2003 gmc envoy random misfire

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hooverrwh
Posts: 2
Joined: Mon Oct 21, 2013 9:11 pm

2003 gmc envoy random misfire

Unread post by hooverrwh » Mon Oct 21, 2013 9:17 pm

My 2003 Envoy is missing, random misfireing 5 out of 6 cyl. some loss of power and not throwing any codes. I've changed the plugs, fuel filter, checked the fuel pressure and also checked the cat. converter and alls good. Also changed the throttle body gasket. It also has a rough idle.....any ideas??

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TerryAuto
Posts: 313
Joined: Fri Dec 11, 2009 8:48 pm

Re: 2003 gmc envoy random misfire

Unread post by TerryAuto » Tue Oct 22, 2013 5:20 pm

If your Envoy has the engine has a misfire on 2 cylinders and a rough idle, then you may have a cylinder head problem. The ignition coils fail on the 4.2L engine but will almost always set a P0300 code in the computer, and the misfire would be most noticeable on acceleration. Read this article on Trailblazer Envoy misfire

hooverrwh
Posts: 2
Joined: Mon Oct 21, 2013 9:11 pm

Re: 2003 gmc envoy random misfire

Unread post by hooverrwh » Sun Oct 27, 2013 8:37 pm

It actually misfires randomly on 5 out of 6 clyinders but never on #1. you can feel it on idle, the misfiring and rough idle and more when going up an incline. I had the trans rebuilt about 12 months ago and 2 months ago the torque converter went bad and I had to replace it. guess I need to do a compression test on it.I don't know who to trust it to here and don't want a shop to start putting parts on it to try and find the problem that way..lol. Thanks for your help.

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