2001 4.2L v6 running lean on bank 1
 

Hello all,
My truck recently threw an engine light and the code was for running lean on bank 1 and speed sensor on front driver side missing. I am more concerned about the lean right now. At first I could not notice a difference but I used sea foam and cleaned out the engine and injectors just to be sure. (Smoked like no other!) But there is still something not right, it feels like I have turbo lag when I first step on the gas and I can hear what sounds like air getting into the engine when I accelerate. Is this just a vacuum leak or could it be something else. I am all out of ideas on this one. Thanks in advance for the help.

Brad

First off, I'd never put seafoam in my truck in a million years. A lot of people around here feel the same.

Sorry, I don't have an answer to your issue. Someone else will chime in, hopefully.

Take a close look at the valve covers, I had the same issue when a cable from the cruise control had rubbed a hole in one of the valve covers causing a lean bank.

If you have a plastic intake manifold, it could need gaskets and isolator bolts. This is a common cause of running lean.

1. Check PCV hose plumbing. Very common.

2. Leaky intake manifold gaskets and isolator bolts very common on that engine.

I had the same lean in bank one in my truck. My shop teacher had me run a water hose on the intake manifold with the truck running to see if it would suck in water. it did so we changed out the gasket and isolator bolts and she runs great.

I just dealt with this same issue on my 5.4L motor, it was throwing error code P0171, lean on bank 1. The problem turned out to be a vacuum leak in the PVC system, due to a crack in the rubber elbow fitting where the PVC tube attaches to the back of the intake manifold.