I have a 2004 BMW X3 3.0i and it runs rough and kind of sputters when idling. When stop @ a red light it feels as though it's going to die, it idles under 1 rpms. It also gets very bad gas mileage. I was told I need a new cabin air filter and that it may help me get better gas mileage, do I also need to change my other air filter too? So two questions, why is my car idling rough and how can I get better gas mileage?
I would like to start with a question, is the check engine light remaining on when you are driving the car? The cabin filter might need to be replaced, it will not have any effect on the fuel economy. The poor fuel economy may well be due to the air filter element, when was it last replaced? The rough idle is possibly due to something like a contaminated air filter or perhaps something more involved, but I always like to start with the easy stuff so that the possibility of a clogged air filter can be removed from the equation.
November, 7, 2012 AT 4:41 PM
Ihad same problem with a 2007 X3---took it into local shop and they changed a coil pack. I've now done this 5 tmes since owning, and every time, within 2 weeks the engine light is back on.