Timing going NEGATIVE randomly...help please

[exploder]

We just put a 6.2 motor in an employees truck the other day. We have been road tuning it here and there and the driveability while moving is pretty good, however after coming back down to an idle the car will go rich for a moment or two then go full lean then it will drop to negative timing and go rich again. It does this multiple times. I caught it in the log file at frame number 4542. I also saw a few places where it went negative while driving as well and once while WOT frames number 2988, 3608, 4406. The truck also goes full lean at first startup and will hold there unless you give it a little gas. Probably unrelated, but I need to get that tuned out as well. Any help on any of these problems would be appreciated.

[pullincrazy88]

it might have something to do with the VVT settings if you have tried to modify the tune at all. i was actually just reading in Hot Rod mag. i believe it was about the new Variable Valve Terrain on the 6.2. advancing and retarding the cam could make you go lean and rich with how much over lap you are seeing (or not seeing) and could also cause KR i would think. but also could be completely unrelated at all... just a thought to throw out there, but don't hold me to anything.

[exploder]

We disabled all of the VVt stuff and use a conventional LS2 timng gear.

[odd boy]

is the crank pulley okay? I mean it shouldn't vibrate. Sometimes, aftermarket ones aren't okay due to installation problems.

[exploder]

Checked the crank for endplay and it has none. It spins freely and does not wobble.

[odd boy]

I need better loging that shows the fuel triming as well as the fuel status and the HO2S