Timing Problem, Need Help!

Im posting this for a friend who doesn't have any internet. Hes having some issues with his car overheating due to the timing. Hes got a Greddy t-66 turbo kit on it as well as 3in exhaust and Unorthodox cam gears. His Autronics engine management is set 15 degrees at idle however, when using the timing light his crank pulley doesen't match up to that all the time. It'll show 15 degrees then all of a sudden the mark will "disappear" then come back to 15. It seems to do this while driving, causing his engine temps to skyrocket. No one has been able to diagnose this problem he is having. He thinks it could possibly be something messed up in his wiring harness. If anyone can help on here that would be great. Thanks!