Intermittent Rough Idle

[kent55]

My 2.5i started an intermittent rough idle. As it's idling, about every 30 seconds the does a slight engine jerk and my aftermarket exhaust does a slight pop. Seems to drive fine. But only notice this RANDOM jerk and pop at idle. 

Any thoughts?

Edited April 12, 2023 by kent55

[kent55]

If I'm a complete idiot could Marvel Mystery Oil in the fuel cause this? 

(A few fill ups ago?)

[m sprank]

Sounds like you have a misfire.  I doubt the snake oil in the tank caused it.

[silverton]

I know @Sonder's car is a bit newer, but seems to be a similar issue;

 

[m sprank]

Interesting.  For the price of the part might be good to replace them every 90k-120k.

[kent55]

That's good information. My car has 180,000 miles. I don't think it was ever changed. NGK spark plugs and wires only 2 years old. 

Earlier I was wondering if the Marvel Mystery Oil clogged though fuel pump somehow.

 

Edited April 14, 2023 by kent55

[silverton]

It's been awhile, 10+ years, since I've had MMO in my hand, is it thick or thin?  You'd only need 4-6oz for the size of our tanks, so that's probably half or less of the bottle?  If it's thin, it likely wont matter if you put too much in, if it's thick that could have plugged a pickup.