Had only 5 days and already check eng light on random miss fire any thoughts ? runs lumpy at first start up then smooths out after warm up . PLEASE dont say fuel pump , 500$ ouch!!!

 

check for dirty throttlebody,clean with throttlebody cleaner not brake cleaner and also maf could be dirty

 

Well, let's start with some forum basics, then we can get to your issue if you can't figure it out.

Always READ before you post anything. You have questions about an H3, they go in the ..... H3 section. Crazy isn't it? If you would have read the top sticky post in the General Hummer talk section you would have seen this: https://www.hummerforums.com/forum/g...ns-here-33068/

Use the search function, there is a ton of good information about your issue. BTW, a CEL is piddly squat and easy to correct 99.6% of the time so do not let that freak you out like some of the fly through by night people looking for how to maintain a car basics 101 stuff.

If your truck through the CEL, it would be nice to provide the actual code(s) if threw so we can all cut to the chase and provide some to the point help. Otherwise, I do not bother guessing, I can do that when I buy lotto tickets.

If after you have the code(s) and searched you still need help, lots of folks on hare will be glad to pitch in.

Check this search I just did for random misfire. Hummer Forums - Enthusiast Forum for Hummer Owners - Search Results

 

start by checking:
spark plugs
ignition coils
fuel injectors
vacuum leak
air filter
Also, only use top tier fuel, clean the throttle body, clean the maf sensor and perform an induction cleaning, and keep that engine oil clean with full synthetic oil. GL

 

What did the code say? I had the same thing at 60,000, was the "misfire cylinder 5" warped head. Do some searches on it before you dump a lot of time and money at other problems, applied to certain VIN numbers and is covered by GM.

 

if the Vin is within the problem identified period, Are you saying a 2006 will be covered by GM still?

 

rotfl! :d

 

I understand that you volunteered information, but at least make an effort to provide accurate information. The I5s do not suffer from a "warped head". The service extension was to 06s with motors built before March 31, 2006 was due to some valve seats not being properly hardened. That service extension (which was covered by GM), expired years ago.

From an almost 5 year old post of mine:
"The S/Ns affected is any 2006 H3 lower than 287591 .... the first one started with 100,001, your truck build date will be Nov. 06 or earlier. Not all have the problem, but some could. The head issue affected not only the I5, 4s and 6s were subject to the same issues. Call GM with your vin# and build date (from the sticker in the driver's door jam) and ask.

Just in case you're gonna say, wow they didn't even build that many 3s? The VINs are assigned at the same shreveport plant building Colorados and Canyons. Their VIN sequence unit #s are mixed in and subject to the same TSB re: the head/valve issue.

The recall and extended warranty was for very early 2006s, those with the 3.5L L52 Motors built before March 31, 2006. That is not to say some 3.7L LLRs have never had a valve or head issue. All the Atlas motors built since 4/1/06 have the new hardened valve seats."

DO NOT jump to the conclusion that you have a bad head because you get a simple misfire code. Paranoia solves little. I would suggest that you contact GM if and when you have a diagnosis from a GM repair tech that your I5 has a bad head to see if they will cover some part of the costs under a good will situation.

 

Very good post , thanks