JordanH

iTrader: (16)

The truck is tuned through HP tuners... Here's the problem, for some reason after putting gas in the truck, it will act like it was never tuned? The A/F will stay at 14.7 no matter what kind of boost it sees? This will go on for five or ten minutes of driving around and then it goes back to normal.... Except for the fuel tables will be off and the HP/TQ will be down?! It does this everytime I put fuel in it!

So just to be clear... After tuning, the truck is strong and running good, until I put fuel in it, then it acts like it was never tuned, for about five or ten minutes, then it goes back to normal, but loses power?!!

Any ideas?

George C....

are you fueling the truck with it running? if so thats will do that

JordanH

iTrader: (16)

No it's off everytime.... And it doesn't matter if I put one gallon or 20? It's like the truck alters it's fuel tables after the tune, when I put fuel in it?

George C....

has to do with you cracking the seal for the evap system, check to make sure you dont have any pinched lines as this makes alot of sense

as more you drive more vacuum is created with line being pinched. once cap is opened it allows the lines to become unpinched. if this is correct then youll need a new tune once you fix your issues

JordanH

iTrader: (16)

I'm gonna go take the gas cap off, and see if it does it without putting any fuel in it...

JordanH

iTrader: (16)

What lines? Evap lines?

JordanH

iTrader: (16)

Well, it doesn't do it when I take the gas cap off.... Only when I put fuel in..

George C....

that makes no damn sense

unless truck has a ethanol sense and its goofy

JordanH

iTrader: (16)

Lol! I know! My tuner has never seen or heard of it either? There are no codes, so I have no clue....

JordanH

iTrader: (16)

Thanks for the input George! Have you tuned many 07-08 GM trucks, with the factory computer?