No spark to cylinder 3

[alamogeorge]

I hate to admit it but I thought I could gently spray the engine at the car wash without using any pressure....NOT. I guess the old "I can get away with it" bit me in the ass.

I have a 2002 3.0 FFV. It started running rough and the check engine light began flashing. Drove it for a bit and it didn't clear up. I pull each plug wire off of the coil pack one at a time and I have no spark from the coil on #3.

I ohmed the primary and secondary on the coil pack and it all checked good.

I put compressed air to all of the spark plug holes, even though I know that's not the problem since spark isn't even making it that far.

I guess my next question would be, where does the coil pack get spark from? OR...could the coil pack still be bad even though it ohms out? OR....am I totally off base and need to be looking at something else.

 

[Rearanger]

Have you given it some time to totally dry out? Could be just arcing from dampness on wires, etc. I'd pull connectors off and dry them individually.

 

[alamogeorge]

It's been a few days now. I'm pretty sure that it's not the wires or plugs since there is no spark coming out of the coil at #3. I ohmed the primary and secondary of the coil.

I can't seem to find where the coil gets the spark to begin with. Any ideas?

 

[Rearanger]

I ohmed the primary and secondary of the coil.

What resistance did you get?

I can't seem to find where the coil gets the spark to begin with. Any ideas?

Not sure I understand your question. The coil gets it's "spark" from the 12 volt primary, the primary is shut on/off by the ECU which creates the secondary voltage to the plug. Not exactly sure but I believe you should be getting 12v constant at the primary with KOEOff, as you turn the engine over the ECU closes the ground which collapses the primary and creates secondary plug voltage. You can connect a 12v test light to the + primary and then ground it, as you turn the engine over the light should go off/on. If you have 12v at primary then the coil is probably bad, no switching of the light and it's an ECU problem or bad connection, but since it's only on #3 I doubt ECU. Can you switch coils or is this one big coil pack?

 

[alamogeorge]

Well, it's that simple. Bad coil pack. I don't remember the risistance of hand but it was the same as the new one.

They are all fed by the primary and then switched between the pairs. In other words, they all get the same 12v. If one has it then they all have it. It is then switched between 1-5, 2-6, and 3-4. Since 4 had it but 3 didn't it meant that something was preventing 3 from getting it. Something inside.

Anyway, I found this excellent coil pack troubleshooting article. Makes a lot of sense once you know what it is supposed to do. More to it than just ohming the pairs or the primary.

http://easyautodiagnostics.com/ford_coil_pack/ford_coilpack_tests_1.php

 

[Rearanger]

Glad you figured it out. Basics, basics, basics is key. From memory even my Ford FSM doesn't require any special tools. Thanks for the link, that's a clearly written and illustrated article. It looks like you could even use a spark plug to the test individual coil output instead of buying the KD tool you linked to.