Slightly long winded one this but my daughter has a 2008 Mini One Auto with the 1.4 (N12) engine.
All had been running well with it till last week when she pulled up at a roundabout and it cut out on her (no issues or rough running prior to this). Long story short but I got it going by adding some revs at start up and managed to drive it home (she's a new driver). Whilst driving it's ok, power delivery feels normal and it's not rough sounding or any rev surging or anything like that, but come to a stop and revs at idle aren't smooth and seem to drop slightly too low and engine will try and cut out on you. Start up is as above, when the engine is warm it needs some revs to get the idle above its stuttering and then will drive ok till you stop again. It fires up 1st time every time, it's just whether the revs drop and the engine stalls.
Fortunate to have a friend who's a mechanic and we've tried several things to resolve this but no joy so far.
First off there is no engine management light on at any time during the issue. We did initially have 2 fault codes, 1 for the downstream o2 sensor, 1 for mass air flow (plausible).
We started tackling some of the common issues, changed the 4 coil packs as they'd never been done as far as we could see from service history, checked the camshaft sensors, we swapped out the o2 sensor (which cleared that fault code) and started looking for vacuum leaks (haven't found any damage via visual inspection plus we sprayed a liberal dose of brake cleaner around and got no change in revs).
Next we looked at the throttle body. Actually thought we'd found the cause here as the gasket had a slight crimp to it and we managed to pick up a 2nd hand body and replaced both the body and gasket (service history showed it had been cleaned in 2019 so guess not quite refitted correctly at that point). Anyway, once we changed this out the Mass air flow error message also disappeared and we've driven it a couple of times since with no return of the message. We also used the Service menu to relearn the idle after swapping things out. However, the engine rough idle and stalling still persist but now with no fault codes to look at either.
Just wondered if anyone has had anything similar with an N12 engine and has suggestions of where else to look. He's mentioned having a look for any chain stretch but we've not gone that far yet. Wanted to see if anything else is common fault on these that might be causing the issue.
All had been running well with it till last week when she pulled up at a roundabout and it cut out on her (no issues or rough running prior to this). Long story short but I got it going by adding some revs at start up and managed to drive it home (she's a new driver). Whilst driving it's ok, power delivery feels normal and it's not rough sounding or any rev surging or anything like that, but come to a stop and revs at idle aren't smooth and seem to drop slightly too low and engine will try and cut out on you. Start up is as above, when the engine is warm it needs some revs to get the idle above its stuttering and then will drive ok till you stop again. It fires up 1st time every time, it's just whether the revs drop and the engine stalls.
Fortunate to have a friend who's a mechanic and we've tried several things to resolve this but no joy so far.
First off there is no engine management light on at any time during the issue. We did initially have 2 fault codes, 1 for the downstream o2 sensor, 1 for mass air flow (plausible).
We started tackling some of the common issues, changed the 4 coil packs as they'd never been done as far as we could see from service history, checked the camshaft sensors, we swapped out the o2 sensor (which cleared that fault code) and started looking for vacuum leaks (haven't found any damage via visual inspection plus we sprayed a liberal dose of brake cleaner around and got no change in revs).
Next we looked at the throttle body. Actually thought we'd found the cause here as the gasket had a slight crimp to it and we managed to pick up a 2nd hand body and replaced both the body and gasket (service history showed it had been cleaned in 2019 so guess not quite refitted correctly at that point). Anyway, once we changed this out the Mass air flow error message also disappeared and we've driven it a couple of times since with no return of the message. We also used the Service menu to relearn the idle after swapping things out. However, the engine rough idle and stalling still persist but now with no fault codes to look at either.
Just wondered if anyone has had anything similar with an N12 engine and has suggestions of where else to look. He's mentioned having a look for any chain stretch but we've not gone that far yet. Wanted to see if anything else is common fault on these that might be causing the issue.
