2008 Yukon Rough Idle

[YukonCrazy]

I noticed that my Yukon was idling rough while in gear stopped at a stop light. This has been going on for a few weeks now. If your stopped and put it in neutral, I don't notice it. I haven't done or changed anything recently. I replaced the plugs and cleaned the MAF just about 2 years ago. Checked the air filter and it looks pretty clean.

Guess I am going pull the plugs and check each one. If all look good, probably replace the wires. Any different suggestion to diagnose?

 

[JML07denali]

Mine was idling rough as well when in gear. I started with checking the wires. When I pulled the wire for cylinder 1 it was broken on the inside. I guess when I took it in for inspection someone must have pulled on the wire really hard and broke it. I replaced all the plugs and wires and the truck was running smooth again.


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[YukonCrazy]

On a misfiring engine, will a handheld scanner show any codes with cylinder number if there is no check engine light on?

 

[JML07denali]

Yes! That's how I figured out what plug to check. I didn't get a check engine light but the code still came up on my obd II scanner.


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[YukonCrazy]

Just took out the 4 plugs on the driver side and here is what they look like...

Keep in mind, these are only 2+ years old...

 

[JML07denali]

Woah! I would change your valve cover to the updated one. There is a few threads out here with the part number.


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[YukonCrazy]

Woah! I would change your valve cover to the updated one. There is a few threads out here with the part number.


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What is up with the valve cover?

 

[JML07denali]

Read through this it should explain quite a bit.

http://www.tahoeyukonforum.com/forum/showthread.php?p=874571


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[YukonCrazy]

So the only way to verify that I have the old style valve cover is to remove it?

---------- Post added at 12:49 PM ---------- Previous post was at 11:29 AM ----------

CRAP!!!! Just replaced spark plugs and still running rough. Can I say CRAP again?

So what's next?

- replace wires
- clean MAF and TB
- replace fuel filter
- some other POS sensor?

 

[slocaddy]

I think your plugs verified that already
Makes me think I need to check mine.....