I have a few questions about a tune that I recently got. I will leave out the tuner(reputable) so this doesn't turn into a flame thread.

I have an 03 SSS AWD. The ONLY thing done is Efans and the tune. I asked for a pretty standard 93 octane tune, and I believe thats what I got. My problem is with the mileage. It went down by 2mpg.
BTW, shakinLM7 has offered to do some logging for me, which is greatly appreciated.

When I had my other truck tuned (02 5.3 Z71), by a different tuner, I got a performance gain, and 2-3mpg gain.

WTF

Can someone explain how fuel mileage is optimized in the tune?

 

drive it and let it relearn fuel trims. and keep your foot out of it. that is usually my problem.

 

are you running a 165 t-stat? That was the biggest gas sucker I had before I got tuned for it.

 

Stock Tstat, not getting on it, trying for the mileage right now. I would mind if I was the cause of the mileage drop

 

Timing and converter lockup.