Hi weasel 56 x, thanks for quick response,dipstick ok,oil looks ok,wife stopped as soon as fault happened,car has 40,000miles,service due in 600miles,car never abused.she had music playing loud so bang sounded like big misfire that made me think of overfueling,but engine management designed to overfuel under certain circumstances.car run 40 mile round trip yesterday,same route today only got 32 miles until fault. started engine four times since and always get lots white smoke,smells bad.coolant level ok.