Hey Guys,
Got kind of an odd issue with a 2010 with the N12 and was wondering if anyone else has experienced this issue. I have searched the forums extensively for anyone with a similar issue and have not been able to find anyone with this issue or anything like it. I have exhaustively attempted to repair this issue and to no avail and am look for any input on the matter at this point. The car had been sitting for a few months when we pulled it out of storage at that point it had misfires on various cylinders and a pretty worn out timing chain. I replaced the timing chains and found a few collapsed lifter and due to the fact the vehicle has 150k on it decided to do a head gasket and valve job while i was in there. The only issue i am still chasing that this point is a misfire on cylinder 1 but only once the vehicle is warm (90 degrees C or hotter). Here is the odd part though, if i unplug any of the cam position sensors, vanos solenoids or eccentric shaft sensor the misfire goes away and the vehicle runs great. Also, if i unplug ignition coil 4, the misfire on cylinder 1 goes away if i unplug coil 2 or 3 the misfire on cylinder 1 is still present. Here are the parts ive swapped or replaced.

-Both Vanos Solenoids
-Both Vanos Adjusters
-Both cam postion sensors
-Crank Sensor
-Engine harness
-Coils and plugs
-MAF
-DME
-Eccentric shaft, motor and sensor

In addition i have done both a hot and cold compression and leakdown test which provided good results. I have also updated the vehicle to the latest I-Level. Im running out of ideas on what could be causing this and am hoping someone here has had a similar issue or can point me in a new direction. Thank you!

 

My first guess would be a possible bad ground connection for the coils. I'd remove the nut here (red circle) and clean the connection with some scotch brite.

 

Hey Lou thanks for the reply, I did verify that the ground is not the issue via a resistance check as well as adding an addition ground from that nut directly to the battery.

 

Hi, how did you do with this issue? I have had 3 mini R56 with this issue in the past year. Ended up parting the last 2, but now another one. Its getting old. Compression, leak down all good, swapped EVERY top end part with known good oem parts from another car. Typical symptoms are misfiring at idle once worn, but deactivating the VVT system via unplugged connector solves the misfire, but obviously causes its own issues.

 

Unfortunately , I am still working on this.... I have found quite a few people now who have the same unresolved issue with the same concern. I have swapped just about everything i can think of other then the camshafts so i might try that next. I find it so hard to believe, being that there are so many cases of this, that no one has found the solution.

 

During cold start fueling is open loop. Meaning injection is predetermined and VVT is locked until engine warms. Sounds like the issues are VVT related. Check VVT solenoid screens for blockage first. Some have luck cleaning them. If cleaning/replacement doesn't work you may have a bad vanos unit. You can also view vanos target angle vs actual via INPA or another tool.

 

Lou,
Both Vanos solenoids were replaced as well as Vanos units. The eccentric shaft and sensor where replaced as well as the valvetronic motor swapped. I think its interesting that it only affects cylinder 1 and in every case Ive seen it happens at 90 Degrees C. The one thing i noticed which i have not seen in any other case was that if you unplugged ignition coil 4 while its at 90c and misfiring, the misfire goes away on cylinder 1 and then only misses on cylinder 4. If you unplug coils 2 or 3, you then get a miss on both cylinders. I have monitored the Vanos target and actual and right at the time it starts misfiring the vanos target and actual start to fluctuate drastically.The Target value is always achieved but from some reason the Target fluctuates all over the place. Being that it only happens right at the time of misfire its hard to determine whether its adjusting due to the fact that the car is misfiring or if it in fact is trying to move the cams for some unknown reason.

 

Hmmm... warm up and warm are separate tables for vanos. Possibly low oil pressure with 150k miles. Maybe try 5W40. Also have you checked continuity to ground on the ground wires for the ecu? Maybe check for corrosion on the contacts of the DME master relay. Just spitballing ideas here.

 

Lou, same scenario here, I have had 2 of these cars with this issue. I have replaced EVERYTHING VVT, VANOS, ECCENTRIC, etc., I have monitored the angles but honestly cannot remember the results. I will check some of this for comparison on a mini that is acting up on me in a similar way hopefully in the next few days, thanks for the tips

 

Lou, Harness has been replaced as well as the DME. Resistance from DME to ground is good and additional grounding has been added to both the DME and engine to verify. I think its interesting how many cases ive found where people are reporting the same issue at 90 degrees C but nobody has a resolution for it. Regarding oil pressures, I cant figure out how that would cause a miss on just cylinder one i did however verify that oil pressure is within spec. In fact i cant figure out how anything relating to timing could cause this being that if it was Vanos or VVT related youd think it would affect that entire camshaft not just one cylinder.

 

it would seem to me that at 90 degrees the DME starts using sensors to make adjustments and is getting bad information from someone, I just cant seem to find the one causing the problem.

 

Hi,
Solved this issue on two R56 by DME replace.Both cars run perfect on cold, but after warming time fail and get misfire on cylinder 3.Solution was to buy a used DME with same hw number and clone the car DME .Easy job.For you I recomand to buy a start kit, price around 100$ for N12 engine or 250$ for N14engine on ebay.
Best one is to call a local tuner , for sure he can clone your DME,is one hour job,depend on what kind of tool it have for cloning.

 

The DME has been replaced.

 

I've been struggling with this issue on my n12 r55 and finally figured mine out I hope. I've been swapping vanos, I actually have 3 new ones 2 china cheapos and a dorman along with the original. I swapped the dorman out for the original which was giving my the p0015 code and misfire cylinder 1. The dorman and others just gave me the misfire cylinder 1 and no p0015, the original is the 1 with removable screen older style. So today I put the original in and ran with it disconnected once it started acting up. After I got off I reconnected it, cleared codes, ran vanos adaptions still the miss so I went to the store and grabbed a bottle of Lucas oil stabilizer(the thicker stuff) and put half or so of the bottle in and bam no more p0015 or mis with original vanos in. So that makes me believe oil pressure is to low at idle with 5w30 when it's hot and need to run a little thicker oil or could be the not genuine oil filter I'm having to run this oil change.

 

@eMpowerAuto

Did you find a solution? I have the same issue and it is driving me crazy.

Found that if I turn on the AC on full causing the thermostat to open and the coolant temp goes below 90, misfire on #1 goes away.

 

I have misfire on No. 2 after warm at idle. After swapping spark plugs and coils, stayed on No. 2. Compression /leak down test good. New valve stem seals and recently ground seats. I'm gonna try some thicker oil. Any other quick fixes? Vanos parts have been taken out and cleaned. I'll check for good ground to center nut. Gotta get rid of this damned CEL.

 

I finally rebuilt the entire engine. Head rebuilt, oversized pistons, new bearings, new sensors, new timing chain, water pump, thermostat sensor, etc. and misfire on #1 returned. Makes me think I have a computer problem. New computer on order... we will see.

 

New DME did not work. Bought another used engine and swapped it out with all the original sensors. Problem solved. Don’t know what was wrong with original long block.

 

Curious if anyone ever resolved this. I’ve been having the same problem: misfire cylinder 1 only at idle and only when warm. Mine also will misfire when warm and coasting down a hill with no load on the engine.

Replaced plugs, coils, and VANOS solenoids recently trying to fix the issue. Added Lucas oil stabilizer as well to see if that fixed it.

I’m stumped.

 

IT is your cylinder head valve seats.

 

It’s the intake valve seats. Any slight drop will cause issues, I finally solved this issue on my N12, valve seats replaced and problem went away. Thank you Tomrad for helping me out!

 

It’s the intake valve seats. Any slight drop will cause issues, I finally solved this issue on my N12, valve seats replaced and problem went away. Thank you Tomrad for helping me out!

 

I am glad you solved your problem

 

Hi, maybe this is an old thread but was the compression good with the bad seats! Thanks.

 

Yes the compression was still good because the drop of the valve seat would be really small, my compression test did not show any problems.