Ok so I've had this car for almost a year now, in that time ive constantly had trouble with a misfire in cylinder 2. While driving it goes into limp mode and reads a cylinder 2 and 3 misfire, after a few more miles the cylinder 3 clears up and leaves only #2. A dealer mechanic told me that since #3 and #2 are sister cylinders, #2 failure causes #3 failure. Anyways, I swapped out the coils and plugs for all oem parts, cleared up other misfires in all other cylinders at the time and nothing. Switched coils and plugs around to make sure the new ones arent bad, again nothing. No hard starts from cold and according to the torque app, fuel pressure is fine. I thought the failure was being cause by my faulty thermostat being stuck open and not letting the car warm up properly in the cold, but when i changed it nothing once again. The plugs dont look like they're fouled and when i turn off the car and turn it back on it comes out of limp mode and i have full power again, eventually the CEL turns off on its own after a few days but will come back on.
What could be causing this? I have a little less than 23k miles on it.


These are the codes I pulled with Carley that relate to the engine.

Fault Code: 002EFE Fault Explanation: Misfiring, several cylinders: recognized
Fault Code: 002F01 Fault Explanation: Cylinder 3 misfire: recognized
Fault Code: 002EE0 Fault Explanation: Misfiring, several cylinders: injection cut
Fault Code: 002EEA Fault Explanation: Misfiring, Cylinder 3 injector shutdown
Fault Code: 002F00 Fault Explanation: Misfiring, Cylinder 2: recognized
Fault Code: 002EE7 Fault Explanation: Misfiring, Cylinder 2: injection cut
Fault Code: 002EF7 Fault Explanation: Misfiring: injection cut Fault Code: 002EE2
Fault Explanation: Misfiring, several cylinders: exhaust harmful to startup Fault Code: 002EEC
Fault Explanation: Misfiring, cylinder 3: exhaust gas harmful to start operation
Fault Code: 002EE9 Fault Explanation: Misfiring, cylinder 2: exhaust gas harmful to start operation

These are other codes that i pulled but dont seem to be related but im adding them anyways incase they are:

Fault Code: 00A559 Fault Explanation: :KL30g f shutdown / KL.30g f shutdown / KL30g f Cutoff / Klemme30g f shutdown
Fault Code: 00E717 Fault Explanation: :Can embassy motor data / CAN message engine data / Embassy (KCAN: relative time, 328)
Fault Code: 00A900 Fault Explanation: :USB port: shutdown due to overloading

Fault Code: 00C587 Fault Explanation: :Falling asleep on the head unit is prevented / Falling asleep on the GW is prevented

Fault Code: 00D115 Fault Explanation: :Error CAN telegram timeout STAT GANG BACK

Fault Code: 00A8BA Fault Explanation: :Tail light broken right 1 -----fixed dont know why its still on
Fault Code: 00A8B3 Fault Explanation: :Direction indicators broken right rear-----fixed dont know why its still on

 

putting mileage aside, i would check three more things:
1- compression
2- coking on the valves
3- fuel injector

 

Forgot to mention I did a compression test, compression was like 150 and held it. I also looked at the Pistons with an endoscope and they had very little carbon build up, which leads me to believe that the valves should be fairly clean as well. I've ran some injector cleaner through the car a few times but I don't think if that has done anything, what would be the best way to check it?

 

if the compression across the board was similar, then that's a good start.

now, the only thing left on the table is injectors. if this were a non-S cooper, then the it is fairly easy to swap the injectors. if this is an S, you have to remove the intake manifold and look at the valves. naturally, the pistons will be cleaner because everything burns up unlike behind the valves where the carbon sticks and accumulate. while the manifold is out, swap the injectors around.

 

Like MiniTobe mentioned, I would first go for compression, too. But now that's eliminated, what about timing? Do you have a set of timing cam alignment tools? It's not that hard and intrusive to perform this check. I've a customer came to me with really rough idle and having multiple misfire engine codes. After I verified compression, I took out the valve cover, took out the spark plugs, insert kabob sticks to check piston height, turned the engine to find TDC, insert the flywheel locking pin, then put the alignment tools onto the cams. It turns out their motor has a skipped tooth on the intake cam by 8.12 degrees (estimated). After I reset their timing, things went back to great again. Maybe this is worth looking at.

 

I got the intake and injectors off, the valves are black but nothing caked on there . The injector does look darker than the other 3, it the second time me from the left. I dont think a timing issue would be the problem, it idles fine after I take it out of limp mode.

 

Good job getting them out. Now the million dollar question is, if ypu swap them, does the fault code move?

 

Replaced all the injectors with brand new ones and still misfiring. I double checked the compression to make sure it was still good and it is. I'm starting to run out of patience with this car.

 

did you confirm the timing as Yupetc mentioned?

Also, bad gas can cause issues to the point of no start. another buddy of mine had a bad ambient temp sensor. Run live data if you can and look at the values.

 

Wouldn't the timing being off cause all cylinders to misfire and throw a code?

 

typically, yes. But sometimes that's not the case. I recently bough a mini with 180 deg out of timing! the car starts right away, idles kind of fine, but once you drive, it starts cutting in intervals. compression was close to 200. The point is covering all the angles even the obvious ones. Also, vacuum leak can sometimes cause misfire. we want to zero in on all possible causes.

 

Here's some of the live data.
I'm going to have to wait for it to cool down to check on the timing

 

Did you run a compression test on all cylinders?

If not you need to know how #2 compression compares the compression in the other 3 cylinders.

Assuming the compression is ok, you might want to consider the crankshaft position sensor. If this sensor is acting up or in this case since the misfires are confined to just one cylinder maybe not the sensor but the ring with tabs that the sensor detects going by and from this checks the performance of each cylinder. If a cylinder on its power stroke does not contribute enough acceleration to the flywheel and if this happens over too many power strokes the engine controller will flag a misfire for this cylinder.

One or more tabs associated with cylinder 2 might be bent or in some other way compromised and as a result the crankshaft position sensor does not always get a good signal.

Or the ring might be loose. A sloppy clutch job can have the tabs bent if the flywheel isn't treated with care. Or if the flywheel had to be replaced and the ring had to be transferred from the old flywheel to the new one.

With an analog scope you can view the wave form generated by the sensor and perhaps see an anomaly in the wave form.

At 23K miles a bit early to suspect the O2 sensors.

If there are any knock sensors be sure they are properly secure.

 

I'm starting to think that I should just trade it in, it shouldn't be giving me any problems at this mileage

 

If you want to sell it cheap and junk, let me know, I'll tinker for years with these Mini Coopers for pure love of these cars.

 

Make me an offer!

 

Your vacuum is way too low. Should be pulling 16-20 for a healthy engine at idle.

 

isnt the n18 supposed to have low vacuum readings?

 

Define low. What is the specification?

 

This is what I found
https://www.northamericanmotoring.co...-question.html

 

OK FORGIVE ME AS IM WORKING ON MY OWN CAR. IM VERY NEW TO THIS. CAN you tell me what the piston height is suppose to be. Some are saying that all pistons are suppose to be the same height. Others are saying cylinder one is suppose to be Top Dead Center. I also have a timing tool. So to me my timing should be correct. However before I changed the valve seals the car didn't have an idle or shutoff problem. Only a valve seal leak and a rear engine seal leak. So I am honestly convinced it has something to do with the job I did when changing the valve seals. Maybe my compression is off because I didn't remove the head I did the compression method. My first original code after restarting the vehicle was 002B68 and that code has yet to leave even though I have already done the following.
Change PCV valve
Air mass sensor
vvt valve (rear of the intake)

There are moments where the car can idle for 2hrs and run completely smooth. Then other times it has the hard start, the rough idling and periodically shutting off.