Last update:


  Loom damage DOHC

About Us Useful Links Forums Mailing List


On Board Diagnostics
24V Cosworth rebuild
Loom damage 24V
Diesel loses power
Poor Engine Idling
Idle Problems
Testing the MAF
Cleaning the MAF
PCM Repair
Loom damage DOHC
EGR Repairs
Engine flatspot?
Engine Cleaning
Misfire #2
PCM Software Update
Stainless Exhaust
Sump Plug
Timing Chains (all)
Timing Chain 2.0 16V
Timing Chains 2.9 24V
Oil Additives
Engine Rattle
Engine Manuals
Exhaust Manual
Vacuum Pipes on 24V

Vehicle Ultima 16V 2.0 & 2.3 Saloon
Year All
Mileage Any
Repair Cost 90 + fitting
Repair Part(s) Ignition Wiring Loom
In the case of the DOHC engines, both the 2 Litre 16V and the 2.3 16V use a wiring loom connecting the engine sensors and the two ignition modules which fire the spark plugs. The loom snakes about around the front of the cylinder head and across the inlet manifold and part of it enters the cylinder head cover.

Experience has shown that the insulation on these wires is vulnerable to cracking. This can allow signal loss or induction, and even shorting, and this leads to misfire, hesitation on acceleration, and poor or unstable idle.

The picture below shows the damaged loom from Pete C's 2L 16V. It had been temporarily repaired with insulation tape by a local garage mechanic who had spotted it during an MOT inspection.

The condition of the insulation can clearly be seen on this shot from Pete C. Deep cracks and the complete loss of insulation close to this plug. The merest touch against each other, or to earth on the cylinder head, or a touch of moisture and you have loss of signal to the spark modules and misfires.

The loom concerned is called the Fuel Cut-off Loom and this should be inspected carefully, especially beneath the inspection cover on the cylinder head where the heat appears to cause the wire insulation to crack. If any cracking is found it would be possible to insulate or replace damaged areas, wire by wire, but realistically this can only be regarded as a temporary measure.

The loom can be ordered from a Ford Main Dealer, cost about 90, depending on discounts available. It can be fitted by the owner.

Dell, a 2.3 owner, fitted his own loom and supplied the following pictures. Although it looks intimidating he states that it fairly easy to fit.


He did it piece by piece, starting at the top of the engine by disconnecting the coils first and worked his way down to the bottom, disconnecting the old and connecting the new as he went along. It was daunting to look at but quite straightforward to carry out.


His only difficulty was connecting the last 2 plugs due to having short arms. One was a small circular rubber plug with a central connector which had to be pushed onto a single pin (like a small threaded bolt) around the oil filter area on the engine block, having short arms made it difficult to push home. The other was a multi plug near the rear of the engine underneath, the original route went around a "strut": it plugged in but he didn't seem to have enough slack so just took it direct. A friend of his with longer arms did it in a jiffy, where Dell had been struggling for some time.

Nodge on the Forum also advises a careful check on the Coil Packs.  He has found damage to the HT extension that passes down to the spark plug:

Above, the crack Nodge found on the coil pack can clearly be seen - this caused a misfire, so be prepared to change the pack if this is found.

Thanks to Pete C and Dell for the pix and detail and to Nodge for the last pic.




Copyright 2003