2007 engine does not run like 2006 engine.

[finall]

Just traded in our 2006 H2 for a used red 2007 H2 SE with 11K miles. Real beauty. But does not sound nice. The 2006 engine was very smooth idling, and had strong pull through all rpms.

But the 2007 engine has a noticeably louder and rougher idle. A bit of a growl. Slight vibration clinking noise from under the hood that was not there on the '06. Sounds a bit like an aftermarket exhaust (but it is stock of course). The growl grows when accelerating from a stop with increased foot pedal travel and rpms, until the vehicle reaches about 30mph. Can't see anything.

The 2006 was noticeably quieter at idle, and smoother at all speeds. No growl.

So the first thing I did was change the new oil that the Hummer dealer 2-litre overfilled during a change to synthetic when I finally got the freshly changed over-tightened and siezed oil filter off. Just after they delivered the 2007 H2 SUV to me. Hopefully this screwup on their part did not damage the engine, as it was only driven this way for 50 miles before I got it home.

I am using the same oil, and the vehicles have about the same miles on them. Threw in 2 bottles of injector cleaner into the tank. No difference.

Has anyone else noticed this difference between the 2006 and 2007 models? Is this growl normal, or does the 2007 have something wrong with it? Seems to run fine otherwise. Just more noisy.

Did anything change from 06 to 07 in the engine, tranny, or exhaust that could be causing this difference?

Help!! Anyone who owns or have owned both an 06 and 07?

Help!! The truck has an appointment with the dealer on Monday for this growl, but I would like to avoid taking it in for exploratory surgery if it is not needed.

[HUMTECH]

They should be the same other than the 07 may have different calibration updates which the 06 didnt have unless it was recently updated. As far as the oil filter being over torqued, no damage not to worry there. Lots of lube shops will do that just to cover there butts. If it was not leaking, no problem. Do mention your concerns with the service manager or shop foreman and have them addressed, if nothing else it will be on file if problems do arise.

[finall]

Hi Humtech,

Thanks for the speedy answer!

Should I ask the dealer to flash the latest update to the 2007 computer, just in case something has gone sideways with the present calibration?

The 2007 has a definite growl (louder, rougher and deeper sounding idle) than our 2006 had at idle. The difference between the '06 and '07 seem to disappear above 1000-1200 rpm.

Are the H2 engines hand built, or for some other reason is there a difference from engine to engine that could account for the different sound tone of the engine? The engine vibration changing with RPM is also different (more pronounced on the 07).

And yes, I hear you about the dealer covering their butt on the over-tightened oil filter. But I figure a newbie did the oil change. I only tighten hand tight. The guy overfilled it too, and this is pretty hard to do on an H2 due to the hole markers in the dipstick end, which clearly show you how full it is.

[HUMTECH]

Def hard to overfill, not smart on their part. As for the calibrations the 07 likely(maybe not) has the latest software already. I myself have never noticed any difference in the model years. As far as i know all engines are assembled by hand(dont think a robot could do it). A slight change in exhaust routing can cause significant changes in percieved noise. We have run into many trucks that after hours of exhaust tuning with weights hung in various spots and slight mods to satisfy customers yet the next truck built the same way has no problems. Tough call and will likely end up as a nff(no fault found) but as i said at least your concerns will be on file if it turns out to be something more

[tomp]

07 has 3.5" exhaust versus 3" on previous years and uses same engine

[finall]

Hey Tomp!

Ok, a different diameter exhaust would definitely account for this sound difference! Good call.

Now, I am curious. How did you find out this difference? Did you measure the pipes? If so, what prompted you to do this? Or did a muffler shop discover this for you on a custom exhaust install? I would sure like to know.

I have been cruising the Internet to see what changed from 06 to 07, but an exhaust change is not mentioned anywhere......