Spark Plug oddity ......

[Head Lice]

Going through the 'new to me' TJ .......
Changed out the plugs and discovered something unusual.
All had 0.070+ gaps .... #5 (second from left) had 0.080+ gap.

Installed 3034-2 Champion (RC12PEC5) with 0.035 gap.

 

[Chris]

How was it running before and how is it running now? Any difference?

 

[Head Lice]

I seldom drive 'gaspots' ..... so have little to base a comparison on but, the TJ was surging in 1st and 2nd gear. It started instantly before the plug change, and there was no indication of any ignition problems. With the erosion of tip/ground of the old plugs, I'm wondering if they were installed at the factory ??
Mileage is 96,700 miles / 155,724 kilometers .....

 

[Chris]

Very well could have been factory plugs, it wouldn't surprise me! That gap looks way too wide!

 

[UpperMI]

That's definitely too wide of a gap. The wide gap can mean that a plug wasn't firing (or firing intermittently) or that the voltage had to be higher to drive the spark. My guess is that the surges that you were experiencing were from misfire issues from the gap being too wide. I see this once every couple of weeks on our methane gas burning engines at work. We have active spark monitoring and we can see the voltage increase as the gaps widen.