Hi folks,

My wife's 2007 R56 S has recently started to misfire at idle and have significantly reduced power. 1st and 3rd cylinders appear to be misfiring. Took the spark plugs out last night and they all appear to be fine. Car has had a walnut blasting in the last 10k miles. Is there anything else I can check to self diagnose before taking it into the $tealership? We just took the car on an 800 mile round trip vacation over Memorial Day weekend without any problems, and the next morning this happened.

 

Fuel pump/ Hight Pressure Fuel Pump..?

 

Swap the coil packs around and see if the problem follows any one or two coils...

 

These two beat me to it, by changing around the coils might reveal that the misfire follows the coil. I would say it's a 50/50 bet that it's either one of these issues, did it misfire when engine cold or all warmed up?

I'll bet it's the HPFP which Mini USA extended the warranty on it for 10 years or 120k miles. If it's the coil it's not that expensive to replace.

 

I will jump in on the HPFP band wagon.
Coils don't randomly fail in pairs.

If swapping coils (and resetting all lights - critical, as the DME will shut down ignition to misfiring cylinders and confuse the results of the test) doesn't move the mis-fire codes to new cylinders, it is probably the fuel supply problem. Or something significantly more expensive with engine internals (BTDT).

To get HPFP covered under MINI's 10-year warranty, you need to take it to the dealer. Unfortunately, if it's something else, they will charge you for 1 hour or "diagnostics". Still worth the gamble, since HPFP is pricey, and knowing for sure what the problem is will help you to decide whether to DIY it later if it's something else.

Please do NOT drive the car with misfire (on 2 or 3 cylinders), as it will spay un-burned gasoline into the cat and may bring forth a very pricey replacement ($$$$).

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Typically Mini USA will not replace the HPFP unless you're throwing codes specific to the HPFP or if they can find nothing else wrong. They do say once they install a new HPFP that if it gives problems later you've already used the one time warranty for the HPFP.