Vibration at Low RPM's

I've been noticing a vibration... only at low revs when the engine is under some load (but not enough to make it downshift). Vibration can be felt mostly through the accelerator. If I give it enough gas to force a downshift, the revs jump and the vibration goes away. Let it shift back to higher, lug the engine, and the vibration comes back. Anybody else experience this? Also, there is a slight audible sound, low frequency "growling" when it is occurring.

Thanks,
Dave

The growling could be a bad front wheel bearing/hub. You could get the front end off the ground, roll the front wheels to see how they feel & sound. I'd then check the level of the front differential oil. Another possiblility is the front pass side inner half shaft bearing & carrier. There's a bearing housing bolted to the oil pan on the pass (left) side that the inner CV joint couples to. The housing is sealed and just packed with grease.:disappoin I've seen a couple of failure reports on this now on mid/hi mileage 2002 and 2003's. The most obvious symptom is MAJOR play on the inside of the pass side half shaft.

Joel

I've been noticing a vibration... only at low revs when the engine is under some load (but not enough to make it downshift). Vibration can be felt mostly through the accelerator. If I give it enough gas to force a downshift, the revs jump and the vibration goes away. Let it shift back to higher, lug the engine, and the vibration comes back. Anybody else experience this? Also, there is a slight audible sound, low frequency "growling" when it is occurring.

Thanks,
Dave
Is this car speed sensitive or engine rpm/load sensitive, there are issues with a low resonance growl in these trucks at 55-62 under lite load.

I've been noticing a vibration... only at low revs when the engine is under some load (but not enough to make it downshift). Vibration can be felt mostly through the accelerator. If I give it enough gas to force a downshift, the revs jump and the vibration goes away. Let it shift back to higher, lug the engine, and the vibration comes back. Anybody else experience this? Also, there is a slight audible sound, low frequency "growling" when it is occurring.

Thanks,
Dave
Does this vibration somtimes come at idle, also associated with a chirping noise that dosent go away until you drive a bit?

Very anxious to hear reply.
Josh

Thanks everyone for replies...

Wheel bearing/hub assembly: I replaced the left front assembly a month or so ago. That was a different noise, a higher frequency "whine" that you could hear and feel in the steering wheel. It was dependent on steering wheel position, issue showed on right hand turns (which loaded the left front tire). Replaced hub - issue fixed.

Half shafts/CV joints: Inspected driver side when I replaced the hub, it was fine. I'll have to check for play in left front. You've heard of cases where low diff fluid caused vibrations?

Speed sensitivity: doesn't seem to be related to speed, but to RPM's. I feel it at low revs (around 2000 RPM) in all the gears. Most prominent at around 50-55 MPH in 4th gear. Not related to torque convertor lockup, tapping brakes does not get rid of noise. Your description "low resonance growl in these trucks at 55-62 under lite load" is pretty good description... but it occurs not just at these speeds, but at any low RPM, lightly loaded condition.

Noise at idle: Doesn't go away after driving and doesn't appear at idle, only when moving. And there is no chirping noise, just low frequency vibration.

Don't know the year here but there was a tsb for 2003-2003 TB for this conditon ( maybe) where the rear springs were replaced to dampen this drive train resonance. Had it done to mine, about a 50% improvement, also make sure the exhaust isn't grounding against the frame or floor somewhere. Also driveshaft balance and mfg tolerance issues were a problem too, but from here I cannot tell what the problem is of course.

I can't seem to find a TSB on rear springs. I did find TSB 3516:

"VIBRATION FELT AND HEARD AT LOW RPM DURING PARKING LOT MANEUVERS."

And it does occur in first gear... but it also occurs in every other gear. Anybody know of a source for full TSB's (other than subscribing to one of the sites)?

A dealer can get you the TSB's if they apply to your truck, still no year mentioned! They may charge you a copying fee. Ok, I see in the profile, I don't think the springs TSB applies to your newer truck

Sorry about that... yes, 2004. Thanks for the help, I'll post when I figure out what is going on with it...