Originally Posted by BMWHacker
I did a service on the weekend, did the oil, fuel filter and air filter.
The car came with a K&N filter and I've been driving it for about 4 months now without any problems. I'm not a big fan of these filters so I decided to change it to an OEM Mahle filter.
The K&N filter was filthy and looked fit for the bin, so I was fairly sure putting in the new filter would be an improvement.
However, I've noticed since the change that the car now has a flat-spot around 1500-2000 rpm when in 3rd and 4th gear, especially when driving around town. It's also a bit more hesitant when accelerating.
Like I said, I'm not a fan of aftermarket filters, I've tried them before and never noticed any performance gains when using them.
Any one else ever experience this? Is it possible the air filter could make that much difference or did I mess up something else during the service. :smiling: