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-   -   330Ci rough idle diagnosis (http://forum.e46fanatics.com/showthread.php?t=889663)

fishoutofwater22 12-04-2011 02:33 AM

330Ci rough idle diagnosis
Hello everyone,

The 2002 330Ci I'm driving is my first BMW, and it made this noise when I bought it and still does it now. At that time it had about 114k on it. It now has 120k on it. I've had zero performance problems from it. It cranks easily cold and warm and rpms stay constant at idle. The engine just doesn't sound smooth to me, and I'm wondering if it's a potential problem that may get worse.


I apologize for the crappy video. Still, it's easy to tell that whatever is causing the sound is coming from the right side of the engine. I recently replaced the O2 sensors, and when I had the cabin filter off I didn't see anything obvious.

Any help you can give me in identifying the problem is much appreciated.

Update: The problem is the DISA valve. The butterfly flap on it was loose, and that's what caused the ticking, as well as a dip in performance at low rpms. If you have the same problem, you don't need to buy a new part (they retail for $180 at ECS tuning). Just use this DIY to stop the rattle and make it work right again. People that warn of the metal pin in end falling out and ruining the engine have no idea what they are talking about. There is a pillar in the intake manifold that holds the pin in, in fact, you can see where the pin has hit it over and over if yours was loose like mine.


Also, if your DISA is acting up, you should clean the ICV as well since it probably needs it. Made a huge difference in my case. Idle RPMs went from 1000 to 700 and throttle is much smoother.


Monty330ci 04-28-2015 08:01 PM

Buying a 2002 330ci this month and really appreciate your DIY. It's the small things that cause an owner to send the car in for expensive checkups and unnecessary parts. I am a Process Technician at a auto light fixture plant and have to trouble shoot a vast array of problems. Stay calm and look carefully, chances are it is something simple... and you found it :)

fishoutofwater22 06-27-2016 11:24 PM

Thanks Monty! Sorry I'm just now getting back to you. Been in the Navy and away from civilization for quite some time. Hope all is going well with your 330Ci. Mine has been an absolute joy to drive and learn about. Fantastic car all around.

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