I have my truck tuned with EFI live. The tune is great and truck runs strong for 150 to 100 miles. then the truck gets really sluggish and loses power. I can take the negative battery cable off and let it rest itself and it will run strong again for the 150 to 200 miles and starts to act up again. Any thoughts on what it might be. Someone told me the truck has to find its idle and when it dose it changes something. is there something that can be changed in the tune to correct this? Also when it changed itself after the mileage the idle is 200rpms higher. any thoughts or help on what to look at would be great. I don't have a way to down load the tune my tuner has it.

 

You might have bad oxygen sensors and truck learns to add fuel then when you unplug battery it resets fuel trims.

 

fuel trims are not dialed in.

 

Okay, it also smells of gas while idling when it goes into crap mod. I put 2 new O2's in a few months ago but I'll change them again to see what happens,I only have the two upstream sensors with no cats. while the tuner was working on it the AFR was 12. something. how can you tune for after it finds its idle or should it change from when its rest and the 200 miles.

 

okay, took truck back to tuner and he said it was showing a knock and pulling spark. he made some adjustments after riding around a little while and it seemed to have fixed it. Now if I nail it from a stop it dose it again, starts acting like it loads up and did it this am while trying to pass a slow as car, also on a cold morning start it dose it again until warm and neg cable is taken off for a few minutes. So could I have more problems that spark adjustments? my valve train is making a little noise but can it set off a knock sensor? or could a bad coil that under load flips out and screws everything else up?