My 2.0 Duratec has a fairly regular misfire, which I've been informed is potentially a dodgy coil pack and/or plug leads. But I've swapped them for what I would consider 'decent' replacements, and it hasn't helped.

Having said that, a lot of forum advice suggests that even new parts can struggle on the Duratec, so I was wondering whether there was anything I could do to test the coilpack or leads, say with a multimeter? My bike coilpacks had a specific resistance range that could be tested, is there similar for others?

I don't want to buy a third set of ignition parts if the problem is actually somewhere else.

It does have an engine light on, which is the EGR valve malfunctioning. I've cleaned it several times, but I think the EGR valve is a symptom of the misfire rather than the cause.

If you have got an egr fault it can give you misfires and lack of power issues !

Ford specified an excessively large spark gap that creates a very high ignition secondary that puts enormous stress on the insultation of the coil and plug leads. Ford subsequently reduced the specified gap but it still on the wide side.
Personally I always avoid Intermotor brand leads as the ones they supply for Rover K engines are too long for the plug wells.

Heres is the official NGK method of checking spark plug leads for continuity https://www.ngk.de/en/technology-in-detail/ignition-cables/diagnosis/testing-of-ignition-cables/


Checking the leads for shorts is also easy you just need a pices of wire connected to a ground I use a normal 12v test lamp (not LED type) because it has good insulation and a crocodile clip at the other end. With the engine running give the leads a gentle spray of water and run the pointed end of the test probe along the plug lead looking for leaking sparks.

You can also stress test the coil and lead using an adjustable spark gap tester

Laser 5655 Adjustable Spark Tester

or

Adjustable Ignition Coil Tester Spark Circuit Tester Securely Avoid Fire Tool


Beyond that you would need an oscilloscope to do more tests.

Many thanks BT, that's the sort of stuff I was after. I went for the Laser one as it's from a uk seller.

Ian, I've ordered a blanking plate for the EGR. Even if I don't leave it in place at least I can find out whether the EGR is a cause or a symptom.

leads were a very common failure on these engines caused by folk pulling the leads rather than the caps to get them out the hole, problem is if you had this issue it will take out the plugs as well. removes the plugs and look for arcing lines on the ceramic caused by hot spark, if theres lines it will be missfiring

Video 4 on this page shows how to check for broken down plug wire insulation.

http://www.wikihow.com/Test-Spark-Plug-Wires

quote:

---

Originally posted by hizzi
leads were a very common failure on these engines caused by folk pulling the leads rather than the caps to get them out the hole, problem is if you had this issue it will take out the plugs as well. removes the plugs and look for arcing lines on the ceramic caused by hot spark, if theres lines it will be missfiring

---