I moved from Florida (sea level) to Albuquerque (~5k feet) and I'm getting some engine stumbling/misfire on hard acceleration in my 2012 Countryman S All4 as well as my wife's 2010 Clubman S.

Some background, back in Florida I was getting similar stumbling under boost when my car hit around 55k miles, so I put in new coils/plugs which fixed the issue. Her car, same thing right before we moved, around 50k miles on the odometer, new coils and plugs. No problems at sea level, but since moving to Albuquerque, it's started again, though it isn't always present. Early in the morning, or if the car has been in the shade and the engine is cool, it runs fine. Sitting in the sun/heat soaked, it becomes especially prevalent. Moderate acceleration is fine, but if you stomp on it, it'll stumble briefly and then go. Neither car has thrown any codes.

My gut feeling is that the spark plugs I put in aren't up to snuff. I used Amazon's vehicle fitment guide to find plugs vs ordering from a MINI-specific site. I ordered and . I don't know enough about spark plugs to know whether this could be the culprit.

Other thoughts? Her car is stock aside from an intake, and mine has a bigger intercooler and JB+. Maybe it's just a symptom of the hot, dry air, but I don't remember this problem when we lived here previously (both cars were purchased in Albuquerque).

 

The plugs for your R60 with mods should be


Gapped at 6mm

Also, what brand Coils did you install? these cars are pretty picky about coils.

 

These coils in both cars: Delphi GN10328 Ignition Coil https://www.amazon.com/dp/B00CJFLOJU/

I checked the gaps on the plugs when I installed them, though I don't remember the exact value. All were good out of the box except one that got bent during shipment. Going off memory, but I think I gapped them to .032".

 

Your gap is way too wide... needs to be .024-.026. At boost the flame is being blown out. I used a set of the Delphi coils about a year ago on my 2012 R60. they lasted 5 months. I went to Bosch and haven't had an issue.

 

Thanks, I'll try reducing the gap and see where that gets me. Hopefully that helps, if not I'll try different coils.

 

Just to chime in while I have no experience with Minis and spark plugs I have some 1st hand and 2nd experience with some other brands of of cars and spark plugs.


Most recently my 2nd hand experience is a car owner replaced the factory plugs with some that while some chart said the plugs were suitable replacement for factory plugs proved to not be the case. After looking into various other possible explanations and having no success in addressing the engine's behavior the owner had to remove the new plugs and replace them with factory plugs. This cured the engine misbehavior.

 

Yeah, I was hesitant to take Amazon's word on which plugs would work. I might order some OEM plugs and hopefully be done with it.

 

I checked the gaps this morning and they were already at .026". I think I'm going to order some OEM plugs and see where that gets me.