2008 E92 M3 intermittent misfire on multiple cylinders! 👎🏼

[M3Richard]

Apologies for this plea for help being my first post, but I'm struggling with the following:

I've currently got a 2008 e92 m3 with just under 76k miles and wondering if anyone else had similar issues.

I picked the car up in Wales and drove it all the way home to Northern Ireland with no issues what so ever. A few hundred miles later and having been left parked up in airport carpark over a weekend I was less than half a mile from home (50-60 mile trip) when I felt it hesitate before EML came on and it went into limp mode. I nursed it home as it began misfiring and got progressively worse. I turned it off and then attempted to start it again but it didnt. It was very smokey from exhaust.

I scanned it for faults, which showed misfiring on all but 2 cylinders code 2B47 - Misfiring cylinder 6, exhaust deteriorate permanent being one and the respective code for each of the other cylinders.

I had the car transported to an Indy BMW specialist who suspected it may be a crank shaft sensor and replaced it. The car was driven for another 150ish miles without issue before the same symptoms repeated, however was stopped sooner this time. Again the car was transported to mechanic who said it started first time and wasn't missing a beat from when it arrived with him.

Mechanic has changed nothing since and I now have the car home again. Having washed it during the week I turned it on and allowed it to warm up to temperature before turning off and leaving a few hours. I then tried the same again to see if the symptoms occurred again; they did... At 75 degress EML on and misfiring occurred. I knocked it off and on 30mins later to find it was running fine again.

I scanned codes later that evening to find the following:
2B35 - DME misfire with cut off cyl. 1
2B36 - DME misfire with cut off cyl. 2
2B37 - DME misfire with cut off cyl. 3
2B38 - DME misfire with cut off cyl. 4
2B39 - DME misfire with cut off cyl. 5
2B3A - DME misfire with cut off cyl. 6
2B3B - DME misfire with cut off cyl. 7
2B3C - DME misfire with cut off cyl. 8
2B41 - DME misifire with cutout several cylinders

There were a couple of historic faults and if believed may be of relevance I can post those too.

[bmwlover0725]

Originally Posted by M3Richard

Apologies for this plea for help being my first post, but I'm struggling with the following:

I've currently got a 2008 e92 m3 with just under 76k miles and wondering if anyone else had similar issues.

I picked the car up in Wales and drove it all the way home to Northern Ireland with no issues what so ever. A few hundred miles later and having been left parked up in airport carpark over a weekend I was less than half a mile from home (50-60 mile trip) when I felt it hesitate before EML came on and it went into limp mode. I nursed it home as it began misfiring and got progressively worse. I turned it off and then attempted to start it again but it didnt. It was very smokey from exhaust.

I scanned it for faults, which showed misfiring on all but 2 cylinders code 2B47 - Misfiring cylinder 6, exhaust deteriorate permanent being one and the respective code for each of the other cylinders.

I had the car transported to an Indy BMW specialist who suspected it may be a crank shaft sensor and replaced it. The car was driven for another 150ish miles without issue before the same symptoms repeated, however was stopped sooner this time. Again the car was transported to mechanic who said it started first time and wasn't missing a beat from when it arrived with him.

Mechanic has changed nothing since and I now have the car home again. Having washed it during the week I turned it on and allowed it to warm up to temperature before turning off and leaving a few hours. I then tried the same again to see if the symptoms occurred again; they did... At 75 degress EML on and misfiring occurred. I knocked it off and on 30mins later to find it was running fine again.

I scanned codes later that evening to find the following:
2B35 - DME misfire with cut off cyl. 1
2B36 - DME misfire with cut off cyl. 2
2B37 - DME misfire with cut off cyl. 3
2B38 - DME misfire with cut off cyl. 4
2B39 - DME misfire with cut off cyl. 5
2B3A - DME misfire with cut off cyl. 6
2B3B - DME misfire with cut off cyl. 7
2B3C - DME misfire with cut off cyl. 8
2B41 - DME misifire with cutout several cylinders

There were a couple of historic faults and if believed may be of relevance I can post those too.

Was the CPS that was replaced an OEM or aftermarket? I had an issue in my wife's X3 with an aftermarket one and ended up having to redo the job with a BMW sensor. Just a thought, but I know these cars can have issues with off brand sensors - especially when it comes to the crank.

[M3Richard]

Originally Posted by bmwlover0725

Was the CPS that was replaced an OEM or aftermarket? I had an issue in my wife's X3 with an aftermarket one and ended up having to redo the job with a BMW sensor. Just a thought, but I know these cars can have issues with off brand sensors - especially when it comes to the crank.

Hi,
My mechanic is ex BMW and now working as an indy. He's replaced it with a OEM. This is something worth remembering though, thanks.

[bmwlover0725]

Someone else may wanna jump in here, but here are my first thoughts:

Spark plugs
O2 (upstream)

Spark plugs are a long shot and don't typically fail like this, but if your O2's aren't working properly (weirder things have happened and not thrown codes) then you could be fouling the plugs.

You can start by checking one or two of the plugs to see how they look. If they're okay then I'd throw in at least one new upstream O2 to see if it works and then swap another one out if it does. That COULD fix your problem.

Misfires are complex, but DEFINITELY something to keep a close eye on. You don't want detonation.

Also - post the historic codes. They're worth taking a look at.

[M3Richard]

Revival of a never ending headache here with a bit of an update.

Throttle actuators were sent for repair and the ecu was unable to be tested by the company so put back in the car. The car again drive fine for a few miles then multiple misfires on all 8 cylinders.

The DME was then replaced at the stealership, where I was told that the misfire problem had been sorted. They were however recommending that I replaced the cats and o2 sensors due to potential damage from overfueling (ridiculous cost...not that the dme job was cheap). I refused to have this done and then drove less than 10 miles to have the EML come back on and for it to misfire again. However upon scanning it was now on just one cylinder; cylinder 6.
The dealership recovered the car and looked at it first thing on the Monday morning as this happened on Saturday afternoon. They again reiterated the cat and o2 sensors (despite no fault code) but were now telling me I needed a spark plug, injector, and coilpack on cylinder 6 (not exactly diagnosing the problem but replacing anything it could possibly be really).
I had this done by my indy and the car felt great until I was at the mot test centre and had just been called forward to my lane! EML with a lovely misfire on cylinder 6...
I scanned it again to find the following codes: P0356 and P138A. Having cleared these codes the car ran perfectly again and has done since. It is up for retest tomorrow and I'm hoping the same does not occur. Has anyone got any experience of these faults/symptoms?

A bit of an essay but trying to give a good a picture as possible.

Cheers.

[bvrider1]

76k...

If you plan on keeping the car. Ignition coils need to be replaced. Might as well do the spark plugs while you are at it.

Clear all codes and see if it persists.

Then I would go the O2 route. Post your findings.

[aus]

Do you have an X-Pipe?
I had all kinds of codes and cleared them and it drove fine.
Tightened up the header to X-pipe screws/bolts and it's been fine since. There was a tiny leak at the pipe collection point.
Otherwise, consider O2 sensors.
Good luck. Hate these stupid codes that don't tell you shit.
.

[Redd]

If it's misfiring on one cylinder, moving a plug /coil should also move the problem. Use that to troubleshoot.

If it's misfiring on all cylinders at the same time, it might be an intake or or O2 related issue. I would check the idle control valve and O2 sensors. I had a blockage at the ICV hose that gave me all cylinder misfire codes recently. These would happen intermittently also, like your problem.

One of the things I did was to put in an ELM327 OBD2 dongle and use Torque app to see what was happening with the air-fuel ratio during misfire. This helped me troubleshoot my ICV blockage.

[Pig Farmer]

I had the same series of codes when my car was approaching 50k miles. There were no specific codes pointing to any particular part/issue. The car started misfiring badly and would go into limp mode. I had already ordered a series a parts since I planned to perform preventive maintenance at 50k. I replaced the plugs, coils, LPF sensor, TAs, front O2 sensors, and header-to-xpipe gaskets. I don’t know exactly what was causing the misfires, but the issue was gone after replacing the aforementioned parts. Good luck.

[M3Richard]

So the car drive fine for the 20mile trip to the test centre. EML remained off and a new certificate issued.

Two miles later and the EML is on again with a very light misfire which comes and goes. Code again indicating cylinder 6.

With o2 sensors being mentioned in previous replies here, would it not be the case that a fault here would cause misfires along the whole bank as opposed to an individual cylinder?

As for swapping coil and plug to another cylinder to see if the problem follows, the coil, injector and plug where all replaced with oem parts at the same time.

Also worth pointing out that when stationary and under a bit of rev when the fault is present there is a blue tinge in the smoke from the exhaust (mainly from driver side pipes).

[roastbeef]

when was the last time the spark plugs were replaced?

[M3Richard]

Originally Posted by roastbeef

when was the last time the spark plugs were replaced?

A fortnight ago, along with the changes to cylinder 6

[rcracin]

With exhaust smoke, maybe you have a bad headgasket on that bank. Pull the plugs and inspect.