Hey all, long time lurker, first time poster. I am about at my wits end.

I have a 2010 "justa" Clubman, N12, 110,000 miles. I am having rough idle ONLY when the engine is up to temp, after about 20 minutes of driving. If the vehicle is driven for a bit longer, the problem progresses to stalling. Idle improves a little with the A/C on. It always starts right back up, but I have to give it gas to keep it going. Once it cools down, the problem goes away.

Also has engine codes P0102 most often and sometimes P0101, P0100, and P0103. Usually when I get all the codes for random misfire and other cylinder misfires it is accompanied with a P2187 for too lean at idle bank 1.

Plugs, coils, and spark plug wires have been swapped to no avail. Compression is good and intake was scoped and valves were free of buildup. Coolant temp sensor was also replaced with no improvement. MAF sensor and throttle body were cleaned with CRC MAF sensor/throttle body cleaner. MINI dealer cannot tell me what was wrong with their diagnostics, but tried to tell me it might be a weak valve spring, which doesn't make since to me that it happens only at idle rather than valve float occurring at speed. My local mechanic said the injectors and fuel pump tested good but I suspect that was done when the engine was cool. Tested for vacuum leaks spraying carb cleaner around likely spots with engine cool, but I'm not convinced it's not a leaking intake manifold.

Timing chain recently replaced, water pump, pipe, thermostat, as well along with a coolant flush and fill.

Looking for any advice on what to tackle next or what might be the most likely culprit.

 

where are you located?

 

Evansville, Indiana

 

quite a distance...lol

unplug the MAF and start the car, what happens?

 

Unplugged and started tonight, idled rough for a few seconds as the computer adjusted (I assume) then idled fine while cold. Will update after I drive to work tomorrow and get the engine up to temp with the MAF unplugged.

 

I suggest you driving it locally to see how it responds. Order a new MAF in the meantime.

 

Alright, drove to work this AM, pulled over and unplugged MAF once symptoms started. Drove the final mile to work and symptoms were the same, maybe a touch worse, died a little faster.

 

so there was "no" difference with and without MAF. That leads me to a fualty MAF.

Also a another fellow NAM member had something similar, in his case the vacuum hose from the intake to the airpipe was cracked and inconspicuous.

 

More for the benefit of people looking for an answer to their hot idle misfire problem. If you have an n12 engine that is suffering from a hot idle misfire, it is likely that you have a loose inlet valve seat on the cylinder that is misfiring. Why the n12 presents the misfire while the n14 doesn't is because of the VVT technology. In the case of the n14 a loose valve seat will destroy engine while the n12 gives you a warning through a misfire at idle but if you fail to resolve it, the engine will eventually be destroyed. Through VVT the inlet valve lift at idle is very shallow and this results in the valve with the loose seat not sealing causing a loss of compression - resulting in a misfire. When you remove a cam sensor the VVT is disabled and the valves move to full lift at idle and the misfire stops. So if you have a R56 that is misfiring at idle when hot, try disconnecting a cam sensor and if the misfire stops, chances are you have a loose inlet valve seat. A lot of engine specialists are aware of valve seat issues with the R56 however too few people have tagged the loose valve seat issue with the hot idle misfire. My partner has a justa that had the hot idle issue which we were able to fix, without using the parts cannon! We engaged the services of an engine specialist after a mini specialist demonstrated a total lack of understanding. By replacing a loose valve seat the justa no longer misfires. At the same time I stopped the dreaded oil consumption that plagues the R56 engines through replacing valve guide seals and scraper rings, went from 1 litre per 800 miles to no oil consumption on a 125,000 engine. We will keep the car for a couple more years and then sell on, but will not return to either the BMW or Mini brand. Gen2 engines are a disgrace and BMWs behaviour is appalling with not addressing the many issues caused by putting into production an engine that was not production ready.