5.3 Lean Codes - Help

red_chaser · January 19, 2012

Hello. I'm a newbe here.

I first had a check engine light for some knock sensors. I went and replaced those, took off the intake manifold, replaced the seals, cleaned my injectors, and put everything back. Torqued down the manifold screws to 44 in-lbs then 89 in-lbs, put all the hoses back, cleaned the throttle body, and re-installed the EGR hose.

The Knock sensor codes cleared and about a day later got new codes, P0171 & P0174. Did some research and it could be a vacuum leak. So I went back make sure everything was on right with some carburetor cleaner and found that the EGR hose had a leak where it plugs into the manifold. I bought a new o-ring gasket and re-installed it, drove it around for a while and the fault cleared.

The truck was running nice. Even a rattling nose it had upon hard acceleration went away. Tons of power and acceleration. Two days later the same P0171 & P0174 codes came back. I am at a dead end. Could be the MAF, O2 sensors, injectors, ect, but I don't think that is likely because the truck was running without any codes until I messed with the intake manifold.

I can still hear a leak where the EGR hose plugs into the manifold. I am thinking of using RTV around that damn hose.

Any advise. Sorry for the long post, I needed to vent.

Silverado, 2001, 5.3, 4WD

Stephenspann27 · January 19, 2012

This story sounds kinda familiar. I ruined my knock sensors by washing my engine. Before this, I had an engine "rattle" under hard acceleration just as you mentioned. While my knock sensors were "broken" the rattle went away. It was then that I realized that the rattle was the engine pinging. While the knock sensors were "broken' the PCM was running a "safe" ignition map and the pinging was gone. I removed the intake, replaced the the knock senors put it all back together. The knock sensor error went away, and the pinging came back. I've been trying to get rid of it ever since.

If you attach a scan tool to your truck and watch your bank values you want them to be a close to zero as possible. If they negative or postive more than a certain value (I think its 24) then a rich or lean code is thrown. (you might already know this).