Fuel trim, read by diagnostic scanner. The fuel trim determines how much fuel is delivered when driving and at idle. As I understand it the oxygen sensors fluctuate between rich and lean and this determines the fuel trim. I'm struggling to understand why I have this problem so if anybody has any ideas about what could be causing it I'd be grateful to hear them.
I serviced the car when it started happening and it's no better. If I blip the throttle a few times when it happens and take the revs up to about 2000rpm the car settles down to a normal idle and the short term fuel trim sits at around 0% give or take 2%.
