Engine running little rough?

PREM

MEMBER
2006 HUMMER H2
V8
AWD
AUTOMATIC
31,000 MILES

My engine running little rough and when driving sometimes different sounds coming from exhaust, went to the dealer but they said nothing wrong no any code. Can you please help. Thanks. Hi, thre is no loud backfire from exhaust, its like rattling noise and its only once in a whlie. First year it was running fine but next winter it started idling little rough and its not running that smooth as it used tobe.I have done 25000km service on it but nothing changed.I took it to the dealer two three times but they said there is no any code and its running perfect but its not. Sometimes its running fine but most of the time its running rough. Now when I start it engine is backfiring and its happening once in a while. This backfiring sound is coming from inside the engine not from the tailpipe. Can you please figure out what could be wrong.I am worried may be something is wrong inside the engine like valve or something else. Thanks

3 Replies

DR LOOT

MECHANIC
2,311 POSTS

What kind of maintenance have you had done since 2006? Did it start running rough all of a sudden? And what kind of noises are you hearing from the exhaust? Popping sound? Is it a loud backfire?

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Saturday, May 30th, 2009 AT 6:55 PM

JAMES RICHARD FORTIN

MEMBER
1 POST

My Hummer h2 backfired but when I stop and close the engine and start again is running okay, but if I stop and close engine again and restart he start back fire again. Also sometime i'm trying to start and he just make a quick sound like engine running few second and stop so trying to start again, but wont start doing the same but if I wait 10 minut he finally start again.

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Tuesday, June 22nd, 2021 AT 8:49 AM

KEN L

MASTER CERTIFIED MECHANIC
42,959 POSTS

This sounds like the crankshaft angle sensor or the fuel pump has gone out, when you turn the key to the on position without cranking the engine over can you hear the fuel pump run in the tank for 5 seconds? These guides should help us fix it:

https://youtu.be/dCjmRL3p4Cs

and

https://www.2carpros.com/articles/car-cranks-but-wont-start

Also, lets run the codes to see what come up.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Please run down these guides and report back. Can you please shoot a quick video with your phone so we can see what's going on, that would be great. You can upload it here with your response.

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Tuesday, June 22nd, 2021 AT 9:55 AM