Spark Plug Boot Fitment

I have a 2007 Yukon Denali. The engine seems to run fairly rough at idle and the tachometer noticeably fluctuates. I asked my dealer to look into it and they indicated that no error codes were stored in the computer, and thus, everything must be fine.

I took a look under the hood and noticed that the third spark plug boot from the front of the truck on the passenger’s side does not appear to be seated as far onto the plug as the remaining seven boots. I attempted to push the boot on further—it is a relatively tight spot to work in—but the boot would not seat any further.

My questions are as follows:

First, does anyone else with the 6.2 experienced a rough idle with fluctuation RPMs?

Second, does anyone have any suggestions or opinions on the noticeable boot gap? Should I be concerned and take it back to the dealer? Should I pop it off and try to reseat it? Would a poor wire connection register an error code in the engine?

I don’t want to mess anything up on this new truck, but always get concerned when there is a noticeable difference in how things fit together. Also, it seems as though such a new engine should have a very consistent idle RPM.

I appreciate everyone’s time and input.

Thanks.

GMCYukonDenali said:

Second, does anyone have any suggestions or opinions on the noticeable boot gap? Should I be concerned and take it back to the dealer? Should I pop it off and try to reseat it? Would a poor wire connection register an error code in the engine?

I appreciate everyone’s time and input.

Thanks.

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That's the #6 plug and it would set a code if it wasn't firing. But it would hurt to pull it off and put back on just to be sure.