Hi. Did you guys ever find the solution to your misfire and limp mode problem at start up? I have a 2015F56 MCS at 130k doing the exact same thing. Replaced plugs, coils and fuel breather valve. No luck. Only does it occasionally like once a month. Restarting it once or twice usually fixes it. Codes are multiple misfires across various cylinders. Thanks!

 

I have not fixed this issue and could not find leaks; the issue came up again yesterday and today. Restarting did the trick... The fuel trim readings and o2 sensor readings are off? Planning to take it to shop tomorrow.
Some data:

 

I think what I was going to alert you to back in November when I made that post was the possibility that the fuel tank vent valve (sitting right on top of the intake manifold, under the "pretty cover") might be in play. Cheap to replace, Bosch-branded part will do you just fine (they manufacture the genuine BMW part), 15 minute job tops, don't have to unscrew or unbolt a thing. Mine went bad and tanked my fuel economy like nobody's business, replacing it restored things to normal. And been seeing lots of folks talking about having to deal with them in other forums.

That said, I haven't seen or heard of one yet that would be fixed even temporarily by restarting the engine. So probably doesn't apply. Let us know what the shop says!

 

Just had drivetrain malfunction come back on highway full throttle consistently. Thinking it might be fuel injectors that need to be cleaned. Checked spark plugs which looked okay.

By the way a faulty vent valve can be easily diagnosed. When you fill up the car with gasoline, if it's faulty the car will have a hard time starting. I replaced mine so I know.

 

Not quite. Yes, your scenario is one way a faulty vent valve can show up. No, it is not the only one.

I never had a starting problem. Not once. But my fuel economy went into the floor and when I took the part out of the car to examine it, I found that it was leaking fluid from its seams. Said fluid got all over my hands.

Now, as fuel tank vent valves are not supposed to leak fluid from their seams, mine was clearly broken. And since it wasn't doing this before then (I am under the hood of my car A LOT), and the time of the leaking correlated with my fuel economy going through the floor, and finally, with my fuel economy recovering when I replaced the valve, it would be a reach to claim the broken (again, actively leaking fluid from its seams) fuel tank vent valve was not root cause.

I have seen a LOT of people claim that fuel tank vent valve failure shows up only one way, and the one way is the one way they have seen personally, and that if that one way is not in the symptom tank the fuel tank vent valve is fine. Had I listened to those people I never would have popped the hood and taken a look. And I found a broken fuel tank vent valve leaking fluid to prove the point.

So -- "must have hard time starting or it's fine" -- wrong.

Hope this reminder that there can be lots of symptoms besides the ones someone has seen personally -- it's not "either or" in many cases so much as "both/and/or" -- helps folks.

 

Dealer merely checked compression and swapped spark plugs... 'fixed' now. the replaced oem plugs only had 19k miles on them... fully expect issue to reappear soon.

I did have a vent valve issue before and it did have trouble starting after fillup. This is not the same issue imo.

 

Bought some Redline Fuel System cleaner and ran through half a tank of gas so far. Issue seems to have gone away. This was recommended as the strongest available fuel system cleaner.

 

Hi guys,

I have an F55 Cooper S, 2016/17, 5 door and I had all of these issues mentioned above.

I took it to my Mini dealer and they replaced all 4 injectors and plugs.

All problems fixed and he runs like a dream.

Peter.

 

The Redline product contains an effective level of polyetheramine (PEA), which removes carbon deposits from injectors. Other products that also contain effective levels of PEA are from Gumout and Driven Racing. If buying the Gumout product make sure that the label includes the word "Regane" a reference to "PEA" as Gumout produces a number of fuel system cleaners and not all contain PEA.

See a discussion here @ 9:38:

 

injectors or ignition coils?

 

I passed 150k mi so i decided to swap both o2 sensors and map sensor (all oem) and ran the redline fuel cleaner. so far it has not had drivetrain malfunction at startup but now it does if i accelerate hard (however no check engine light and no trembling, only sluggish acceleration at that point). might i have left something incorrectly installed? was a pain to get to/replace o2 sensors. ill get some obd data on sensors...

 

When was the last time you replaced your plugs or potentially coil packs? Guessing you may be 'blowing out the flame' from your plugs and while not enough to trigger a mis-fire, may be just 'weak' combustion going on. As boost pressure goes up, your spark gap resistance goes up, so if you have worn plugs (i.e.- larger gap) then you could run into issues under high boost/load conditions like you are describing. Just a thought.

 

P0456 code came up now but no misfires afaik. Plugs maybe 5k, coils ill have to check but dealer replaced maybe 50k ago.

At idle: Long term fuel trim bank 1 like 10.0%, short term about 0.1%. o2 lambda ~1V, o2 secondary ~ 0.8V.
What is long term fuel supposed to be at idle lol ugh

Edit: got bimmerlink code 190302. changing a hose clamp on the intake maybe that helps...

Edit2: changed hose clamp, cleared codes. on attempted accelerating hard, the drivetrain malfunction error came up. bimmerlink code 120308 now.

Edit3: found a manual. What would doing what the manual states not to do cause damage wise to the turbo? I did that:

I did the 'don't do this' part.