Pimpinpete

Truck is a 2000 silverado 4wd 5.3 and i have got this awful set of lean codes (Bank 1 and 2 system lean) The truck has a rough idle and started after i changed my knock sensors i.e intake gaskets are good, 02 sensors are good, and i ran some seafoam through the gas so its not the injectors either. This problem is getting expensive, could it be the pcv valve/tubing? the little sensor on top of the intake manifold under the engine cover,with the black plastic tubing and green service cap? or where the egr tube goes into the side of the intake? Please help i need to find the fix asap!!

1FastBrick

iTrader: (17)

How do you know the intake gaskets are good?

Pimpinpete

They are brand new and I torqued them down to spec and used the tightening pattern. They shoud be sealed fine

1FastBrick

iTrader: (17)

Just checking.

You would need to find the vacuum leak allowing the air in.

Have you tried un plugging the MAF to see if runs any better? it will set a light for the MAF but see if it also sets lean codes.

Also look into the FPR Fuel Pressure Regulator and Fuel Pressure. These 2 things can cause hard starts and lean codes as well.

GMCtrk

iTrader: (27)

Sounds like a bad fuel pump. Put pressure gauge on the test port.

Pimpinpete

The fpr was changed about 3 months ago, and this problem started happening right after changing the knock sensors so it leads me to think of the pcv, or any other small systems part like that. I'll check out the fuel pressure though just in case. Fuel pump is about a year and a half old. Maybe it could be the maf I will also give that a shot

Pimpinpete

I changed the fuel filter today an reset the codes and they came back. The filter was pretty bad but I guess it wasn't the problem

1FastBrick

iTrader: (17)

Did you test the actual pressure though?

Pimpinpete

I'm going to do that this evening. Any other suggestions as to what it might be?

Fast355

Intake gasket fell out of place while you were installing the intake and you have a vacuum leak.

Find someone with a smoke tester and get the intake smoke tested.