2011 Mini Cooper S with 87k miles and has a random misfire. Plugs and coils have been changed. Took the intake off and it's only got a couple spots of carbon build up, overall pretty darn clean. HPFP was changed appx 3 months ago under warranty. Nothing other than misfire codes. Any ideas?

 

What specific codes are you seeing?

 

Initially 300; 301 and 303. All Plugs and engine coils were replaced with new and it misfired on 2,3 and 4. Not other codes have come up.

 

Get a new PCV hose. It may be leaking, even if it is not the cause, it's cheap and since the car has 87K, it will likely leak soon.

It is item #1 in this diagram: http://www.realoem.com/bmw/enUS/show...diagId=11_3915

 

R56 LCI does not have that hose!

i say, clear the codes and see if they come back up. is the car shaking like it is running on three or two cyls?

 

It runs like normal at idle and slow acceleration. Codes have been cleared but are back as soon as I accelerate hard or try to maintain speed up a hill.

 

I'm having same problems, but only have a misfire on cyl #1. about to order coils and plugs.

 

OEM coils or aftermarket ?
I realize plugs were new, but have they been checked/make sure torqued correctly and 1 is not loose....

 

Could be a myriad of causes. My loss of power and misfire was cured by installing an uprated timing chain tensioner (yes I know, it sounds freaky that my timing could be out just due to this part) which cured the hardly audible rattle at the same time. Feels and sounds like a new engine. Chain stretch came in at 67mm so no need for full chain replacement yet.

 

I replaced my chain and tensioner. I also measured mine it didn't seem different from what I had if at all. Came to the conclusion if I take it out again I'll stick a new chain in regardless.

 

Oh, I'll add this. My cams definitely needed to be adjusted.

 

so I took it to the dealer and it came down to plugs. Unfortunately, I was either lied to or screwed by the first mechanic because he supposedly swapped the plugs and coils with new while trouble shooting and still had the same issue. The most expensive set of spark plugs ever! Plugs and thermostat ran me $1300!!!

 

one word....WOOOOW!