AndyKam

iTrader: (2)

My L6 managed FRST has a misfire on cylinder no.4 when revs exceed 3K. It idles with no problems but when the revs exceed 3K you can hear the cylinder sort of switch off. I increased the revs up to where it starts to miss and pulled off HT lead number 4 and confirmed that its this one thats got the fault.

Any ideas what this could be? Its not burning any oil and there is no smoke coming out whatsoever.

Thanks

Andy

MK5RST

Have you tried the obvious of a new plug in there? plug lead? sounds like something is braking down under load.....

AndyKam

iTrader: (2)

I fitted a new set of plugs as soon as I noticed there was a problem but even with the new set the same thing occurs.

I havent changed the plug lead yet so I'll swop them over tomorrow and see what happens.

I am worried its something serious.

AndyKam

iTrader: (2)

I managed to swop over the plugs and leads today but still the same problem. I have checked the distributor cap and thats seems fine too.

When I checked the plugs they seemed fine maybe a little sooty but they are not wet with either petrol or oil.

Any suggestions?

S1

if you can, swing the dizzy round 90degrees and move the leads back to their right positions, this should prove out whether its the dizzy or cap at fault. If its still missing on the same cylinder, swap the plug lead. If it's still there then it could be a valve not seating or some other problem with compression. Have you done a compression check?