69gto96z

I have a scanner/code reader like they use at autozone. One of the things it shows when you are viewing the data is "IGN ADV." My buddys bolt on car with a pcm4less tune runs about +23.0 to +28.0, my car runs around -23.0 to -28.0. This means that my timing is retarted that many degrees correct? Is there a reason for this? The car is a cam only cc306 with a madz28 tune and bolt ons. Could it be in the tune, or could i have a problem somewhere?

shoebox

It's just the way each scanner displays. Yours is the same as your buddy's. There is nothing wrong.

If the scanner says "advance", the numbers will be positive.

If the scanner says "timing" or such, the numbers will be negative.

After all, timing is negative (advanced) from zero. It would not run with retarded timing.

Injuneer

Your question is actually answered in my online guide to scanning the LT1, under "spark timing":

http://members.aol.com/InjuneerZZ/ScanMast.htm

69gto96z

Thanks, will check out that link.