2010 mini base n12 starts perfectly and runs like a million until it gets fully warmed up, then runs like a bucket of bolts. Get code p0302. If i unplug a cam sensor (either one) it idles perfectly and drives ok. I have pulled the vanos sensors and they are perfectly clean, same with the cam sensors. Granted i get an engine light with the cam sensor unplugged but at least i can drive the car. Has anyone had this issue and what can be done to fix this. Is running the car with a cam sensor unplugged going to hurt anything.

 

You need to have the car looked at by a qualified tech.

Have you put spark plugs in the car yet? They fail around 45-60k (but MINI rates them for 100k), if you haven't replaced them start there regardless.

VANOS solenoids can have internal problems that you can't see, only way to quickly diagnose is with a scan tool.

You may also be having timing problems, which requires special tools to diagnose.

 

what was the fix to this issue? VANOS solenoids?

 

clean or replace both non return valves! Also check solenoids they might be dirty again. How often you change oil? Vanos sometimes incorrectly installed during replacement. You should check timing. You saying that you are running on three cylinders. Do you know why? What is the compression second cylinder and on all other cylinders? If compression is even on all of them that its ignition or sparks or coils or wiring. If cylinder two is low on compression you need leak down test to figure out what is damaged. Let me know with what you came up. PS. Don't suggest you to unplug solenoids while car is running.

 

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 results in an eventual destroyed 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 valves lift at idle is very shallow and this results in the valve with the loose seat not sealing resulting in 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.

 

Im fighting this same issue, how does stroke length of the valve change the seat of the valve seat?

 

With variable valve lift the valve stroke at idle is microns of movement and when combined with a loose valve seat results in the loss of compression due to the valve and seat not sealing. You will find that the inlet port of the affect cylinder is hotter than the other three. The problem isn't variable valve lift, that's how the engine should operate, the issue is that you have a loose valve seat due to other Prince engine issues - the engine overheats due to the sheer amount of oil burned which causes lean out and a rise in combustion temperature. The head is aluminium while the seats are steel so expand a different temperatures, coupled by the fact that the seats are like the rest of the engine cheap and not substantial enough to ride out the temperatures, resulting in them dropping out of their seats and so on. These engines are a real piece of rubbish which BMW is fully aware of. You have to replace the offending seat.

 

I understand the system, but what causes it not to seat at minimum stroke vs on throttle/longer stroke. I would think with less lift the seat has less place to go

 

I wouldn't worry about the theory, you need to get the head off and in to an engine specialist to replace the offending valve seat(s) otherwise you are looking at a full set of pistons plus head repair beyond a seat replacement. Note the cylinder the is miss firing as the engine specialist will need to rip out the trash seats and put in some real/robust seats. While the head is off, pull the pistons, dump the rings that BMW picked and put in a 5 ring set .i.e., a 3 piece oil control ring plus a new scraper and compression ring. You will need to deglaze the bores, this will fix oil consumption issues and provide you with a refreshed engine. I did this exact act around 35,000 limes ago and the little bugger is running sweat - I in tend to run it to the 200,000 and then run it off a cliff for good measure

 

I wanted to follow up on this. Mickey was %100 correct. After i exhausted every option i had including doing a running compression test while it was acting up ( it was 100 psi lower) , then removing the cam sensor and seeing compression return. pulled the head, replaced it with rebuilt head with better seats. Problem solved.