: P0171, P0174 After replaced Plenum

06-08-09, 11:13 PM
Hello, I have been searching the site today, and have found a lot of info. What I am curious about is how tight should the clamp on the intake plenum be. The plenum has been replaced only a couple months ago and I am getting the codes of P0171, and P0174 on and off. I opened up the hood and noticed the clamp on the plenum was rather loose. Could this be causing a small leak, and be the reason for the trouble codes to set?
Thank You

06-09-09, 09:26 AM
The clamp should be tight - just like a hose clamp. Pull the beauty cover, start the car, and use a small shot of choke cleaner or starter fluid at the plenum joint and the overpressure valve in the other end of the manifold. Any idle speed change is a vacuum leak, which is what's setting the codes.