98 k2500 bad fuel economy no power

[randomguy]

Closed loop isn't that significant for mileage and rear O2s have no impact on performance or fueling.

It should still throw a code.

 

[Supercharged111]

What do you mean by this?

I asume he's saying he can't do a brake stand. Don't forget guys a 4L80 really makes the firdt 2 gears a lot more gutless through 1st and 2nd.

 

[Roger Stephenson]

I would suggest disconnecting the battery to clear out the computer for a first step. I would also set the timing correctly and move forward from there. I don't know if either of these will help but at least you will know that you are on a level playing field to begin with plus it is no cost other than time & effort.

 

[turbotrix2004]

I would suggest disconnecting the battery to clear out the computer for a first step. I would also set the timing correctly and move forward from there. I don't know if either of these will help but at least you will know that you are on a level playing field to begin with plus it is no cost other than time & effort.

Yeah I’ve done checked it 3 times. It’s very frustrating.
Is there a way to check if the pcm is bad?? I have no cats, no simulators, no codes