Curious if my tune is correct

[Skylardog123]

So, I have a 99 silverado 1500 with a 5.3, a local guy near me has hp tuners and tunes alot of drag cars he builds and alot of local peoples pickups near me, I had him tune mine hoping to get more fuel milage than power. But fuel mileage didnt change not one bit and power was increased very slightly. I posted in the forums that my long term fuel trims read 0% all the time and was assuming that's because of the tune, but was quickly informed that my long term fuel trims shouldnt be tuned out and should still be reading, is this correct, should I go back to the stock tune or what?

[1970ss8.1]

Post your tune so we can see what has been done to it.

[5FDP]

Good luck gaining fuel mileage with a tune. If you got 1mpg avg better I'd be surprised.

[Skylardog123]

Post your tune so we can see what has been done to it.

It's a custom tune on a 99 silverado, have no way of posting it

[1970ss8.1]

Then there?s not much we can tell you.

[cobaltssoverbooster]

you can get gas mileage but it takes a lot of work. as 5F stated, its typically a low increase. usually you have to disable the closed loop fuel control so you can command a lean afr on the open loop afr table when in the cruising regions. This means your ltft and stft stop working. there is also a bunch of transmission settings for autos and tweaking of ignition. Takes a lot of running time to verify the changes are making progress.
manual transmissions get better mileage since they dont have the energy waste that a converter has.
as for power, well a bone stock motor only picks up between 15 and 30 hp. it rarely enough to feel any major gains on ye old butt dyno.

without a tune file as mentioned, we cant verify any of the settings to give you a answer that pertains to your specific application.
also a recording (log file) to go with helps a ton in terms of analysis and problem solving.