Has anyone experienced rough engine idle with the 3.7L I5? My H3 has 14k miles on it and the dealer is telling me this is normal. The dealer found no codes and says the engine is running normally.

 

Uh, ya. At some lights the steering wheel vibrates so bad I grab hold because I don't want another driver seeing it. Other lights, maybe the next one, it's smooth as can be. Cold start-up is very rough. Warm start-up, not so much. I can't seem to find a pattern on when it's rough and when it's not. I've followed every bit of advise I've seen on here without much luck at all. My next step, possibly this week, is taking it in so they can tell me it's normal.
Oh, mines a 2007 with 23,000 miles on it.

 

My 2007 with 23,000 miles does the same. Maybe not normal, but typical?

 

I don't get how a new truck with such low miles can idle so rough. Steering wheel is vibrating so bad. Let us know what the dealer tells you.

 

Uuuuh............... because it's a 5 cylinder! This is old stuff, comes up many times, mostly from noobs.

Here is the last one, read it, realize what the power plant is and how it behaves. Relax and enjoy.

https://www.hummerforums.com/forum/s...ad.php?t=17113

 

i own a 2007 h3, bought it new, has 75 thousand long driven miles, this is the first winter that the cold starts are very load and noisie, i mean like an old washing machine for like 5 minutes, then gets quiet and runs great, just very load, doesn't run rough, load. i found at amazon, a oil pan heating pad that mounts on the bottom of the oil pan, i had to clean it and it sticks very well and also has a thermastate on it. it measured 4 inches by 6 inches and fits nice! now, the cold starts are still noisie, but only for about 1 minute! so this heater pad does work to ease the cold weather starts for longer engine life!,,,,but still worrie about break downs on my long trips tho, never felt this before now!, now that theres no hu,,er places to get service at in the boone docks!

 

Mine is a bit rough, but much better than my 2005 z71 4x4 canyon crew cab was with the same engine. Some things that helped mine run much smoother:

o Took throttle body off and cleaned it with some throttle body cleaner - 45 min job and pretty easy. It was pretty black after 28,500 miles.

o ran some stp fuel system cleaner thru the tank... Engine ran a bit rough during that tank, but got MUCH better on the next tank full.

o I quit using speedway gas. Noticed an improvement switching to mobil, marathon, shell, etc (this change may be perception only).

o I notice smoother idle with a full tank of gas - giant liquid dampener.

o I also changed my air cleaner element to the K&N that fits the factory box.

My idle is not perfect, but after changing a few things, it is much improved. Another solution is to let go of the wheel when you are at a stop...

 

have it scanned at auto zone or anywhere you can and see if you are having a misfire in a specific cylinder...

dealer told me same thing...no codes...after some argument admitted there was a misfire 15000 times in number 1....told him to change coil...they wouldn't cause the computer said it was ok....DUH>

so I took it out traded with number two drove down to autozone and guess what? misfire in 2 but not throwing code...

changed with new one...total time 15 min for everything..78 bucks no more idle issue


good luck man hopefully it is something you can find and fix.