I have a 2006 MINI Cooper S. a couple days ago it started idling really roughly when I started the car. after a few minutes, the car would idle properly. The fuel level was at about 1/8th tank. I have since filled the gas tank in the event there was an issue with the fuel. It seemed to fix the issue but yesterday the same thing happened again. while driving yesterday, I was decelerating as I approached an intersection with vehicles stopped in front of me. The engine stalled. It started up right away. This morning, I couldn't get the engine to start. as I started the car it turned over then sputtered like it was going to start but never did. I can do basic mechanical repairs but when it comes to the more complex issues, I do not have experience with troubleshooting/repairs.

 

im not an expert either, but i would suggest, start by purchasing a yellow bottle of HEET. add that to a half tank of fuel. also, when temperatures are around freezing, its good to keep the tank at least half full. if theres moisture in the fuel lines, this will help.

beyond that, i would reccomend adding a little more info. for instance, does the car sit for days/weeks at a time, or is it driven daily? how many miles are on it? has the battery/alternator ever been replaced to your knowledge? what octane fuel do you run? has the vehicle had any excessive bumps recently that could cause an electrical connection to come loose?

if the HEET doesnt help, i would reccomend checking your air filter, and spark plugs. cars need air, fuel, and spark to run. if its running fine, and has the symptoms you describe, it is most likely one of those. fortunately all relatively cheap, diy fixes.

frozen fuel lines, wet/dirty air filter, fouled/corroded spark plugs can all cause a rough idle, and in worse cases a stall.

theres also the possibilty that your coil pack lead #3 is corroded. this is very common with our cars.

 

Update and answered questions.

it's a 2006 with 51,000 miles on it. The battery has been replaced once. the issue isn't power. I used a bottle of Heet. It didn't have any effect at first.

I contacted the MINI dealership service department. after talking to the manager, he recommended the following. replace the spark plugs. replace the air filter. change the oil (since it's due) and to change the oil more often since I don't put that many miles on the car.

The car is driven daily. as far as fuel, I use the mid grade fuel. The big thing I think that may be affecting it is that the fuel was recently reformulated. I may have to switch to the premium fuel to get something that works decently.

I finally got the car started when the weather warmed up to around 10 deg. it was 1 when I tried to start it in the morning. Once started it idled roughly again but finally I got it running smooth. It has stayed smooth for the most part since. I went to the auto parts store and got them to read the codes. they came back as 1st cylinder misfire. I got new plugs and they are in. the car started right up but still seemed to run a little rough.
hopefully the Heet does it's job and helps with the remainder of the gas before I switch to premium

 

Misfire on cylinder 1.....
And your failure to run premium fuel.. (Ok...midgrade is USUALLY 89...SO MIGHT BE OK UNLESS YOU GOT A TANK OF OUT OF SPEC FUEL).
Leads me to believe you COULD have a burnt valve....
Very common when folks use less than 90 octane....compression check will verify this or rule it out.
Rekember .....cheaper/lower octane gas might save you 2-5 $ on a fill up, but cost you 1500$ on a head job....
Good luck.

 

I'd go with a set of new plugs in the stock heat range. Also put a set of plug wires on. Check & clean the coil pack terminals when changing the wires. Always use premium fuel. I'd be very surprised if you have a burnt valve. The car would never run correctly if that was the case.

 

Alternately...
It might have been just so darn cold, the fuel was not atomizing fully...and some dripped...causing tge misfire....
That is one reason "heet" red, aka isoproponol....can help...helps Increase the fuels vapor pressure/volility....helping the fuel evoprate....Helping the start...

 

Also watch out for gas with ethanol in it, if you are using mid grade most likely you are getting 10% ethanol and that stuff is horrible. I've learned Mini's just don't like cold weather too. A month after I had bought mine it would not run, or would only run in "safe" mode, and I was told by the dealer that it was just because of the cold and it is common.