[Utvolman99]

So, was just fired from my job and have to give back my company car. Same day, my 2015 328xi decided to take a crap! It’s lightly modified with an intake and a JB4 that was running on map 1.

Anyway, this is what’s going on. Car has rough idle and sometimes dies when stopped. There is no engine light but the car is really running rough.

- noticed black soot coming out the exhaust. I let it idle for a while and could see it spattered on the back wall of the garage.

- I pulled the plugs, to see what I could see and plug 3 (counting from the front of the engine) was solid black. The others were all light brown and clean.

- I changed the plugs with no improvement. Pulled plug 3 and it was black, smelled strongly of gas after a five min drive.

- I cleaned the plug with a steel brush and Installed a new coil pack on #3 with no improvement.

Not sure where to look next?

[Jonwho2]

I have a f32 428i. I was an idiot and decided to buy cheap eBay charpipe/intercooler. The fitmint was shit and I had boost leaks and even blew a hose of a clamp. Anyway the car did exactly what your talking about. Rough idle, would stall coming to a stop etc. check all the pipes coming from and going to your intercooler.

[ScottSmith]

Does it run fine under moderate load, and only sputter at idle?

Get a leakdown test. Not a compression test. I rebuilt a motor on the cheap and still had 30% leakdown in two cylinders but the compression test was "fine." Mine splatters oil out the tailpipe too and consumes oil rapidly.

[dfwF30bmw]

You said you had a company car for awhile, could it be just that your car sat a long time and the gas has gone bad?

[floridaorange]

Return to stock - good luck

[lolbrother]

I had the exact same problem on my 328i. You're a bit more lucky since you have 6 cylinders and the cycles overlap, but on a 4 cylinder it was so bad it was like driving manual for the first time, stalling at every stop. I changed the spark plugs, changed the coil pack, and finally changed the fuel injector. The fuel injector was the root of my problems. To change it you obviously need to buy a new one (mine was around $130 CA) and use a obd computer to change your fuel injector values in the car. It was a quick 45 minute job for me, but for my N20 I needed to buy a special tool to pull the injector. I would recommend doing some research as to what you need for your job. Good luck!

[lolbrother]

Originally Posted by lolbrother

I had the exact same problem on my 328i. You're a bit more lucky since you have 6 cylinders and the cycles overlap, but on a 4 cylinder it was so bad it was like driving manual for the first time, stalling at every stop. I changed the spark plugs, changed the coil pack, and finally changed the fuel injector. The fuel injector was the root of my problems. To change it you obviously need to buy a new one (mine was around $130 CA) and use a obd computer to change your fuel injector values in the car. It was a quick 45 minute job for me, but for my N20 I needed to buy a special tool to pull the injector. I would recommend doing some research as to what you need for your job. Good luck!

Ok I looked into your post more and you have the exact same engine as I do. here is the video I used for reference;

and here is a link to the fuel injector puller for taking the bad injector out; https://www.amazon.ca/BELEY-Injector...xpY2s9dHJ1ZQ==
Something about the N20 fuel injectors makes them go bad over time I guess, as the exact problem you had I had for my second cylinder.

[CalCarNut]

Agree..fuel injector R&R...

[manghong]

I have very similar problems like yours after replacing
- New OEM Spark Plug
- New OEM Coils
- New OEM Engine Valve Cover
- FTP charge pipe (some of my friend have rough idle when coming to a stop but didn't stall)

Symptoms:
- Sometimes the engine stall right after you start the engine(Happen both cold/warm starts), engine usually starts fine at the 2nd time
- Sometimes stall when coming to a stop (most annoying issue)

Not sure where to start to fix this issues, anyone have a hint?Thanks!

[GreenF30N26]

Originally Posted by manghong

I have very similar problems like yours after replacing
- New OEM Spark Plug
- New OEM Coils
- New OEM Engine Valve Cover
- FTP charge pipe (some of my friend have rough idle when coming to a stop but didn't stall)

Symptoms:
- Sometimes the engine stall right after you start the engine(Happen both cold/warm starts), engine usually starts fine at the 2nd time
- Sometimes stall when coming to a stop (most annoying issue)

Not sure where to start to fix this issues, anyone have a hint?Thanks!

Check for leaks from your charge pipe to intercooler and throttle body. Make sure you transferred the rubber seals on both ends and installed them in the right direction. Next check intercooler to turbo pipe then turbo inlet(mine broke and was loosely coming in and out) then airbox to turbo inlet. I had these symptoms twice; once was the broken turbo inlet and the second was a leak in the charge pipe after 20 months of use.

[manghong]

Originally Posted by GreenF30N26

Check for leaks from your charge pipe to intercooler and throttle body. Make sure you transferred the rubber seals on both ends and installed them in the right direction. Next check intercooler to turbo pipe then turbo inlet(mine broke and was loosely coming in and out) then airbox to turbo inlet. I had these symptoms twice; once was the broken turbo inlet and the second was a leak in the charge pipe after 20 months of use.

Thanks man, i have replaced the inlet pipe with FTP ones, it sounded more like the charge pipe issue since it shouldn't touch the inlet during those installation.

[Estorilinca]

Does your OBD reader give you any error codes? My 328 also had rough idle and it turned out to be a faulty upstream O2 sensor.

[Mikereese]

i'm having a similar problem. Just installed downpipe, charge pipe, FMIC. Took her for a test drive and the motor is shuttering and i noticed a lack of power. I didnt put an o ring on the charge pipe to throttle body side, mainly because when i took of the OEM pipe there wasnt one and it never gave me any issues before. could a missing o ring cause all these problems?

[Boznien]

Originally Posted by Mikereese

i'm having a similar problem. Just installed downpipe, charge pipe, FMIC. Took her for a test drive and the motor is shuttering and i noticed a lack of power. I didnt put an o ring on the charge pipe to throttle body side, mainly because when i took of the OEM pipe there wasnt one and it never gave me any issues before. could a missing o ring cause all these problems?

Yes, I put the OEM o-ring on the FTP chargepipe and was having the same issue. I put the o-ring that FTP supplied and ended up solving the issue. Just be sure to use some oil/grease to lube it up before putting the o-ring in! Hope this helps!

[bilko96]

recently installed the MST turbo inlet pipe and intake system and have now got rough idle, i think it is just a vaccum leak and need to tighten everything up.