Hi,
Not needed to post here for a while so must be getting good ;)
I know someone whose Focus (2005 1.6 LX) is intermittently misfiring in heavy rain (MIL light flashes) and the garage they took it to have been unable to fix. Ergo I thought I'd appeal to the collective wisdom here so I don't give bad advice :)
Apparently the spark plugs and leads have been replaced (one of the plugs was rusted in) and a new cover has been installed over the plugs to try and keep water out but to no avail. The seals round the washer jets have been tested and are fine.
Despite the replacements it still sounds like the spark plugs aren't firing to me so could it be the coil pack? Another thing that occurs is water getting to the MAF or it's wiring resulting in running too lean, does that sound likely (doesn't to me but it's a thought) ?
Thanks for your help as always,
Peter.