Mystery tech question. What is it? The person who figures this out is a Genius, and I will bow to them and call them a god on this forum.

What: 07 SUV. 11K Miles.

Problem: Having vibration at 1500 RPM, in drive, under light load (eg.on flat highway.).

Resonance (vibration) sounds like enginegrowl or exhaust resonance. Makes engine sound rough. Resonance transfers to body and floorpan.

Diagnosis: Happens at any speed,so not speed related.

Therefore RPM related to drive train, as long as RPM is 1500-1600. Higher or lower RPM, no resonance, and engine is smooth. No codes set.

Most of my cruising is done ataround 1500 RPM range, so the resonance gets very annoying.

Growl goneif rolling with engine at 1500 RPM and in neutral. So guessing problemis in drivetrain behindengine?

Checked another 07, and sound Hz is in same range. 06 Does not do this.

Are all 07s like that? I know they changed the exhaust on the 07's to 3.5" pipes. It sounds terrible. Ifwithin design,still not normal. Makes our 07 a bad driving experience.

Took a 07 H2 Shop Manual and tried to diagnose, but do not understand "orders of vibration", and how to pinpoint source.

Anyone out there with an 07 encounter this?

 

this is something that you can feel through the floor? did you check your transmission undercarriage protection to see if it's hitting the exhaust pipe where it crosses over to go into the muffler? i had a similar vibration at low rpm. i had mashed the cage piece of the stock undercarriage protection and pushed it up to where the exhaust pipe was resting on it. took it off, drove over it to flatten it out, the put it back - vibration gone. may not be your issue, but thought i'd share.

 

Thanks for the info Shortbus. No, everything that I can see from underneath seems tight and straight. The vehicle was never offroaded. The sound is a resonance or growl.

Not a tapping or clanging, or anything hitting metal on metal.

It sounds like it is coming from inside the engine or exhaust. still think something is out of balance or vibrating somehow. Or some kind of pressure resonance in the exhaust.

 

As I read this, this only happens when you are moving. And the vibration stops after you reach a certain RPM while moving.

Check your CV joints and look for grease spatter behind the brake assembly around the A-Frame suspension. If there is no grease thats good, but you still can have a CV joint starting to go.

You could have a Bad Wheel Bearing, Jack the vehicle up just enoughso the wheel is off the ground (Front only) grab the wheel and push and pull if it clunks just a little the wheel bearings might be bad or just not tightened down correctly to the Hub.

Park the Vehicle and chock the wheels so you don't roll and put the Vehicle in neutral and crawl under the vehicle and find the drive shaft, grab it and see if it moves up and down, then put it in park and then go back and turn it till it stops then see if it just turns a little more with a thud sound, could be bad universal joints at the axle pumpkin.

Could have lost a balance weight of one of your wheels.

Check your strut mounts and shock mounts.

Check your pulleys on the serpitine belts.

Check Power steering fluid.

Check lug nuts, see if there loose.

 

I'm going to go out on a limb here for you....

Climb under your truck and see if you have two or 3 metal bands around your fuel tank....

 

Thanks guys!

Ok, I am going to crawl under the vehicle once it is dry outside, and look at all this stuff! I will report back here as soon as this is all done.

 

On an UP-posted(posted above) suggestion of a very cleverHummer guru (Shortbus),I have now crawled under the vehicle and looked at something specific suggested to me.

The crossover exhaust pipe (going from right side to left side collector) is totally pancaked against the UCP (undercarriage protector). GM tried to pancake the exhaust pipe so it would clear, but failed. I had to drop the back of the UCP bolts by1/2" before theexhaust cleared.

The rub point has filed down theUCP at the contact point and exhaust pipe also. If this was left alone, it would have eventually made a hole in the stock exhaust and UCP!

Lots of loose metal rust filings in the area, so it was easy to spot. I could not even slip 1 piece of paper between the two pieces of metal. Could this be the problem?

I easily removed the UCP (3 bolts) by loosening the front skid plate (5 bolts), and will go for a test drive later today.

I do not know if this problem is related, but it is a problem that needs to be fixed. Off to the dealer to bend the exhaust. If it is the solution, it will be a very easy and fast fix.

 

unposted suggestion? damn, glad i could be of absolutely no use to you. good luck getting the exhaust pipe bent, it would be much easier to simply add some washers between the frame and UCP to move the cage down. but what do i know, i'm obviously no help whatsoever.

 

Good Call shortbus, You are a Genius, GURU, The Man. I guess I was completely off base.

 

it just seems like a waste of time to answer people's questions when they don't even read them. nobody knows if this is the problem or not - but i don't see much point in offering suggestions any more.