Recently when starting the car with a cold engine it has felt like it is struggling to drive smoothly for the first few miles, like its not fueling right. When its particularly cold (but its the UK so still only 6-8c) then its quite bad for the first half mile, misfiring and jerking as if it firing on 3 only!
The revs have also taken to hunting at idle for all engine temeratures (although especially when cold) and rev up and down, although never actually die completely.
Higher revs over about 5Krpm feel a bit gutless but then the next time I try can be ok again.
A dodgy plug or coil pack doesn`t seem to fit so i can only guess its fuel problems. As I`ve got LPG I can compare this with Petrol but both seem to have similar problems (although the lpg doesn`t kick in when the engine is cold by design) which points to a sensor somewhere.
My immediate thought of the lambda doesn`t seem right as the LPG fuel mapping is poor until the lamda is warm (30 secs after the car is started) and you can distinctly feel the benefit when the lambda has warmed.
I`m a bit lost as to what it can be but the car is not performing well and a Ford Mucas overtook me on the motorway
Is it possible that the lambda can deteriorate and become erratic? Any other sensor ideas? I thought of MAF to but can that be erratic or does that degrade in a linear fashion? I can understand failure or gradual failure but not this back and forth between ok-ish and poor.
Its a tough one I know but any advice or clues would be appreciated!