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Registered User
Join Date: Jul 2009
Posts: 44
2008 Mini Cooper S R56 Misfire all 4, rough idle, barely starts when cold

Hi guys

I'm running out of hair to pull out. I have an 08 Mini Cooper S turbo 98k miles automatic.

When it's cold it barely starts and i have to step on the gas. still then it struggles. once the car is warmed it runs fine. My Rpm struggles at times where it practically shakes the car. When it's cold and I drive it after a couple of minutes of turning it on, it has a hard time changing gears so i have to use the paddles. Once the car is warm it drives fine, but still idles rough just not as bad as when its cold.

I have replaced All spark plugs, High pressure fuel pump, thermostat and housing. Not really sure what else it could be. Bluedriver OBD code is just P0300 (random/multiple misfire) and P0301, P0302, P0303, P0304 each cyl misfire

Any help would be great. Thanks in advance

Old 01-09-2019, 11:50 AM
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Dmitry at Pelican Parts's Avatar
Join Date: Aug 2016
Location: Los Angeles, CA
Posts: 5,437
Have you checked the injector's current and voltage with a scope? The transmission issue sounds separate. I have also read that the coil-packs on the R56 cause issues - esp with cylinder 3 and 4.
Old 01-10-2019, 12:32 PM
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Registered User
Join Date: Aug 2018
Location: California
Posts: 14
I have 2 R56 non-turbo cars, but I have had many hot rods, and muscle cars in my lifetime.
There are many things to look at for diagnosing and rulling out potential performance problems. I have learned with my coopers how critical the timing chain is to the car running smoothly. The valvetronic system working perfectly, oil pressure, Lifters(tapets), Injectors, Cam sensors, Vanos sprockets and Selenoids and engine vacuum.
*Something that I recently discovered was how critical the crankcase vacuum is to the car running good. Do this test, pull off the oil filler cap, while running, and wait for a few minutes. It should die from lack of vacuum. It should almost start stuttering within seconds of removing the cap. You cold have a bad PCV valve( part of the valve cover) that is leaky, could have a bad oil filler cap seal or its just missing. could be a bad PCV line that runs from the valve cover to the intake. Could be a bad seal around a cam sensor in the valve cover or just a bad valve cover gasket. It might be more serious than that. But with good compression, to have a whole string of misfires, that sounds like a vacuum issue to me. Especially since it gets somewhat better after the car warms up, seals tend to expand and close small gaps when warmed.

The big 3 for misfires that you need to troubleshoot are: Compression, Ignition and fuel delivery. With the R56, vacuum plays a big role.
Good luck

Last edited by 08&09R56coupes; 01-17-2019 at 08:37 AM..
Old 01-17-2019, 08:34 AM
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Registered User
Join Date: Oct 2019
Posts: 32
When is the last time you have had the valves walnut blasted? Run a compression check cold, I would bet you have excessive carbon build up at 98k and you have some valves not sealing. I own 5 minis 2005 MCS, 2007 base r56, 2007 Cooper s and 2 clubman S models. I’ve been buying them on the cheap and doing valve jobs. Two of the 5 had burnt exhaust valves where 1/3 of the valve was missing. The clubman S I bought is hard to start I’m going to clean the valves, I’m betting it sill solve the issue.

If you see a p0300 it can also mean a vacuum leak. Check the compression you should be in the ballpark of 150psi if there is more than 10% variance across all 4 cylinders you need to look into pulling the head or having the valves blasted. Doing it yourself isn’t overly hard, fighting the turbo manifold is the biggest PITA.

Old 10-26-2019, 10:02 PM
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