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Old 10-06-2012, 07:44 AM   #85
strych9
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Drives: Subaru, HD Road Glide Special
Join Date: Apr 2012
Location: Omaha, NE
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Quote:
Originally Posted by PQ View Post
Very interesting. Thanks for going the distance and checking this out PQ.

All I can figure is that they either cleared the memory with test equipment during their testing, or as NFERNOSS said, a different fuse. Or, something altogether different fixed the issue.

The PIP does mention fuse #20. I suspect that this circuit may hold some parasitic voltage for a short period of time, so that's why GM calls to remove this fuse for the ECM reset. That's why I specifically stated to wait 45 minutes before testing, so any parasitic voltage could bleed off before testing. Good stuff.

I would have thought that GM would have revised the ECM logic to start at maximum timing advance with every new start of the engine, then back off and hold back advance as dictated by the knock sensors until the engine is restarted again. This is the logic that most cars use.

GM engineers, please speak up.
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