My truck valve flutters when its at temp. Cold there is no valve noise. plenum is good no vacuum leaks that I can find. opinions on what is wrong?

 

What leads you to believe it is a valve problem? Any misfire codes?

 

No codes truck runs great before reaching temp an makes no noise. When its hot and gets under load is when it flutters. I believe it to be in the.valve train based on the noise. I dont beliebe I have a major vacum leak but is it possible I do? How could I check? I just did a hughes plenum I know its good for sure

 

Spark knock.

Try using some seafoam to clean the combustion chambers, verify you have adequate fuel pressure, try running with the front O2 unplugged, and see if things are any better.

 

Would it not spark knock all the time? Ill try the seafoam an unplugin.o2 an see how it goes. Thanks for your input heyyou

 

Spark knock comes in degrees... depending on the cause. Usually, once you get into closed loop, and hit a certain load/rpm point, it will sound like marbles in a tin can. Plenum is usually the initial culprit.

 

Plenum was bad just had it fixed thats why I assumed valve float. I seafoamed it an put a tank of premium in it and it has pretty much eliminated the spark knock. Im get an 02.sensor code.now and it shakes a bit at low speeeds while in the gas but not when yourre coasting

 

Think I would try running some seafoam thru the vacuum hose for the brake booster. (into the intake.) Then take it out and drive it hard for a few minutes, and see what happens.

 

Ill give it a shot