Well this on an 04 QC 4x4 with the 5.7. Driving down the highway today at about 65 I got this wierd high pitched whistle sound. It only happened right at a certain RPM or speed, which was right around 65mph. Im pretty sure it is engine related because if I would back out of it get into it the sound would go away. It happened probably 5 or 6 times out of a 300 mile trip. I know its not a lot of info to go off of I am just wondering of anyone else has had any symptoms or problems close to this. Thanks Ben

 

That is interesting because I have the same symptom on an 07 Aspen 5.7. Under warranty, going to the dealer Wednesday. The only difference is mine happens at about 750-80. To me, it sounds like a whining fuel pump, but I will take my mechanic at the dealer out so he can hear it and let him decide. Annoys the hell out of me.

 

i bet dollars to donuts it's the intake....

 

You didnt happen to have a Disney movie in the DVD player at the time did you?

 

Its either intake or a loose vacuum line.

 

Intake as in leaking gasket? Could that cause it to occur only at a certain speed? Little more info from my situation.
Only occurs from about 75-85 and only during acceleration. Accelerating at any other speed, little or a lot, no noise.

If I am doing 065 or 90 and accelerate, no noise.
Driving 80 and coasting, no noise.
Driving 80 and accelerating, loudness is proportional to how much acceleration.
Driving 80 and just tap the pedal I get noise. Foot off pedal, no noise.
Not related to wheel speed (only under acceleration)
Appears to come from back of car, but 100% certain.

This was my reasoning for fuel pump. I am not an expert, justwanting to learnhow an intake or leaking vacuum line could cause this.

Thanks, don't mean to hi-jack, I am thinking we have the same issue.

 

No its fine. If we can solve more than one persons problem with same thing, awesome. Yeah yours sounds like it could be the same thing. If you setthe cruise right at the sright speed it will just sit there and do it for however long its set as long as you dont have to pull a hill or anything. To me its directly related to engine speed or RPM. I thought too that it might be vacuum leak or soemthing because it seemed to kick the cruise off. One time the cruise just stopped holding, but arent these engines Drive By wire which in that case it would all be electronic. I used the cruise after that and it worked fine and still made the noise.


When you say intake leaking, do you mean the intake plenum or intake track before the throttle body?

 

REALLY high pitched? I just had the heater vent door fixed on mine and now I'm getting that. Got a wicked silicone smell just figured when they resealed the ductwork they didn't seal back correctly or an air leak...windowish??

 

I get the same thing at around 110km/hr...

 

I dont think it could be an air leak or anything because it is too steady. Its a steady pitch that changes or goes away with engine RPM.