I have a volvo V70 T5 wich is giving up codes 3503 - cat damaging misfires detected
3533 - misfire cylinder 3
The car has had new spark plugs and 1 coil pack but we keep getting the same codes back even though we have swapped the coils , plugs and injectors into different positions.
compression test shows low compression on cylinder 1 but the others are ok
I have occasionally had an air mass signal improbable code but cleaning it seems to have got rid of that. it is showing 1.23 volts at idle and around 4 at wot. Whilst I appreciate this is low I'm not keen to replace it at £190 until I have a full set of compressions and then test it again.
Problem is the vehicle is not worth a huge amount and I am mindfull of taking the head off to sort cyl 1 until I can be sure that the cyl 3 code is related.
Any thoughts ?