2nd Gen R56 Cooper S Most liked posts in thread: SPUTTERING on cold start

I'd say carbon too. On a cold start the carbon literally soaks the fuel into it making the mixture too lean. Happens on any engine with a lot of carbon in it.

As far as seafoam goes no one has shown any proof that it works. Don't know if it would hurt or help. The fix that does work is walnut shell blasting.

Good luck & welcome to M/A....

 

My 07 MCS was doing the exact same thing. Mine got to the point that it took several tries to get it started.

In my case it was a fuel pump- A known issue and replaced under warranty. There is a service bulletin explaining the issue and warranty period extension. A google search for 'r56 high pressure fuel pump warranty' will yield a lot of folks with the same issue- discussion at motoringfile- and a thread on NAM

Mine also threw the misfire code on my obd reader- the misfire was a symptom, not the cause.

A phone call to a MINI dealer may explain specifically which fuel pump it is, my dealer in San Antonio was familiar with the issue and Robert's your father's brother.

 

Sounds like carbon to me. Additives won't help.

 

Seafoam engine treatment will do the trick. I do it every other oil change to prevent carbon build up.

 

Welcome, thanks for joining Motoring Alliance, the FUN and Friendly MINI Community.

Have you pulled the spark plugs and checked them?

I'd also look at the plug wires, make sure they are seated well.