Our MINI has 150k miles on it. On Saturday, we drove about 45 miles on the highway. When we exited the highway and stopped at the of the offramp, the MINI's RPM's dropped and the engine stalled. It started right back up, but the idle was rough and was prone to stalling. We stopped at our destination and waited about an hour. The idling was still rough, but not as bad. We drove it back to our house. It died again as when we stopped at the end of the off ramp. Again, it started back up, but the idle was very bad and it died two more times before we got it to the driveway.

Once there, we opened the bonnet for a quick inspection. I removed the air filter and it seemed okay, but I went ahead and cleaned the filter with some compressed air. I then started the engine again and the idle was still rough. I turned the engine off and left the bonnet open for another thirty minutes to let the engine cool. I then started it up and the idle was normal. We drove back to our garage and the idle issue did not occur during a fifteen minute trio by interstate to our house.

I've already scheduled an appointment at the Dealership for Wednesday, but I'd like to know if anybody has experienced this before. I had read where the HPFP could go out, but from what I can tell those stalling/idle issues are from a cold start. My guess is that a sensor is getting overheated and the ECU isn't adjusting the fuel/air mixture correctly.

On a related note, we had this happen once before at 100k where a non-MINI mechanic performed a tune-up and replaced the spark plugs. That did seem to fix it then, but we did replace the spark plugs less than 10k miles ago, so I donubt they need replacing.

Any feedback is appreciated. I just want to be informed as to what the potential causes could be and how much they would cost. Thanks in advance.

 

I have a rough idle as well, rides fine at speed, but coming to a complete stop it starts to chug but it doesn't stall out like yours does. Dealer noticed some cracking on the intake manifold while it was at the dealer last week and "patched" it up but it still chugs at idle, although unlike yours, it runs fine longer in idle the more I drive, especially after a 10-20 min. drive down the highway.

My guess is as good as yours, the ECU is overcompensating on the air/fuel ratio and maybe it's running too lean to keep going. I have a feeling the same thing is going on in my car, and the only way to fix it is to 1.) Replace the sensor and if that doesn't work, 2.) Replace the manifold. For the record, the dealer quoted me for the manifold work (which includes a port cleaning) at just over $1k, but if you can replace one yourself, I'd suggest it, ECS sells revised intake manifolds for the R56 N14's at $280.

Again, it's a total guess, and I'd let the dealer make that call, but it could be that.

 

Are you getting a check engine light? You didn't mention (or I overlooked it).

Is the idle surging? May be worth taking out your MAF and cleaning it with contact cleaner.

 

The dealer indicates that the coolant pump is leaking and the loss of pressure is causing the ECU to think that the engine is overheating. I told them to fix it, but the constant repairs on this car have me looking towards finding a non-MINI replacement.

 

Glad you have your answer, mine has those symptoms when low on oil.

 

Sometimes these cars are too smart for their own good!
I've seen ECU that monitor coolant temperature but never pressure. Then again, these cars have no temp gauge, oil pressure or oil temp gauges so I suppose that the ECU has to monitor these things for us. I think I would prefer to have my gauges back honestly. Oh and toss in a manifold pressure gauge too so I can keep an eye on things.

Oh well, only so much you can do with such a small cockpit.

 

Wow these cars have some odd issues! Did you ever get a check engine light? Just curious to know if us 'shadetree mechanics' would have been able to have reached a similar diagnosis via code.

 

Can you take it somewhere else? If the coolant pump was leaking enough to be a problem, you'd have a pool of coolant under the car. If it's not really leaking, but it's not really efficient, then the engine would overheat and you'd get a check engine light. That dealer is full of crap and feeding you a story (read "$$$").

 

I would greatly appreciate an alternative to the Dealership, but sadly I haven't been able to find anyone else that I trust to work on it. OKC is a wasteland in that regard. I've had our family mechanic of thirty years work on it before, but it's getting harder to get it in to his shop. He's moved on to custom hot rods and was never really fond of imports. Anyway, I'll follow up when we pick up the car on Wednesday.