When were the plugs changed in relation to when your problem started? Just like any other part, you can get a bad plug, and if the plug was dropped it could be cracked.....

How much does one spark plug cost and how long does it take to change it? When/if you change it.... look at it.

 

if you dont have any of those symptoms then i dont think is head gasket, my hummer at stop light the motor never stay complete steady always shake a little but if you read manual on ac section this is normal, as for check engine light coming on, sounds like u have bad electrical coneccion or to low rpm. does check engine light is on all the time?

 

the engine did this with the old spark plugs which i checked and werent that bad. i know changed all plugs to new ones and it still does the same thing. engine light stays on and once in awile at a long light it will skip and engine light will flash for a bit. i had it put on a complete scan at the dealership and nothing came up other than a multiple misfire and a irregular short in the headlights. dealership came up with conclusion that i must have gotten some bad gas cause it runs great they said. put methyl hydrate in to see if that will fix it so time will tell i suppose.

 

Not the gasket. Dealer said its common problem with the 5 cylinders.
I had the same error code.

 

Is there a service bulletin on this issue?

I have the 08 VVT and have not had this issue,,yet..

 

What's a VVT?

The 08s have either the LH8 (5.3L) or the LLR (3.7L).

Service bulletin? Closest thing for anything post 06 is the dirty fuel injector bulletin.

Atlas motor misfires: 1) bad valve spring (weak or broken); 2) worn or bad valve seat; 3) broken valve retainer; 4) cracked/bad valve; 5) bad head gasket; 6) bad spark plug; 7) bad coil pack; 8) dirty or clogged fuel injector; 9) PCM fuel management program glitch; and, 10) even a a bad valve oil seal if worn enough. All can all cause a misfire from negligible to violent at idle or under load.

A dirty MAF, dirty Throttle Body, bad O2 sensor, or bad cam position sensor can cause similar symptoms with a rough idle or false stall sometimes mimicking a misfire and can be read by the PCM through knock sensors as a misfire .... which usually shows up as a random misfire P0300 rather than cylinder specific.

#2 was the subject of the 06 TSB (the S/Ns affected is any 2006 H3/Colly/Canyon lower than 287591) for all L52 motors built before March 31, 2006.

So, you do the easy stuff, and if that doesn't clear it up, go to the dealer.
If you have a local shop that has the time to put the vehicle on a scanner and allow it to reach operating temp, you can watch all the sensor, fuel and spark data to see if you/they can spot something not like it is supposed to be.

Good luck.

 

Yeah, I know about the 5.3 LS based engines.

The 3700 is a vvt (variable valve timing exhaust side only) motor..

It's also the only VVT engine ever offered in a Hummer anything.

I asked because that's what I own..

A service bulletin is something some manufactures sometimes put out when they are aware of various problems surrounding one of their products.

Sometimes there are recalls listed in service bulletins..

Though I am somewhat new to the Hummer brand I've been building and around GMs' for over 20 years..

Oh and you forgot the GM service bulletin for the HVAC blower pig-tail, which not only effects the H3 but also many of their full size pickups..XD

As well as the hood louver(sp) recall for the h3.

 

You forgot that the L52 3.5L (3500) is also VVT, so the 3.7L is not the only VVT engine ever offered in a Hummer as 2006 H3s all had the L52.


BTW I knew where you were going with that, just having some fun with it.

 

My bad.. I never read up on the 3500 since I don't have that one.. Oops!

t'was a noob blunder..

 

This happend to me. Believe it or not I ended up changing my spark plugs to champion platinium and it went away. Change your plugs to them and see for yourself. I had the same exact thing. I even changed my plugs twice to iridiums and it kept happening.