High frequency whistle/squeal sound??

I've been hearing a high pitch sound recently and need some help on where to start looking for the problem. It usually happens in 2nd, 3rd, and 4th gear when accelerating. It almost seems like it's dependent on throttle pressure. If I back off the skinny pedal a tiny bit it goes away. If I go back to about the same position in the pedal's travel relative to the floor it comes back. If I hold steady pressure on the pedal and accelerate through it, the sound stops after a few seconds. It doesn't seem to be dependent on RPM because if I accelerate through the sound then release the pedal and let the RPM drop through that range again there's no sound, and I don't hear it when downshifting. I also feel like it isn't related to the brakes because the sound isn't a constant squealing. I have a '08, with the 6 speed, 3.21s, and about 33k on the clock. It has about 3 inches of lift with 33x12.5 Interco MTs on 17" wheels. I'm actually switching out my lift soon so it sits a litte bit lower. I'm just trying to gather some info on what to look for since the Jeep will be on jack stands with the wheels off anyway.

Edit: Also, it seems to be coming from the rear, but it's hard to tell.

do you have a CAI?

Nope, stock intake, stock exhaust and all that. I considered the chance that it might be a vacuum leak somewhere, but wouldn't that throw a code? I don't have anything showing up. I've done the key thing to check codes a few times and just get the"-----" thing then it says "done".

Check your intake duct to be sure it is all connected.


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Canvas JK said:

Check your intake duct to be sure it is all connected.


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x2 check your intake and the hose where t connects to the motor. It almost sounds like the CAI whine I get from mine when I accelerate.

Seems like a good place to start. Thanks guys! Now that everyone has me thinking about it, maybe it's just loose and the sound is happening when the throttle body opens up to a certain amount. Would that make sense? I'll check it out later today. I've been at work all morning thinking about it lol

Your comment on it sounds like it's coming from the back might be worth a look. While it's on the jacks give the exhaust system a look. A pinhole in the can or a slightly loose clamp can drive you crazy. Good hunting.:twocents:

when was the last time you cleaned your TB? easy to remove and clean.

jeeeep said:

when was the last time you cleaned your TB? easy to remove and clean.

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I actually did it not too long ago. Probably sometime during late summer. I didn't even consider that as a possible culprit but maybe I didn't tighten everything up 100%. I figured anything like that would throw a code.

JeepDrum said:

I actually did it not too long ago. Probably sometime during late summer. I didn't even consider that as a possible culprit but maybe I didn't tighten everything up 100%. I figured anything like that would throw a code.

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Nope I dont think so.

As long as the fuel to air mixture ratio isnt jacked up and the pressure is steady you wont have a code.

But it might just be loose enough or there might be a pinhole vaccuum/exhaust leak somewhere enough to drive you nuts.

good luck!

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