2008 GMC Envoy Denali 5.3L - Miss & Smoke

Specific repair issues for GM RWD trucks, SUVs & vans
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92zman
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2008 GMC Envoy Denali 5.3L - Miss & Smoke

Post by 92zman »

We have a 2008 GMC Envoy here that after u drive it for a while it will start to smoke and miss. The miss is cyl 5,7 every time.
Have had the valve cover off and it all looked good. Did find one vac leak and fixed it but did not fix it. U do have to drive this thing for about 15 min for it to start doing it. If u keep driving it it will go away. Had to clean the srean under the oil psi switch when we frist got it. This is our truck. Been looking off and on now for a few months now.
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fortknoxx
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Re: 2008 GMC Envoy Denali 5.3L - Miss & Smoke

Post by fortknoxx »

the coil might be over heating and sending wrong/intermittent/no fires to the plugs. Allowing fuel to collect unburned in the not firing cylinder. Then BAM!
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steven kiser
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Re: 2008 GMC Envoy Denali 5.3L - Miss & Smoke

Post by steven kiser »

watch O2 signal. If it tanks it will kill cylinders
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