2002 Gmc Misfire

[kristenc]

I have a 2002 GMC sierra 1500 5.3 and it runs like crap. The check engine light blinks and the codes are PO174B-Fuel trim lean bank 2, PO300B- misfire detected, PO151B-HO25 circut low voltage B251. I just replaced the intake manifold gaskets and it runs the same. I cant go over 70mph and thats with the rpms between 400 and 500. We are having a hard time figuring out the problem. It has a new fuel pump, fuel filter, new plugs and wires. Any advice?

[Chanks7]

I have a 2002 GMC sierra 1500 5.3 and it runs like crap. The check engine light blinks and the codes are PO174B-Fuel trim lean bank 2, PO300B- misfire detected, PO151B-HO25 circut low voltage B251. I just replaced the intake manifold gaskets and it runs the same. I cant go over 70mph and thats with the rpms between 400 and 500. We are having a hard time figuring out the problem. It has a new fuel pump, fuel filter, new plugs and wires. Any advice?

 

Whats your fuel pressure doing?

[kristenc]

Fuel pressure is good with key on and off

[Chanks7]

Try unplugging both upstream oxygen sensors (the ones closest to the exhaust manifolds) and then restarting vehicle and if it runs better replace the bank 2 oxygen sensor, also when you unlpug them disconnect battery for 5 minutes first to reset PCM learned values. If it still runs poor remove bank 2 oxygen sensor and drive to test for a plugged converter.....

[KRT]

Sounds like you have a vacuum leak? Maybe, maybe not. I would either smoke the system or better yet spray carb cleaner on and around the intake and see if the idle picks up.

[kristenc]

Sounds like you have a vacuum leak? Maybe, maybe not. I would either smoke the system or better yet spray carb cleaner on and around the intake and see if the idle picks up.

 

Tried spraying starting fluid to see if it would die and it didnt but I will try doing this now. Thank you so much for all your help and any more advice is greatly appreciated.