While investigating a bad idle problem on an MY98 uk turbo,i unplugged each ht lead from the coil pack (centre of inlet manifold) in turn and fired the car up,i noticed that each produced a good spark except 1,see picture below









it did produce spark but not as much as other 3,is this normal or do i have a problem ?

 

Swap the lead and plug from one of the others and try again, if the spark is good, then try it with the original sparkplug, if good, change the lead, if its bad, change the plug.

 

what do u mean by bad idle? is it going up and down? car keeps turning off after accelerating?