I recently joined and need some advice. I bought my 2007 H2 a couple weeks ago and the dealer had a few items to fix for me. Well I drove it for 3 weeks until the parts came into thier shop and I brought it back for them to work on. 2 weeks later it was completed. 1 of the items they repaired was the classic broken Exhaust Manifold bolt driver side rear. it looks fine with new gasket and all new bolts, wires and plugs appear to be fine jut by touch and sight.
But since the repair the truck is bumping like a cylinder firing slower or missed spark timing. Anyone ever experience this? The dealer acts friendly but I'm not buying thier slow responses as being concerned. Any ideas?

 

Sometimes a plug wire can break internally when being pulled off the plugs. I bet a tune up would cure your problem. Plug wires are easy to replace.

 

push down all spark plug boots first just to make sure they are fully contacting. If not
then Calif Phils response is spot on.

 

Pushed the plugs on fully yesterday and drove with no change so I was thinking wire and plug change was due. Hooked a diagnostic up to make sure the SE light wasn't burnt out also and no codes thrown.
Trying to tread carefully in case the dealer missed or messed something up during the repair. I need to verify they want me to replace plugs and wires before proceeding.
I've only owned 2 none GM vehicles in my life and sold them quickly, so I'm probably more educated with GM than they would be since they mostly sell foriegn cars.

 

You could pull off each plug wire one by one and check each wire to continuity. That would rule in or rule out the wires. It must be something simple or else the computer would be going nuts throwing codes.

 

I'm agreeing here. Had several bolt heads snapped on mine when I got it (thought it was "just" a simple, easy-fix exhaust leak...) and had a local shop repair it. They ended up replacing the wire set as only one pulled off clean. If they pulled yours apart and just rammed the wire back in the boot, could be the source of the misfire. Worth a look.

 

Thanks everyone, problem solved. I mentioned to my local dealer what happened and he said a cracked porcelain on 1 plug could be causing the issue without triggering the SE light. Pulled them today and sure enough, it was exactly that. Not sure how to post the picure but I'll try.