Sputters/power cut offs at higher rpms

[JoepM5]

Hi all,

I’m new here and recently got my 2012 M5 which I absolutely adore. In 2 months put 5k kms on it including a round trip to Austria (from Amsterdam) and the car is brilliant.

However, I notice one thing and that is that the car has short (< 1 sec) but quite heavy/intense power cut-offs/sputters when getting above 4.5/5k rpm in at least 3rd/4th gear. It happens both full throttle but also when revving it more slowly/gently. No fault codes or ECL light comes up. Otherwise the car runs faultlessy. Tried different fuels/RONs without any luck. The car is fully standard, no mods whatsoever

Anyone any idea what this can be?

Thanks a lot!

Best,
Joep

[Blaxwil]

I had this exact issue. It turned out to be the ECU connections were not snug and tight. If you've had some engine work lately whereas the ECU's were disconnected, I bet that's your issue.

[INFURNO]

When were the coils and plugs last done? Sounds like a misfire.

[JoepM5]

Thanks a lot for your input guys!

Blaxwil : no recent work on the engine done with disconnecting the ECU's but will check for sure. What is the location of the ECU's? They are on both sides of the engine underneath the top plastic cover?

INFURNO : I'm not sure when the spark plugs/coils were exactly done for the last time but would assume that a misfire would always result in error codes/messages?

Thanks!

[Blaxwil]

Originally Posted by JoepM5

Thanks a lot for your input guys!

Blaxwil : no recent work on the engine done with disconnecting the ECU's but will check for sure. What is the location of the ECU's? They are on both sides of the engine underneath the top plastic cover?

INFURNO : I'm not sure when the spark plugs/coils were exactly done for the last time but would assume that a misfire would always result in error codes/messages?

Thanks!

Correct. Pull the plastic cover off (carefully so not to break the clips). There are 2 ECU's located to your left and right. Both have either 4 or 5 connectors. Make sure all the connectors are fully seated. Also make sure all screws are tight. It's amazing that this was my problem. Send me a PM and I'll send you a video to see if we had the same issue.

[JoepM5]

Hi Blaxwil, super - many thanks!

Somehow as a new member I need to make 4 post replies before being able to send you a PM. Will try to make that.

[vafan13]

Originally Posted by JoepM5

INFURNO : I'm not sure when the spark plugs/coils were exactly done for the last time but would assume that a misfire would always result in error codes/messages?

Thanks!

I think whether it actually throws a DTM depends on the rate of misfires, which can be touchy. You could try doing a few 3rd gear pulls in quick succession. It's also possible that it still stores misfire codes as non-permanent errors or warnings if it doesn't hit that threshold, which one could see with a code reader or Bimmerlink. That I don't know, though. I've had two instances of misfires. First time it threw DTM on a single WOT acceleration (from what I could tell). I replaced just that coil and was good. This summer it was more subtle and it didn't throw the code until I did successive pulls, which I did because I noticed some hesitation in high RPMs on the first one. I had new plugs and coils on hand so just did them all at that point.

Honestly, if you have a 2012 and no way to know when plugs and coils were changed, it isn't a bad idea to change them, anyways. This car is hard on both.

[JoepM5]

Originally Posted by Blaxwil

Correct. Pull the plastic cover off (carefully so not to break the clips). There are 2 ECU's located to your left and right. Both have either 4 or 5 connectors. Make sure all the connectors are fully seated. Also make sure all screws are tight. It's amazing that this was my problem. Send me a PM and I'll send you a video to see if we had the same issue.

Hi Blaxwil, your PM inbox is full so I cant reply to your message

vafan13: agree that it isn't a bad idea to replace them anyway, just not sure whether it fixes it

[INFURNO]

You can do some damage if it's a miss. I wouldn't push it until this is resolved. You'll have to pull and reseat computers when you do your plugs. Make sure to gap them. Oem or not. Don't trust it until you've checked. Once you're done you can log the service and rest easy.

It's not a hard project. But make sure you properly connect the new coils. It's kind of hard to tell if it has a solid lock.

[lucid21]

Could be fuel delivery issues. How many fuel pumps does this car have (I don't know)? If it has two and one goes bad, the other one will have issues keeping up under high rpm and load.

[lucid21]

Originally Posted by vafan13

I think whether it actually throws a DTM depends on the rate of misfires, which can be touchy. You could try doing a few 3rd gear pulls in quick succession. It's also possible that it still stores misfire codes as non-permanent errors or warnings if it doesn't hit that threshold, which one could see with a code reader or Bimmerlink. That I don't know, though. I've had two instances of misfires. First time it threw DTM on a single WOT acceleration (from what I could tell). I replaced just that coil and was good. This summer it was more subtle and it didn't throw the code until I did successive pulls, which I did because I noticed some hesitation in high RPMs on the first one. I had new plugs and coils on hand so just did them all at that point.

Honestly, if you have a 2012 and no way to know when plugs and coils were changed, it isn't a bad idea to change them, anyways. This car is hard on both.

I would think that if the power cuts off as severely as the OP describes, there would be a code thrown. That said, if the owner doesn't know the maintenance history, it is indeed a good idea to do coils and plugs regardless.

[vafan13]

Originally Posted by lucid21

I would think that if the power cuts off as severely as the OP describes, there would be a code thrown. That said, if the owner doesn't know the maintenance history, it is indeed a good idea to do coils and plugs regardless.

I would have thought so as well, but I'd say the same about power being cut that hard due to lack of fuel. I also thought that his comment on it happening at high RPMs regardless of being WOT or gradual acceleration might be evidence against fuel pumps (or at least more in favor of coils/plugs). I still think doing a few pulls in quick succession might help trip the DTM.

OP: as a clarification, when you say no codes or CEL, do you mean nothing showing on the status screen of the car, or did you use a code scanner?


P.S. I believe it's one LPFP and two HPFPs.

[JoepM5]

Hi all,

Thanks a lot for your replies.

Quick updates:
- the sputtering/power cuts have become more severe over the past days, now also with lower revs and even gentle (25% throttle or so) acceleration it starts to sputter significantly. When cruising and very gentle acceleration (10-20% throttle) it is 100% fine, no shaking or whatever
- I now get the Drive Train Malfunction when I trigger the heavy sputtering but no ECL and once I shut the car off, the DTM disappears
- I used a code scanner and nothing really popped-up (some non-items around electrical seats, etc.) except for 180001 Catalytic Converter: Efficiency below the limit value. When deleting codes, this one wouldn't delete.
- In the last days, the car also dies down within 3 seconds or so after firing it up for a first time both with a cold and warm engine (~15 mins after I shut it down after a longer drive). If I try to fire it up for a second or third time it runs normally
- Checked ECU connections, they are fine
- Talked to the BMW M specialist nearby on the phone and he is confident it isn't a misfiring problem (since the car runs perfectly fine after it sputtered, it doesn't shut off cylinders) and he suspects the Low Pressure Fuel Pump (that is inside the gas tank).

Will bring the car in likely next week (this week the shop was fully booked) to get it fixed and get spark-plugs/coils done preventivly.

However, eager to hear what you guys think whether it might be the LPFP?

A fuel issue would at least be in line with my other BMW M - wanted to take out my E30 M3 for a last spin before the winter today and a fuel hose
had gone bad. Probably already leaked a bit before (smelled some fuel in the garage) but now fuel literally was flying out under pressure onto the engine. Luckily the engine was cold...

Thanks a lot for the support/ideas - much appreciated!

Best,
Joep

[M5_Raz]

Originally Posted by JoepM5

Hi all,

Thanks a lot for your replies.

Quick updates:
- the sputtering/power cuts have become more severe over the past days, now also with lower revs and even gentle (25% throttle or so) acceleration it starts to sputter significantly. When cruising and very gentle acceleration (10-20% throttle) it is 100% fine, no shaking or whatever
- I now get the Drive Train Malfunction when I trigger the heavy sputtering but no ECL and once I shut the car off, the DTM disappears
- I used a code scanner and nothing really popped-up (some non-items around electrical seats, etc.) except for 180001 Catalytic Converter: Efficiency below the limit value. When deleting codes, this one wouldn't delete.
- In the last days, the car also dies down within 3 seconds or so after firing it up for a first time both with a cold and warm engine (~15 mins after I shut it down after a longer drive). If I try to fire it up for a second or third time it runs normally
- Checked ECU connections, they are fine
- Talked to the BMW M specialist nearby on the phone and he is confident it isn't a misfiring problem (since the car runs perfectly fine after it sputtered, it doesn't shut off cylinders) and he suspects the Low Pressure Fuel Pump (that is inside the gas tank).

Will bring the car in likely next week (this week the shop was fully booked) to get it fixed and get spark-plugs/coils done preventivly.

However, eager to hear what you guys think whether it might be the LPFP?

A fuel issue would at least be in line with my other BMW M - wanted to take out my E30 M3 for a last spin before the winter today and a fuel hose
had gone bad. Probably already leaked a bit before (smelled some fuel in the garage) but now fuel literally was flying out under pressure onto the engine. Luckily the engine was cold...

Thanks a lot for the support/ideas - much appreciated!

Best,
Joep

Dude, why are you driving it with such a big problem?! Lol

You need a real shop to scan it, many codes don't show up on regular scanners. With the cats throwing a code, it could be the O2 sensors. They're pretty easy to replace yourself.

[vafan13]

O2 sensors are certainly a possibility with the symptoms and that code, though if it's now having issues at startup...I'm not sure sensors are used for the first 30s or so. I might be making that up or confusing it with something else, though.. At this point we're all just guessing, and whatever it is, it's getting worse. Shop will figure it out.

Did they quote you on plugs and coils? Labor is never cheap on em but some places seem to want to charge *a lot*.

[lucid21]

Originally Posted by JoepM5

Talked to the BMW M specialist nearby on the phone and he is confident it isn't a misfiring problem (since the car runs perfectly fine after it sputtered, it doesn't shut off cylinders) and he suspects the Low Pressure Fuel Pump (that is inside the gas tank).

I had this exact issue on my E30 M3. I pulled both fuel pumps and tested them. In my case, it was the high pressure fuel pump. They were easy to replace in the E30 but not sure what it would take in the F10. Remove the rear seat cushions should not be hard if you need to get at the LPFP.

[lucid21]

Originally Posted by JoepM5

A fuel issue would at least be in line with my other BMW M - wanted to take out my E30 M3 for a last spin before the winter today and a fuel hose
had gone bad. Probably already leaked a bit before (smelled some fuel in the garage) but now fuel literally was flying out under pressure onto the engine. Luckily the engine was cold...

I suggest checking all fuel hoses. They do become brittle with time. When I replaced the HPFP in my E30 M3, I wiggled it a bit and fuel started leaking from the hose under the car (it wasn't even under pressure at that time). So, I suggest checking that section as well.

[JoepM5]

Hi all,

Apologies for my slow reply/feedback but I took the car to the shop a few months ago and it appeared that one ground wire (not sure it is the correct English translation/word) of one of the ECUs was a bit loose. Tightening of a screw solved it and thereafter it ran without issues!

Thanks for the input!

Best,
Joep

[Blaxwil]

Originally Posted by JoepM5

Hi all,

Apologies for my slow reply/feedback but I took the car to the shop a few months ago and it appeared that one ground wire (not sure it is the correct English translation/word) of one of the ECUs was a bit loose. Tightening of a screw solved it and thereafter it ran without issues!

Thanks for the input!

Best,
Joep

That's exactly what I said your issue could have been a few weeks ago. Glad you got it diagnosed and fixed.

[ygtF90]

Originally Posted by Blaxwil

That's exactly what I said your issue could have been a few weeks ago. Glad you got it diagnosed and fixed.

Hi, I have also exact same issue with my F90, could you please send me a video of your solution? I checked every socket but It looks fine to me, maybe I am missing something

[Blaxwil]

Originally Posted by yigiboi

Hi, I have also exact same issue with my F90, could you please send me a video of your solution? I checked every socket but It looks fine to me, maybe I am missing something

Any recent work done like downpipes or turbos?

[ygtF90]

Originally Posted by Blaxwil

Any recent work done like downpipes or turbos?

Yes, I have lower downpipes. It actually started a week later after my rear differential changed under warranty. I found that there is also a grounding point on the rear dif, can it be my issue?