sbrown99TA

Hi all, Just wondering if any of you might have an idea about this. My friend has a 2001 5.3 Silverado with an ATI on, and we're seeing spark knock. Here is the wierd part. We logged his spark advance, and it's 4-5 degrees more than what we are telling it in edit under WOT. We logged advance in EFI live using the spark map table (RPM vs. gms/cyl). Our file that's in the truck says between 12 and 15 degrees in the .92gms/cyl + cells, but we're seeing 17-20 with 4 degrees of retard. Any ideas? Is there something that's making it keep that much advance?

etc

think i saw this here. try zeroing the fuel ratio vs rpm modifier in edit engine ign. tab. apparently it uses this to add timing when conditions warrant it. someone correct me if i'm wrong. in my edit manual this button isn't shown in in the window. i believe i read that this should be zeroed for most performance applications particularely if you are pushing the limit with your timing. it doesn't make much sense to me that the pcm would arbitrarily add timing then pull it out with knock retard. but then again alot of this doesn't make sense to me yet.

deezel

I'd also say check the Fuel Ratio (EQ Ratio) vs. RPM spark advance modifier table. I seem to recall someone mentioning that this table was all zeros until around 2001-2002 when GM started using it...