Hey all. Have a '15 Mini Cooper S F56. 125k mi.

Sometimes upon startup, within seconds, I get Drivetrain Malfunction and to drive moderately and get misfire engine codes P0300 P0301 P0304. This never happens mid drive. Resolves itself by shutting on and off at least once... I don't know what is wrong. I was thinking fuel related. Anyone have any ideas or experience with this? I have changed spark plugs and dealer changed ignition coils recently (see next paragraph).

I took it to dealer under SULEV warranty probably less than 6mo ago and after about a week of diagnosing they decided to change ignition coils... I thought it was fixed but issue is sporadic so maybe I was just lucky to not experience issue for a while and they didn't fix anything.

Any thoughts appreciated, thanks.

 

These are cylinder misfire codes on #1 & #4. If it took Mini a week to diagnose the first time, that would be a good reason to find another shop for further diagnostics

 

Could be fuel but my first hand experience is fuel related issues are few and far between. Hope I don't jinx myself but in about 1M miles of driving never encountered "bad fuel". And the few times I've come upon someone with a real fuel problem the symptoms are much worse.

'course, if the engine is not running *that* bad you can drive the car and use up the (suspected) bad fuel and then fill up with good fuel. You can add a bottle of Techron -- follow instructions on the bottle -- to not necessarily address the bad fuel -- Techron is not intended to do that -- but to remove fuel system (injector) and valve and combustion chamber and O2 sensor and even converter deposits.

Had one car manifest a CEL shortly after cold start when I let it idle a bit. Misfires were the cause of the CEL. Had the car in. Tech thought it might be lazy injectors but advised a wait and see course of action. New injectors was a "fiddly" job and expensive. (Oh, the car was a 2003 Porsche 996 Turbo.)

My cure, well work-around, was to just avoid letting the engine cold idle for any length of time. I'd start the cold engine and after just a moment or two once I had checked for any issues I'd back the car out of the carport and of course driving it easy just drive the car. No misfires. No CEL.

Time passes. At some point the battery went bad.

Then I had to replace the O2 sensors -- one went bad. This at 132K miles. With new O2 sensors the engine ran better.

Then some time later on a whim and curious I had the coils replaced along with the plugs. The coils were original with over 132K miles on them and the plugs were about 10K miles from their change by miles. After new coils and plugs (tech said while he was there the plugs should be changed and I agreed) the engine ran better.

Then some 10K miles or more after new coils and plugs I had to have the alternator replaced.

At any rate at some point after all the above I noticed no more cold misfires.

What was the cure?

Well, certainly one wants to "believe" it was new coils/plugs or even new O2 sensors. That after new sensors and then later new coils (and plugs) were installed the engine ran better sure leads one to believe it was new sensors or new coils.

However, I will mention with other cars -- since I owned the Turbo -- I found they do not like to sit unused for any length of time. I did let the Turbo sit unused -- locked and in about as low power mode as it could be -- for sometimes nearly a week between uses. That the battery went bad and then the alternator -- not blaming either on letting the car sit -- I could sort of suspect the misfires might have been due to a low battery voltage problem due a battery on its way out or even due to the alternator output falling off over time.

(Due to where I had to park the car I could not connect a battery maintainer to the car.)

Have to mention with other cars while they manifested issues from lack of use these issues disappeared with more frequent and longer duration use.

So drive the car more often and for more than just a short trip and see if the behavior goes away. That's easy enough to do I guess.

But before you drive the car more a thorough inspection of the car's battery connection and cabling and this includes at the other ends of the battery cables not just at the battery posts to ensure all is good could prove to be enlightening.

 

Has the car been tuned? Did you buy it used? Could it have had a tune on it previously?

I've had a misfire code with this drivetrain limp mode but only when doing WOT pulls with a race map tune.

I would perform a transmission and engine adaptation reset. You can either do this with or without an ODB tool.

 

Hey peeps. I know these are misfire codes hehe and I left a horrid experience review with them so def not going there again lol.

So as far as fuel I was thinking moreso along the lines of fuel delivery either injectors or pump but that was just a guess as I think coils and plugs are good.

This is my every-ride car. Commute daily 100mi. The battery was replaced around the same time as coils (non oem) while trying to fix misfires.

I purchased car with 3k miles from mini dealer. I have not tuned the car.

 

Misfired this morning restarted couple times. good to go. But noticed oxygen sensor 1 is 0.00V and oxygen sensor 2 is 1.27V. Don't think that is right. Searched if O2 sensor can produce misfire -> yes. Will try replacing #1...

 

hey I’m getting the same issue currently , and I’ve change spark plugs for all cylinders and coils , but here I am a week later with the same issue and same cylinders 1 and 4 miss firing. Where they able to resolve your issue and if so what was

 

Possibly knock sensor related issues. Not sure. Would also clean MAF as a first step. Good to get that out of the way as it's easy.

 

Hey. Sorry to hear you got same issue. Uhm so I was going to change O2 sensor but its like $400 oem so decided to take to another mini dealer as O2 sensor is covered under SULEV warranty. Anyways they had to do their own diagnostics but they came back with a tiny gas tank vent leak or something, will check later lol. They fixed that and now this Tuesday the same misfire issue happened but restarting couple times fixed it but check engine code went away and I was going to take back in tomorrow, Friday. Anyway they also suggested I change spark plugs so instead of letting them do it for $430+ I walked to their parts store got them for $130. Anyways going to do other repairs right now. Needs new motor mount and brakes/rotors. I will take it in if it does it again sucks I only got time on weekends though that's why I didn't take Tuesday.

I will have to look at this, thanks.

 

thank you , I checked my o2 sensors and it looks good , not much build up on the ends so that might check out. Might do a compression test and get too my knock sensor, but the sensor is under the manifold and I don’t know if I wanna pull that off. Might Planning on taking it too my mini dealer near by, a friend had the same issue and his was timing related and we’re sitting at the same miles.

 

Could the misfires be from carbon build up on the intake valves? BMW apparently improved the DI carbon issues with the B series engines, but at that mileage, it might need an intake service?

 

I have not got new timing/belt done yet while obviously overdue think recommended at 60k.
thx for pointing out no belt lol

 

Your 2015 Cooper S has either a B46 or B48 engine (probably B46) -- both of which use a timing chain, not a belt. So definitely not a 60k interval belt change.

No specific interval that I'm aware of for timing chain work. Not that it will never need service, just no specific interval I'm aware of.

FYI

 

I have a 2017 F56 S with a B46 engine and have eyeballed my intake valves (most recently at 103K miles). I am familiar with this issue from my R56 (I eyeballed those too).

No special service history on my B46. I have probably personally spent more time sniffing around inside it than the prior owner (very non-technical person) and their service techs combined (I bought the car at 72K miles).

The carbon on my B46's intake valves is so minimal it doesn't even remotely compare with the kind of intake service one would be thinking of for the N14 and N18 R series engines. Not that there is no carbon, but absolutely nothing about it says "get walnut blasting." And even though my last look was at 103K miles, I would be amazed if that general assessment changed by the time I get to 125K miles. I will probably do some cleaning my way, but I definitely do not expect "walnut blasting level buildup" to appear by 125K.

That said, I'd be surprised if that was the source of the OP's misfires. I mean, anything is possible, but I'd be surprised. Personally, my troubleshooting list, in the following order would be (and OP has already done some of this):

- plugs
- coils
- O2 sensor (specifically the one before the cat - it controls air/fuel mixture) if suspect. Note that O2 sensors, despite not throwing a check engine light for a LONG time in most cases, are generally only rated for 100K miles, hence the "if suspect" part. Related to this, if one can get real-time fuel trim data, see if the short-term and long-term fuel trim values look weird -- if strong signs of running lean or running rich, the pre-cat O2 comes under scrutiny (on any car).
- gather all codes no matter what level they are, clear codes, troubleshoot any codes that come back within first engine run or two or three. Really important to do this sort of gather/clear/see what returns. One doesn't want to end up chasing codes that are no longer relevant/aren't coming back.

From there it's a hunting exercise. I have other thoughts but I don't think they really apply until that last step in particular is taken.

 

Bank 1 O2 sensor was reading no voltage afaik while bank 2 was. I even hit the gas to check and no change to Bank 1, which I am assuming is pre-cat. I'll have to check it again.

 

I concur, bank 1 would be pre-cat (at least it is on my not-MINI other vehicle).

 

so I checked my o2 sensors and b1 sensor 2 was reading .8 v at idle , but b1 sensor 1 was reading at -.02 (mA) at idle. I believe (mA) is milliamps. So I’m guessing it’s not getting any at all.






top is just power on , bottom is idle

 

@evans56 if that STFT reading stands for short term fuel trim, 99.2% is off the charts and the car is adding fuel because it thinks you're running lean (too much air, vs. fuel).

Your lambda value on bank 1 sensor 1 being above 1 agrees with too much air vs fuel, which would (numerically) prompt adding fuel. But you're not above 1 by much (0.004). I can't say for sure whether that is enough to explain the STFT looking like it's heavily enriching your air/fuel mixture with fuel, my experience with lambda sensitivity is not extensive.

That said, TIS says the max V that should be showing for the O2 sensor after the cat is 1.0V. Looks like you're showing 1.25V. How many miles on this O2 sensor?

 

77,843 neither o2 sensors have been changed

 

Hmm, and what year is the car?

 

It’s a 2017 cooper s

 

Got it. Same as mine.

So I dug out the 2017 Mini maintenance book and it says O2 sensors should go to 120K miles on the JCW and 150K miles on the base and S.

Can you find LTFT (long term fuel trim) in that scanner?

 

let me do another drive cycle since I had cleared the codes and I’ll be right back with it

 

Ok. Get bank 1 sensor 1 voltage as well.

 

I did some driving and when idling b1 s1 says -.02 ma and when I do pull/cruise it’s around 1.0-1.3