Well, I got a weird one for you guys. I am helping a buddy tune his LS motor. It is an LS3 block but we are using the early LS1 style PCM with a 1X cam position sensor and 24X crank trigger wheel. We are using Tuner Cat OBD II software for tuning and HP Tuners to data log. The car uses the original LS1 knock sensors.

The car starts and runs like a champ everywhere but WOT. As soon as you get to WOT the advance drops right to zero. This does NOT appear to be due to knock retard. We have turned off knock retard everywhere we can find it and HP Tuners does NOT report knock retard. It does show the timing going to zero and that's exactly how the car acts, like it has no timing. Goes flat as hell and stops pulling (we are testing on a chassis dyno with load applied to the rollers).

Any ideas?

Richard

ps: just for clarity, the we are picking up cam position at the front with an LS2 style sensor. I am quite sure the sensors are all working properly as there are no related error codes and the motor runs GREAT except at WOT.