New 2011 5.3 Silverado, 510 miles. Commanded AFR of 10.8 and as little as about 21* of timing in some frames! I don't have a wide band on it but if commaned is actual then GM has tuned this engine awfully rich. My truck could use a tune!

 

Yep, and the 6.2's are like that too. They've detuned the **** out of them.

 

Yep, I'm sure the 6.2s are about detuned about the same. For GM to give these trucks a 100K mile warranty I suppose they have to be very conservative.

Gut my third cat that seems to me almost redundant, give it a good 93 octane tune and I might pick up a few horses.

 

As redundant as it seems initially, these new trucks run so ******* rich when in PE, that I could see them NEEDING the 3rd cat....

 

Good point! And even when not in PE notice the 14.37 commanded at idle/part throttle vs. 14.68 normally.

 

What is the Ethanol % displayed in the log?

14.37 should be about 7%.

 

Is there a PID for Ethanol %? I'm not finding it if there is.

The pump that I bought gas says up to 10% Ethanol I believe. However my Corvette always shows a commanded 14.68. I did buy 89 octane and always 93 with my Corvette. Maybe a difference???

 

Normally I have seen they are a little leaner than the commanded. The stock maf calibration is not dead nuts accurate.

 

Pretty sure that 7% should be more like 14.27 and is your corvette e-85? If not it will command the 0% ethanol content and your fueling will have that E?% error from the start.

 

I use 93 octane in the Corvette from the same Chevron station I bought the 89 for the truck.

I'm going to try 93 in the truck and see if anything changes.