[Kienan]

Hello everyone,

I have automatic transmission 3 series E93 2010 BMW which has 115000 km (about 70000 mile).
I bought the car from Germany when it had 56000 mile. The engine is N53 naturally aspirated straight-6 direct injection (consisting of Piëzo-electric injectors directly in the cylinder).

The engine was so smoothly running until one month ago when it got problem of rough idling only on the first start at the morning or after leaving the car to cool down for at least 5 hours. I uploaded a video on Youtube for the first start at morning (I just started the car and the gear is on P and my foot on the brake through the whole video. I didn't press the petrol pedal at all and all the stumbling in the rpm which you see is happening by it self) and here is the link:

as you can see in the video and after about 10 seconds of starting the car and while the engine is trying to idle, the rpm will start to stumble and I can feel the rough vibrations of the engine. After about 3 minutes of running the engine, if I turn it off and then on again, it will run and idle very smoothly and problem free. When this happened for the first few times, it wasn't so rough and it didn't turn the CEL on but then on one morning the problem escalated and the CEL came on so I drove to a local dealer who ran OBD diagnoses which showed a misfiring code in cylinder 6 and he said that it's the sparking plug so he changed the sparking plugs on all the cylinders (BMW standard is to change all and not only the faulty one). That didn't solve the problem so next morning I drove back to him and then he said it's a faulty low pressure fuel sensor but that didn't help again. Then he changed the injector on cylinder nr 6 and the ignition coils on all the cylinders and that didn't help at all. Now the OBD diagnoses shows misfiring on cylinders 1 and 3 so I decided to check by myself and I started the engine then unplugged and replugged the wires of ignition coils for cylinders 1 then 3 and I noticed no change in the engine sound or behavior which means that no firing happens in these two and of course when I unplugged any of the rest I noticed the change in the engine sound. To do this small experiment, it took me 5 minutes which means the engine became warm so I restarted the engine and as usual everything works smoothly and unplugging 1 or 3 makes difference so they are firing normally again!!

can somebody please help me in this problem and help me answering these questions?! Why the misfiring is happening only on cold start and when the engine warms up it disappears? somebody told me that it can be bad or leaked injectors, now what are the odds that three injectors at cylinders 1, 3 and 6 will go bad at the same time?!!!

Thanks in advance,
Kienan

[STR8-6IX]

how often do you change your oil? someone on here was complaining of a rough idle on a cold start just like you. do you follow the bmw oil service intervals?

[Kienan]

Originally Posted by 6IX-F10-N52

how often do you change your oil? someone on here was complaining of a rough idle on a cold start just like you. do you follow the bmw oil service intervals?

I change the oil as the service recommends. My next oil change has to be done soon actually (in 1000 mile).

[STR8-6IX]

Originally Posted by Kienan

I change the oil as the service recommends. My next oil change has to be done soon actually (in 1000 mile).

the BMW service intervals are NOT healthy for your car, and exactly why your engine idles rough until it is warm.

if you drive the car hard/lots of city driving - 4500Mile oil changes
highway driving, relaxed driving - 5000mile intervals will be fine
i suggest you change your oil RIGHT away. change your oil filter a second time if anything. your engine WILL run better on cold starts if you change the oil freuqently.

[Kienan]

Originally Posted by 6IX-F10-N52

the BMW service intervals are NOT healthy for your car, and exactly why your engine idles rough until it is warm.

if you drive the car hard/lots of city driving - 4500Mile oil changes
highway driving, relaxed driving - 5000mile intervals will be fine
i suggest you change your oil RIGHT away. change your oil filter a second time if anything. your engine WILL run better on cold starts if you change the oil freuqently.

Thanks for the advice. I will try this and change the oil on Monday and I'll update this post whether that step will solve my car problem or not.

[STR8-6IX]

Originally Posted by Kienan

Thanks for the advice. I will try this and change the oil on Monday and I'll update this post whether that step will solve my car problem or not.

right on. you may want to consider changing oil filter twice. you can check your oil afterwards on the bottom of the oil filler cap or through the filter housing if it is clean or not. with the intervals BMW "recommends" and your cold start issue, you very well may have sludge, or dirty engine oil even after a change.

[rjahl]

Try swapping the coils from the bad cylinders with a good one and test again. It's not impossible for the new coils to be bad.

A long time ago I swapped points and condensers on a car and spent the whole day trying to get the car running correctly. Turned out that new condenser was bad. Popped the old one back in and poof car ran correctly.

[Kienan]

Originally Posted by rjahl

Try swapping the coils from the bad cylinders with a good one and test again. It's not impossible for the new coils to be bad.

A long time ago I swapped points and condensers on a car and spent the whole day trying to get the car running correctly. Turned out that new condenser was bad. Popped the old one back in and poof car ran correctly.

well I tried to do this and I swapped the coils but still the misfiring happens on cylinders 1 and 3. Next day I swapped even the sparking plug and still 1 and 3 misfiring. Just yesterday after a very rough start and CEL, I drove the car to a workshop for OBD diagnoses and he said he got misfiring codes on cylinders 1, 3 and 6 which confuses me more now!!! cylinder 6 has the sparking plug, coil and injector changed just two months ago (at 69500 mile)

[STR8-6IX]

Originally Posted by Kienan

well I tried to do this and I swapped the coils but still the misfiring happens on cylinders 1 and 3. Next day I swapped even the sparking plug and still 1 and 3 misfiring. Just yesterday after a very rough start and CEL, I drove the car to a workshop for OBD diagnoses and he said he got misfiring codes on cylinders 1, 3 and 6 which confuses me more now!!! cylinder 6 has the sparking plug, coil and injector changed just two months ago (at 69500 mile)

your idle will smooth out if you have clean oil in the crankcase.

[stewey]

Originally Posted by 6IX-F10-N52

your idle will smooth out if you have clean oil in the crankcase.

Say what now? The cleanliness of your oil does not correlate to the quality of your idle.

[Kienan]

Originally Posted by 6IX-F10-N52

your idle will smooth out if you have clean oil in the crankcase.

I changed the oil and the filter last week and it didn't solve my problem. It didn't have even any slight effect on the idling. I asked the workshop to check the old oil for any metal particles and he said that there were no particles and the oil.

[matteblue3er]

N53 is direct injected. Might need a walnut blast

[S.H]

My 2007 e93 N53 with similar mileage had same symptoms as this one. The garage found coolant in the sylinders causing misfires and ultimately engine not starting at all (but starter cranking). The car is still at the garage as they recommended a full engine swap (because of the cost involved in tearing the engine apart to find the root cause). Maybe I'll start a thread later with all the details.

[STR8-6IX]

Originally Posted by matteblue3er

N53 is direct injected. Might need a walnut blast

Seconded. A walnut blast is very likely to solve your problem.

[Rocklicker]

Hi that was me with the cold start on a IDI N52. Still working on that, but a serious issue was the P-side engine ground strap had snapped and the D-side was blue and fraying. Bad electricity is bad for everything. I'm still mid-fixing things so don't want to speculate here but bad electricity is bad for everything. Passanger side strap is very visible from above with hood open give it a quick look just to "check that box". Cross-linking my thread for helpfulness: http://www.e90post.com/forums/showthread.php?p=20998884

[Kienan]

Good morning everybody,

Finally I were able to get an appointment in BMW service and they ran a diagnosis and compression test on the engine and they told me that the injectors are going bad and have to be changed. Since I have had the injector on cylinder 6 been changed just at 69500 mile, they suggested to change 5 injectors and test it. So I have had new injectors installed and the engine is full of life again, the cold start rough idle problem is solved and the engine power is back to normal.
Thank you all for your suggestions and I hope that this post will be helpful for the rest of us.

Merry Christmas and Happy new year

[Atx328]

I am having a similar but less severe problem. I will try new plugs first but I hope it doesn't come to injectors

[Kienan]

Originally Posted by Atx328

I am having a similar but less severe problem. I will try new plugs first but I hope it doesn't come to injectors

It started in my car in such a way you can hardly notice then it escalated in about 2 months to the way you see in the video. When only one cylinder in 6 inline engine is misfiring, you won't feel any impact on your engine performance and I believe that was my case at the beginning then when also one more cylinders joined the party and misfired, it resulted in the severe way you saw in the video.

Changing the sparkplugs doesn't cost alot, so you can start with this.

[Terraphantm]

My dad's N54 (same injectors) was having similar issues. Changed all 6 injectors last night with the latest version, and so far it's driving great.

[e90dum]

Originally Posted by Kienan

Good morning everybody,

Finally I were able to get an appointment in BMW service and they ran a diagnosis and compression test on the engine and they told me that the injectors are going bad and have to be changed. Since I have had the injector on cylinder 6 been changed just at 69500 mile, they suggested to change 5 injectors and test it. So I have had new injectors installed and the engine is full of life again, the cold start rough idle problem is solved and the engine power is back to normal.
Thank you all for your suggestions and I hope that this post will be helpful for the rest of us.

Merry Christmas and Happy new year

That's great to hear

by the way I'd say 7000-9000 is fine for an oil change I do mine every 6000 because I like spending money but BMW isn't that far off.