Mondeo Misfire

Hi My 1995 Mondeo,Zetec, has done 81000 miles, it had an new timing belt last year.

Recently it was pulling badly, seemed to get worse over a couple of months, so I put it in for a service at a local garage (not ford) and asked them to check for underpower problem.

They changed the plugs and said the HT lead 4 was arcing and I needed to replace the leads. They had sprayed the leads with WD40 as a temp fix.

However although the car was pulling much better after about 5 miles a random misfire occurred, doesn't seem to matter whether car is pulling hard or not.

I took it back to garage, they replaced Coil and thermostat which was stuck open.

I drove about 500 miles the following weekend and the problem did not occur, but a couple of days later after about 5 miles the misfire is back.

As a long shot when this starts to happen after about 5 miles, I turned the ignition off and on, low and behold the misfire is gone until the next time I start the car from cold.

So what's happening here, am I resetting the ecu or am I fooling it into thinking the car is just starting and providing a stronger petrol/air mixture,or something else.

I wonder if the Halfords leads I fitted are man enough and also if the plug gaps are too big (not checked them yet)

Any ideas anyone?

Thanks Roger

Reply to
Roger
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In message , Roger writes

[snip]

Stop wondering........ they're not!

Get some Motorcraft leads on and fit new Motorcraft plugs while you are at it.

Reply to
Paul Giverin

Here's your problem- Zetec HT leads are a known (very) weak spot- its always number 4 which goes first, and Halfords "leads" will be without a doubt totally s*1t.

In many peoples experience only geunine Ford or Bosch leads are any good, and they generally only last around 40-50k, so to get 81k out of your originals you were doing very well.

Also reduce the plug gap from 1.3 down to 1-1.1mm.

Tim..

Reply to
Tim (Remove NOSPAM.

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