Rough cold idle and hesitation E61
I have a question that so far the dealer has yet to answer or resolve for me.
I have E61 535xi (2009) that I bought as a CPO last year. I love the car, but am having an issue.
This winter the car started to perform poorly, especially in the mornings, when for the first little while after I started it. I took it to the dealer and they told me there was a software update that would help as there was an update that affected the oxygen sensor. I had to take it back to the place I bought it as they agreed to do the software fix for free.
The software has now been updated but I still get rough idle at start up in the morning, and my fuel economy is getting worse, now at about 16 mpg (13.2 l per 100km). I was getting 19/20 mpg last fall.
The injectors have been replaced under warranty by the original owner. The HPFP was also replaced twice.
Sorry for the long post, but does anyone have any suggestions? Thanks in advance for any help.