Hey guys,

So my truck is throwing these codes
P0171 - Fuel Trim System Lean Bank 1, is what it is saying for this code


P0300 - Random/Multiple Cylinder Misfire Detected


Any help with what this may be, im kinda leaning towards the MAF, also how do you get rid of a truck running lean,

Truck is an 02 GMC, intake, exhaust, and tune, thanks

 

i hope someone answeres this. i have the same problem. the misfire has got me leaning to a fuel filter or pressure regulator.

bump for ya!

 

thanks its needed

 

Try unhooking your MAF for a day or so and clear your codes, the computer will use it's own tables for the amount of fuel to use at each RPM. I would probably lean more towards an injector if you keep getting lean on just the one side.

 

I just been having this same problem. I checked the codes today . PO171 and PO174 lean banks. I just changed the fuel pressure regulator. Problem is the same a little better but no much . What else could it be?

 

Intake gaskets (o-ring seals) are leaking - cold weather makes 'em leak worse. VERY common issue . . .

 

The truck runs fine on the freeway. At idle it does stumble a bit and when I drive it at low in town driving speeds it falls on it face when I go to give it a little gas. If i jump on it from a dead stop it will cut out and back fire. Like it loads up then it takes off then stumbles again. WTF. If i ease into the gas it runs fine? So i have to ***** foot my truck to drive it and it is driving me nuts. I"m gonna do an oil change, re-place fuel filter, clean mass air, clean throttle body today. It needs to be done anyway but I have to rule a couple thins out first. I will also check for any vaccum leaks too.

 

To the original poster, try swapping your 02 sensor from the left bank to the right and see if the code follows. If so bad 02.

 

I'm with you. Intake gaskets could be leaking, fuel pressure low, or lazy o2 sensor only showing 100mv with cause ECM to continue to add fuel and get Bank1 so loaded it will misfire on 1,3,5,7.

 

Who tuned it?