[slonkijippie]

2018 M240i X-Drive ZF8

Car has been developing some issues, noticed it first doing WOT on sport mode. The car will go through gear 1-2-3 as it should, when it approaches redline in 3rd gear it won't upshift to 4th on its own. It hits the limiter and then goes into drivetrain malfunction mode. It has misfires after this, vibrates and runs rough, probably not on all cylinders. Get flashing check engine light and then a lasting check engine.

Error codes:

120408 - Charging pressure control: Switch-off as consequential reaction.
140001 - Combustion misfires, several cylinders: Fuel injection is switched off.
140010 - Combustion misfires, several cylinders: detected.
140601 - Combustion misfire, cylinder 6: Fuel injection is switched off.
140610 - Combustion misfire, cylinder 6: detected



Took it into a shop and they replaced all 6 sparkplugs, the car did not misfire instantly upon startup anymore. I took the car back and went out for a test-drive immediately to make sure it was fixed, it was not. Exact same issue. Does not upshift to 4th gear in sport mode (and trans), just hangs at rev limiter, then drivetrain malfunction and misfires and does not run on all cylinders. No check engine light, did not manage to scan the codes the second time since I just dropped it off again.


Anyone know what the issue could be? The car is back at the workshop but I'm curious to know what it could be.

I would guess Ignition coil, fuel injector or fuel pump? I still think it's strange that it won't upshift on its own if any of those above would be the issue.

[freakystyly]

It really sounds like an automatic transmission problem more than an engine problem. Maybe take it in to someone who knows ZF transmissions?

Is the car modded with any kind of transmission tune or engine tune?

[slonkijippie]

Originally Posted by freakystyly

It really sounds like an automatic transmission problem more than an engine problem. Maybe take it in to someone who knows ZF transmissions?

Is the car modded with any kind of transmission tune or engine tune?

Car is completely stock.

The strange this is that the trans seem to work as normal in every other way except than this specific scenario. Also strange that it goes the driveline malfunction and that it then misfires permanently after it hits the rev limiter.

[Kernel Kurtz]

I agree with freakystyly it sounds more like a transmission problem. Will it shift into fourth if you do it manually?

[slonkijippie]

Originally Posted by Kernel Kurtz

I agree with freakystyly it sounds more like a transmission problem. Will it shift into fourth if you do it manually?

Yeah the trans works normally if i do it manually

[Kernel Kurtz]

Originally Posted by slonkijippie

Yeah the trans works normally if i do it manually

And no engine issues then? If that is the case IMO it is the extended bouncing off the limiter that causes the CEL, and the lack of shifting is the root cause. I'd guess a problem with the Transmission Control Unit, but I'm far from an expert. Being in Germany you should have no shortage of experts though. Good luck and let us know when you get it figured out.

[JMcLellan]

Originally Posted by Kernel Kurtz

And no engine issues then? If that is the case IMO it is the extended bouncing off the limiter that causes the CEL, and the lack of shifting is the root cause. I'd guess a problem with the Transmission Control Unit, but I'm far from an expert. Being in Germany you should have no shortage of experts though. Good luck and let us know when you get it figured out.

100% agree with this logic. Doesn't sound like a mechanical problem since it does shift into 4th manually. One thought I had was that if you were ever planning on tuning the trans with XHP you could install that and see if there are any codes to be read (not sure if the CEL codes you have access to now also read TCU specific readings?). Then you could also play around with RPM shift points to see if you could change the behavior. Something I would consider in the event I couldn't find a place I trust to properly diagnose the issue. And, the XHP trans tune is pretty sweet so why not??

[slonkijippie]

Originally Posted by Kernel Kurtz

And no engine issues then? If that is the case IMO it is the extended bouncing off the limiter that causes the CEL, and the lack of shifting is the root cause. I'd guess a problem with the Transmission Control Unit, but I'm far from an expert. Being in Germany you should have no shortage of experts though. Good luck and let us know when you get it figured out.

Surely you can bounce on the limiter without a drivetrain malfunction into misfires and barely drivable car?

[freakystyly]

You're right, there should be some failsafes built in to the engine programming that manual transmission cars would have. Under normal working operation the automatic never sees the real redline though. The engine problems are a symptom and not the cause.

It's above my pay grade to figure that one out.

[M3SQRD]

Definitely sounds like an automatic gearbox problem; however, with how complex BMW makes their cars and all of the different modules that have to communicate, it could almost be anything causing your 3-4 shifting issue! Good luck !

[Kernel Kurtz]

Originally Posted by slonkijippie

Surely you can bounce on the limiter without a drivetrain malfunction into misfires and barely drivable car?

One would think so. Not sure how long it is safe to keep it there though.

Like I said, I'm not an expert, I'm just guessing which is the more logical cause and effect. Either the CEL is causing a transmission problem, or a transmission problem is causing the CEL. Or I suppose they could both be completely unrelated, which would probably be the least desirable outcome.

[Amplifiedcreations-f30]

Were you able to solve this? I have the exact same issue only as of today it’s now misfiring all the time (before was only in sport mode at WOT)

Thanks

[slonkijippie]

Adding some info here incase someone finds this post later.

I never got to figure out what the issue was.

What happened after my initial post was that the car sat at this first workshop for 4 weeks with no one touching it, they said the car would not start.

I demanded the car to be towed to a BMW dealership that knew what they were doing. The BMW techs looked at it and figured out why it would not start, Cylinder 6 was full of oil. They could spin the engine by hand backwards until it stopped, then forward again until it stopped. The cylinder could not compress the oil in the cylinder, thats why it would not turn over.

They pumped out all the oil in the cylinder, and then the car would start up and bellow out tons of smoke from all the oil that burned off. After a while sat at idle, it would stop smoking and behave normally. The BMW techs said some PVC part was the problem, would not say specifically what part.

They replaced that part on a friday, the car then sat over the weekend, on tuesday they had to move the car. When they started up the car it spewed out tons of smoke, once again.

After this the BMW dealership ruled out the engine in the car and said it needed to be replaced.

I still had warranty left on the car from where I bought it, and this whole repair process had been going on for 3 months and the car was still not fixed. After alot of back and forth I demanded to have the car refunded, and was eventually granted this and got my money back. Never got to figure out the transmission issue either.

Still have the car in my BMW app and it's still sitting at the dealership, probably still broken.

[MarcoZandrini]

The first code translates to: t is fault normally sets as the result of a problem with another component of the engine management system.

Op: did the shop scan the transmission control unit?