I have 2007 H3, 100K. For about a week now, when I get to around 2000 RPM and I have the foot on the gas pedal, the car starts to vibrate until I either take the foot of the gas, or I get to over 45-50 miles/hour.
I don't want to go "blind" and be husstled by the dealer or other machanics... Can anyone help?

 

Do you have a flashing check engine light? Check for air leaks in the intake as well as the crank case vent tube coming off the back of the cylinder head. Does it go away with mid-octane gas? Are you using "tier 1" gas? Clean the MAF sensor and throttle body just to eliminate those from the mix and how is the condition of the battery/connectors? Voltage spikes/losses can really do a number on the computer.

 

RSC, you get my vote for The hummer enthusiasts forum member of the year!
With that 4 line post, you covered most driveability issues with the H3



The only thing I will add from iulian98's symptoms: check the u-joints... GL

 

Dang it, I knew I missed something. It's always the obvious stuff that gets you.

 

Sounds like a motor or transmission mount needs replacement...

 

could be a flaky torque converter lock/ unlocking? at those speeds, rpm.

just my first thought

 

100K miles, .... ever cleaned the TB or MAF?

IMHO, hesitation or stumbling at 2000 RPM or so is ignition related. 100K is spark plug change time. Still have the original plugs?

 

Thank you all for the sugestions. I just need to add 2 more things: I have had for a few weeks the error code P0442 (Emission Control System Leak - SMALL), and now P0455 (Emission Control System Leak - LARGE). Could these be the cause for the vibration? (I just order a new fuel cap - I'll change it in a couple of days)
Also, I found this video on youtube - . I can't really see what he does. Any idea what item he is tightening?

 

I never heard of a vibration from an evap leak. That yt video is for a heat shield rattle.. You stated that you have a vibration? Vehicle shaking? Can you feel it in the seat, or in the steering wheel?

 

Nope, unrelated.