330 ci BMW

isn't that almost always due to misfire? and if so, you'd have to check out your air, fuel and spark delivery to see if anything's wrong yes?

>>14001946
Not an expert on E46, but my grandpa has one and also has rough idling. As suggested by a friendly mechanic, we opened the gas tank for a few hours. Next time, the idling went to normal.

However, this was a mild case. It might be something else.

check your fuel, ignition and timing

>>14001946
What color is the smoke coming out at the tailpipe? Could be fuel pump. Could be restricted intake/exhaust or maybe the O2 sensors are not working properly. Have you taken the car in the shop for any other problems recently?

>>14001946
Needs new coils, just happened to me a few weeks ago.

Sounds like the same problem with my galant es, low idles, cuts off.
Fuel pump/fuel filter problem most likely

>>14001946
Throttle body position sensor

Before all that, check the intake hose. Had the exact same issues you do and all it cuz of a cracked intakehose fooling the ecu.

Op here, thanks for all the replies anons. It was in the mechanics last week for an oil change only. There is no smoke coming from the tailpipe, could be o2 sensor related, next door neighbor had same problem with his 350Z. It doesn't cut out at idle, but I'll be checking the fuel filters and the intake hose. Thanks for the advice anons

clean the maf, tb and icv

>>14002535
Ok, and what do those letters stand for? I'm seriously car illiterate

>>14002070
Cheers dude, I'll mention that to the mechanic

>>14002565
maf = mass air flow sensor
tb = throttle body
icv = idle control valve

you can clean these with a carb cleaner, coffee filter papers and a can of compressed air

>>14001946
Time to get a new car.

go to autozone and use their odb2 scanner to check for codes.

camshaft position sensor. i absolutely guarantee its this. everybody else is wrong.

>>14004198
>implying scanning for codes is wrong

Disconnect MAF. If it runs better, clean MAF.
Scan for codes.
Without knowing codes, most likely cause is clogged fuel filter and a fuel pump that is dying because of it. Replace both. Super easy, it was the first thing I ever did on any car and I did it with only a glance at a write up.

Ignition Coils. Google how to test E46 ignition coils. Rule that and the plugs out and then check the MAF sensor and then the CCV valve last.

A broken CCV valve with cause positive crankcase pressure and put oil onto the plugs, causing fouling and killing coils. It often is responsible for causing rough idle and destroying coils.

>>14002030
This OP.
my 325ci was doing the same thing.
Service engine light came on and i bought 2 ignition coils for the 5th and 6th cylinder.
That fixed it