[frydog59]

New BMW owner here. I am mechanically inclined and before now did most work on my vehicles myself. While waiting to get out of the parking lot following an airshow, ( idling and creeping for the better part of 40 minutes), I noticed a slight "jerk" occasionally. When we finally got some room, I got on her a bit, she jerked a few time and then I got a drive train malfunction warning and a check engine light.. As soon as I could I pulled over and shut her off. The warning and light went away but I still feel a little jerk now and then. Just got it back from the dealer after getting the TPM module replaced. Anyone have this experience. Hoping plug or coil.

[hogwldfltr]

Did you ask the dealer? If so what did they say?

[frydog59]

Not yet. Happened on a Saturday and no one was open. Just wanted to get a feel for what I might be looking at.

[najnad]

how many miles on the plugs/coils? how hot did the engine get crawling along like that?

[TheCoolX3]

Id look at your plugs, could have got real warm and 40 minutes in prime carbon build up range could cause an issue like yours.

[frydog59]

Under 250. No sure on plugs/coils. I think we might have put regular gas in. First premium vehicle. Added octane booster and filled up with premium and misfire seems to be gone. Still get malfunction message when I get on it. Could clearing code stop the message if the misfire is gone.

[najnad]

Yes, code clearing should get rid of the message if the misfire is gone (and if the misfire was the only reason it came on).

Regular gas sounds like the main problem, but I would consider replacing at least the plugs if you have no idea how many miles are on them...wouldnt surprise me if they are the originals.

[frydog59]

Thanks for the replies. I know that when I test drove it, and once or twice since, when I romped on her, she got and went with no code or warning
That only happened after the misfire. Going to a diagnostic for sure.

[najnad]

I know when I had a bad plug and getting drivetrain malfunction and slightly rough idle the codes didnt say it was the sparkplug, my mechanic had to do the old school process of removing one plug at a time with a known good plug to figure out where the problem was.

[frydog59]

Well, finally got around to getting it some where to have the code read. It said number 4 misfire. Hoping that it was either a spark plug or a coil, and not an injector I switched the coil on number 4 with the coil on number one and then I was going to drive it and see if it followed the coil. Even better since I did that it hasn't missed one and it hasn't given me the drivetrain malfunction warning either. I've driven in all conditions under all different loads, even romped on it a couple of times. I can only conclude from that, that either the coil wasn't seated properly which really doesn't make any sense because I think it would have been doing that from the get-go, or the connector itself wasn't making good contact. Maybe when they detailed they blasted a lot of water under there and it got inside that connector maybe corroded a little bit. Good news is problem solved

[Fast400]

At least it was simple stuff! 90% of the time the "Drivetrain Malfunction" is caused by the simple things you diagnosed. I made a whole video on the topic twice because apparently sooo many people have this issue at some point

[najnad]

Originally Posted by najnad

I know when I had a bad plug and getting drivetrain malfunction and slightly rough idle the codes didnt say it was the sparkplug, my mechanic had to do the old school process of removing one plug at a time with a known good plug to figure out where the problem was.

And now, another spark plug has gone bad...was using Bosch, going back to OEM. The plug (both times) the ceramic part became loose and only really acted up when hot and under load, but then it would not give consistent error codes, so my mechanic was chasing codes until the only thing left to check was coils and plugs.