Well, the truck has had this problem for a while, and I haven't been able to track down a fix for it. 5.3 with the stock cam, Outlaw Air intake, AEM LT's, and a Magnaflow catback. My MAP at idle is around 34-36 kPa, and LTFT's are 6-9% bank 1 and 9-14% bank 2. I have a very noticable whistle / squeal noise that rears it's head when hard on the throttle above say 4000 RPM. I've checked the intake tract up to the throttle body and everything is sealed up tight!

I'm thinking intake manifold gaskets or any ideas? There is a visible buildup of crud around the intake port mating surface of the manifold and heads on both sides. I did notice that the EGR logged value seems to always stay at 14-16%. The noise didn't become noticeable until after the headers / exhaust install. I've included a log to show the idle part throttle sensor readings. No the truck is not yet tuned for the Mods. I want to get this figured out before I tackle fuel and spark tuning.

 

Well, I did some more investigating and found that the rubber vacuum line (from the intake mani) to the A.I.R. solenoid hardline on the fire wall was all but disintegrated! The line literally looked like it was cut in half at the fitting! That got rid of half of the squeal at high % of throttle, still have some left, and I'm thinking intake manifold gaskets? My LTFT's at idle are now -1.6 bank 1 and .9 bank 2. Is it normal to have a + reading on one bank, and a negative reading on the other? Please advise, thanks.