1998 Ford Fiesta 1.3 Endura -E engine.Cylinders 1 & 2 sparks perfectly,when disconnecting HT Leads idling changes,But HT Leads on 3 & 4 no change in idling when removed from spark plugs,Although sparking comes from the HT Leads.Engine basicly running on cylinder 1 & 2 What could be the cause.

Stanley H, July 2009

The Cam Followers operating the pushrods & valves may have worn down on the affected cylinders, it's quite common on the endura e unfortunately. Other than that it could be fuel injectors (as mentioned).

Pete, August 2009

If you are certain that the HT leads are sparking, then your fault will be with the fuel injectors.....if you can disconnect the electrical connection to them and connect a meter set to measure resistance across the two injector connections you are looking for a resistance of about 16 ohms. They should all be equal.

John, July 2009