I have a 2007 H3 with 160K miles that I recently purchased. It recently stated shaking and RPM going up and down at a stop light. That is the only time that I feel the shaking. There is no Engine Light. I took it to a mechanic and they did a compression test and said I need a new engine. I am reaching out to you pros for some advice. I have no details of what they checked. If you tell me what to ask them I will ask.

 

What was the PSI for each cylinder? Did it drive OK before the "recently started shaking?" When was the last time the Throttle Body and MAF Sensor were cleaned?

READ this.... Acts like it wants to stall/rough idle -No CEL -What To Do:

 

I have no idea when the TB or Mass Flow was cleaned. I will do it today. But the info for PSI is
1 = 165
2 = 165
3= 165
4 = 155
5 = 150
The leak down was 50% - don't know what that means but they said so.

 

valves could be gummed up with carbon.

 

Find a new mechanic.

 

I need a Hummer H3 professional in NW suburbs of Chicago.

 

Why find a new mechanic, is the PSI in range? I thought the specs were 215

 

Lol,

I'd start by running some techron through the H3.
I'd also replace the spark plugs and coils.
I'd take the time to clean the throttle body and the maf sensor.
Lastly, I'd take the time to put a new air filter in it.

165 to 150 .

I've seen engines run with much less compression.
I

 

I'd do a fuel induction service and be done.

 

I bought an '07 H3 yesterday with 125K on it. The main reason I bought it was because I've got 180K on my '04 Chevy Colorado that's still running with the same 5 cylinder motor. I had similar issues as you with the RPM's going up and down especially at low/idle rpms. I cleaned the throttle body and my problem was solved. Start there. I found vids on youtube that walked me through it. If you can't find hummer vids look for IL5 Colorado vids on cleaning the throttle body. Good luck and please let us know how it turns out.

Uzi