Countryman S with 90k on it. Replaced plugs, swapped coils between cyl 1 and 4 and misfire didn't follow the coil.

It will misfire and if it gets really bad (seems to be worse when its hot out and it has been hitting 95 here) it will go into limp mode under heavyish throttle where it has basically no power and is scary to drive. If I sit a gas station for 5 min and restart and it will usually reset itself. I can feel the misfire ususally higher in the rev range. Starts and idles totally normally. The car is completely stock except for a cone intake filter it has had since about 30k miles.

My next two guesses are a bad fuel injector or mayb needs the carbon cleaning (These are direct injection right? My car is a bmw 335 and they have these issues due to the DI)

Looks like the injectors are a PITA to get to, so if that is the next place to look I will probably get one and just replace it while I'm in there, saw them on pellican parts for 66ish bucks.

Anything else you guys would look at? Am I on the right path with the injector?

Thanks!

 

Can't help with your misfire, maybe if we knew which code(s).

If you pull an injector, be prepared to get a special tool to get it back in. The seal is teflon and needs to be compressed, or it's next to impossible to re-install.

 

Have you done a compression test?


I'd start there before throwing parts at it.....

 

The code is "misfire cyl1" and also once pulled a "random cyl misfires" code but that never came back. Would the exact code number help?

I haven't done a compression test, I can tomorrow. Are there common problems with this engine that would be that serious?

 

Thanks for the heads up on the special injector tool, I wouldn't have had any idea on that. Is there a goto cheap place to get it?

 

While injectors sound like a logical place to look, they are not very often the source of this issue.

Carbon buildup will maintain enough heat to ignite fuel when its not supposed to be......Think of it like a red hot ember in a fire pit.