I have a black top Zetec on Jenveys with Lumenition. At Le Mans last year it was misfiring, turned out that the Crank sensor wires were close to some other feed. It now has started to misfire in the same way. Symptoms are all cylinders cutting out at about 5% of the time throughout the whole rev range. All the primaries are equal temp. Any ideas welcome. Jon

Jon, Is your wire from the CPS correctly shielded? From memory I think it needs to be shielded and only one end of the shield needs to be connected to earth. Bit like old fashioned TV aerial cable.

Funnily enough I checked the earthing of the shielding and the terminal had disconnected. I soldered a new one on and it has improved. the last 100 mm to the connector has no shielding so I may make some up.

Hi, can i suggest you check the crank position sensor, had 1 fail at abingdon 3 weeks ago, wore away, dont know how.

Thanks for the replies. I have changed the crank sensor and put another connector on but still have a misfire. It is across all 4 cylinders and is missing about 5% of the time. I am sure it is something simple that I have done but dont know what. I put a new alternator in over the winter as well as a new battery but have not changed any thing else.

From my experience with these,

The plugs don’t like to be wet. Get a new set of genuine ford plugs.

I’ve had a couple of coil packs play up over the years. Does the lumenition use them ?

The lumenition ecu is erm a little dated. I would be going through the loom and plugs checking for corrosion.

Thanks for the reply, It does use the ford coil pack and two lumenition drivers. I have ordered a new coil pack and will give it a go. As I mentioned the engine is miss firing across all 4 cylinders as the primaries are all the same temperature so it suggests something further back.

Yes coil packs usually play up on two not all four unless it’s a power suply problem. Plugs are all ways a cheap elimination item.

Corrosion to terminals in plugs, bad earths are all likley suspects with cars stood over winter.

Was the loom a purpose made loom or recycled ford ?
90’s ford wiring really suffers from cracked insulation and the Black Death where the conductor corrodes inside the insulator.