Rough idle / misfire cylinder 3 on 2007 Tahoe

[a_kraker99]

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]

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?

Welcome

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]

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]

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]

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]

gm has a tech bulleton on this my boss has the same truck had the same problem it is a valvecover issue i believe