Polo misfiring when idling

[mm707]

Hi - I have a polo 1.0 1999, it is misfiring on cylinder 4 when idling - when I get the speed up it is ok. A garage has put in a new plug / lead / dist cap and swapped the fuel injectors around all of which has not fixed it. ( It does seem to be a lot worse since it went in for it's mot and a new cat and exhaust was fitted ?? )

The car has done about 50k miles.

Any ideas what to look for would be appreciated.

Thanks

[dickelms]

I think you'll have to use a compression tester - I did that , pressure was down to 100psi (should be nearer 200) so had to replace the valves on that cylinder.... :mad: