My 2005 X3 3.0l with 90k is starting to idle a little rough after starting in the mornings and idling at red lights. While sitting at a red light you can see the RPM needle slightly jumping up and down. I recently changed the air filter, spark plugs, cleaned the MAF sensor and added fuel injection cleaner but no real changes. I was thinking fuel filter but I am not having any problems with acceleration or fuel economy. Does anyone have any other suggestions?
If is only does it when cold, I'd suggest the idle control valve for further investigation. Further edit: On second thought, perhaps a vacuum leak of some kind as well.
90k is around when the crank vents fail. We check the crank case pressures at the shop with a magnehelic gauge. If I remember correctly, the pressure needs to be under 15 millibar. Also you can look at the bottom of the crank vent where the hose returns back into the dipstick tube. If it coated in oil, and or broken open, you need to replace that and the crank vent. The crank vent is cheap plastic, and all the oil that goes though it destroys the guts inside of it. But you could also have a broken intake air boot. They tend to break on the smaller portion that goes into the stabilizer. Run your hand down it and try to push your finger though it. If it goes though, you need a boot. Just 2 things to check that could be your problem.
