[dieselwagon]

Hi all,

Long time BMW owner and currently have an F31 328d xDrive wagon. It hasn't been the best relationship in the last few years, but I wont hold a few things against it - such as an exploding accessory belt or the expensive oil leak that needed to get fixed.

No, what is driving me up the wall at the moment is the dreaded "drivetrain malfunction" error. However, the situation is the weirdest and I am really looking to see if anyone has any ideas on where to look?

I am in California and its a bit hot at the moment. Engine is cold - everything is fine and can drive off without an error or problem. Could be 5, 50 or 200 miles - no issues and runs perfectly.

However, if you come back within the hour, the engine is nicely heat soaked and the outside temperature is 90F or more, I get the dreaded "drivetrain malfunction". Can drive the car, but obviously its pulling a lot of the power and its a nightmare.

Currently getting two codes - 282C00 and 27F100. Its been to a local BMW dealer who completely failed to replicate the problem, twice! But they claim to have checked the EGR and its operation, as well as the car as a whole. They reported 'no fault found'. I have Bimmerlink as well as an old laptop with ISTA and I can see that the fault is in the diesel ECU and clearing the fault it will run perfectly. Reading the faults seem to indicate that the EGR isnt working correctly or that there is a boost leak.

With Bimmerlink, I was able to see some of the data for the EGR and it does seem to be operating (well the ECU thinks its operating) and while there isnt much to check the boost, it is generating boost and it seems fine.

I replaced one of the charge pipes to the intercooler yesterday in a hope that it might seal better, but nope, same issue today. This is driving me mad!

Any ideas? EGR and EGR cooler were replaced as part of the recall back in 2023 and are still under the 2 year warranty from BMW, but with the dealer and Bimmerlink suggesting its fine, I think it might be related to a boost leak. I got one of those cheap smoke generators and tried to see if there were any obvious leaks, but to no avail.

Before I start throwing parts at it, does anyone have any ideas on what might be triggering these codes? Happy to try pretty much anything at the moment. I'll try and get it booked into a local independent BMW place, but they are booked out for weeks. Willing to try pretty much anything to make this damn issue go away!

Oh, and car has 143k miles on it. DPF is working well (checked it) and soot measurements from the ECU show its running well. Though these codes arent related to that.

Sorry for the long post, but please dont make me go and buy a boring Japanese car!!!

[n00bkiller944]

Swirl Flaps? Carbon build up issues? Did you have the EGR replaced under the recall?

[dieselwagon]

Yeah, EGR and EGR cooler replaced in 2023 under the warranty. Seems to be operating as required, but of course that might not be the case.

It’s got 143k on it, so could well have carbon build up. I can do some relatively straightforward stuff, but certainly wouldnt call myself good with a wrench - is taking off the intake and cleaning the swirl flaps etc relatively easy? Or is it a professional job only?

[FaRKle!]

If you have ISTA, what does the freeze frame data show? ISTA tells you what the conditions need to be to trigger the code, and records the vehicle operating state when the code is triggered, even if the code isn't active anymore. I think you'll find a lot of what you're looking for in there.

[dieselwagon]

Excellent - thanks. I can pretty much make it happen on demand at the moment, so I can trigger it and then get ISTA plugged in.

I will admit that I do find ISTA pretty tough to get around, other than the basic check for errors bit. Where would I find the freeze frame data part? I got ISTA as a download and I am pretty sure its super out of date, so any general guidance on where to look would be great.

[FaRKle!]

Originally Posted by dieselwagon

Where would I find the freeze frame data part? I got ISTA as a download and I am pretty sure its super out of date, so any general guidance on where to look would be great.

Just double click on the code after the initial vehicle scan is done, then in the pop up window it says what the code is (and there are tabs in that window) to show the freeze frame data.

[dieselwagon]

There is nothing worse than someone asking a question on a forum and not posting a follow up - positive or negative!

It’s been a lot cooler here recently I and not been using the car as much, so haven’t had the chance to trigger the error and run through ISTA. However, today it triggered again on my drive, so time to get the laptop out!

I ran through the tests that ITSA recommended and I wonder what my neighbors thought! Rev to 3000 RPM and then idle and then nearly 4000 for a minute - well thats what it felt like. Anyway, everything passed including the EGR, which was the one I was dubious about given the 282C00 error code description.

The last thing that it wanted to check was the hot wire mass air flow meter, and I was only a little out of range, but it seem to be enough. I think it was saying that +/- 6% was OK, but I was running at 12% and 25% at one rev range. It seems strange that the error might be the MAF, given that the car seems to run right most of the time. When the limp mode kicks in, a quick stop and start again and its gone, so really not sure why it would be so variable - I thought it was a case of working or not, but I guess that it can go out on weird readings, which might cause a problem.

Ordered a new one for delivery on Wednesday. FCP Euro had an offer on for an OEM Bosch part, so let’s see if this fixes it. I have previously cleaned it, but I guess it’s going weird and hence the problem.

Oh, and have replaced the charge pipes just in case, and as part of the ISTA tests, it checks the pressure and temp difference across the intercooler - all passed. Lets see if its the MAF sensor. But I will keep everyone posted.

This is a weird one.

[FaRKle!]

Do you have an aftermarket intake or stock? MAF readings with aftermarket intakes are always off...

[dieselwagon]

Originally Posted by FaRKle!

Do you have an aftermarket intake or stock? MAF readings with aftermarket intakes are always off...

Nah, totally stock. Tempted by an aftermarket one, but I am in California and if I need to sell it, I am stuck. Though I know I can reverse it.

I threw a couple of charge pipes at it to see if was a boost leak, but I did inspect the old ones and they were fine.

So far its running great though. I need to get ISTA plugged in and get it to run through the tests again, but had a 90 mile drive this morning and its way more economical! The problem only affects it when its hot, which it wasnt, but so far its looking very positive.

Anyone know why a MAF might go weird like this? I get it when a sensor fails, but failing a bit? Thats not something that I have come across before.