Do I need a tune?
I don't have anything "enhanced" running in my very similar 5.3 liter engine and 4L60E transmission. I have kept the low octane fuel table and the only thing that I have tinkered with very much is the idle speed. I started at 800 RPM - too fast. Then went to 550 - slightly too slow. A 650 RPM has been just right. Currently, my Power Enrichment is factory stock. I have not advanced any timing though I suppose I could gain some performance there.
The only thing I noticed in my engine was that my Long Term Fuel Trims were being maxed out at a plus 25% fuel added. Short Term Fuel Trims were normal-ish at around 5%. My air filter and intake system was causing too much chaotic air at the MAF and this was confusing the MAF. With the air filter mounted straight onto the throttle body . . . no problems. I also run headers and I think the PCM has readily adapted to that change without any tuning required.
Rick





