My 84 f 150 had a bad dissy so i swaped it out with one off of a truck that was running fine put a new cap rotor wires and plugs in and set the timing with a light. with the eec lead plugged in the engine is miss firing on the #5 cyl. but all others fire faultlessly if i unplug the lead as though setting the intial timing all the cyl. fire with no problem. I even tried swapping the cap out with the old one and have the same results . i also thested the #5 wire and plug and have the same results with a different plug and wire installed. it is equiped with an eec iv ignition system and has a new module and pick up coil as well as a reman ignition coil
Are you 100% the dissy is ok? If the bush at the top was worn the chopper wheel might be rubbing on the hall sensor and maybe correspond with #5. OR maybe it is the wrong dissy for your car (some 6cyl dissy's have one vane on the chopper wheel narrower than the other 5). Also, there is NO SUCH THING as a remanufactured ignition coil - only new or secondhand.
Thanks for your reply i did check out the chopper wheel in the new dissy and it is different so i swapped the shaft and chopper wheel out of the old dissy and i was wondering if the dissy drive gear needs to be oreinted any particular way or if the pin drops in that is what lines it up in other words can the gear be installed back wards
Sorry, I cannot remember which way the gear goes. Have a look in a workshop manual. Maybe. A computer fault will not cause a misfire on plug #5 only. (ford ecu's are very reliable, unlike their holden counterparts.)