttle. Gonna fill up with some fresh fuel in a bit and give it another go

[evildodge]

Looks like its going a little lean in 1300 1600 area even though 02's are picking it up yet, double check with wide band

[GeForce1986]

its the fuel . pot some good fuel on it and try again also take some timing from the part tp table as i did this in my 426 and it did work and i used to have same of your issue from idle to low throttle

[white1]

Thanks. I topped it off with some fresh fuel and it got much better. I also pulled a little timing in that area and its just about all better now.

Thanks everyone for the advice

[luciddeath]

Timing is really low.. probably just cheap fuel. it shouldn't need to be negative timing when you get on it

[white1]

Fresh fuel and a little trans tuning seemed to clear it all up. Thanks