Mondeo - Zetec 1.8 - Plug 4 missing during idle
Hello Folks, need to pick your brains again please.
My girlfriend has a 1997 1.8 mondeo, 115ps, with 48000 miles on it.
tonight I jumped in, and found it very lumpy at idle, but normal to drive.
Taking a closer look, I've traced the problem to number 4 plug. It was black and oily, & fouled pretty bad. Looking down the plughole, the cylinder top is very oily.
The car misses during idle, however up the revs, past 1000, the engine seems to stop missing, and when driving it, its fine and appears to use all 4 plugs normally.
I've tried changing the plug leads, no difference
I've changed spark plugs 3 & 4 around (having no spare plugs) I'll check number 4 tomorow night.
The only other thing I can think could be the DIS / ignition box? but I dont have a spare or donor car to rob bits off
Does anyone have any other ideas??????
Thanks
CHRIS