Rough idle / misfire cylinder 3 on 2007 Tahoe

a_kraker99

Original poster
Member
Nov 13, 2012
3
I am logging a misfire on cylinder 3 only white at idle. I have changed the plugs and Swapped that coil / wire but still get a misfire. I also tried some techron in case it was the injector. Any idea what it might be? a vacuum leak should create a random cylinder misfire right? Could the injector just be dying?
 

Wooluf1952

Member
Nov 20, 2011
2,663
Milwaukee, Wisconsin
a_kraker99 said:
I am logging a misfire on cylinder 3 only white at idle. I have changed the plugs and Swapped that coil / wire but still get a misfire. I also tried some techron in case it was the injector. Any idea what it might be? a vacuum leak should create a random cylinder misfire right? Could the injector just be dying?


:tiphat: Welcome:tiphat:

In case you haven't heard:
http://gmtnation.com/f5/welcome-gmtnation-com-heres-story-226/

More info about the truck may help.
Mileage?
Not sure, but if the injector was going bad, wouldn't it be more likely to show up under power rather than just at idle?
 

a_kraker99

Original poster
Member
Nov 13, 2012
3
120k miles. 5.3l flex fuel V8. Always ran regular gas.

You make a good point about it misfiring under load.

It is easy to take the injectors out and swap them just to rule that out?
 

Blade

Member
Nov 20, 2011
257
a_kraker99 said:
120k miles. 5.3l flex fuel V8. Always ran regular gas.

You make a good point about it misfiring under load.

It is easy to take the injectors out and swap them just to rule that out?

If you are sure that is has spark then yes the injector would be the next logical step. After that is a compression check so really hope it's the injector. Techron will not clean out a fouled injector.
 

a_kraker99

Original poster
Member
Nov 13, 2012
3
Well the misfire goes away when the engine is warmed up so compression probably wouldn't make sense right? It is only misfiring while not fully heated and at idle
 

bluesilverado

Member
Dec 8, 2011
6
gm has a tech bulleton on this my boss has the same truck had the same problem it is a valvecover issue i bel:smile:ieve
 

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