JCR 56

PO356, some possible causes

Short to voltage or ground on COP driver circuit.
Open on COP driver circuit.
Bad coil.
Faulty PCM.
That's a few causes to look at, but of course not all.

BigEd54

The title of the error code tells ya what it is: "ignition coil F primary/secondary circuit is malfunctioning"

I'd swap the COP again. Maybe you got a bad one. Also check the wire harness and connector.

Edit: found this info in a thread on 2004-2008 models:

white89gt

Get a NOID light, or rig up a 12V halogen bulb and see if you have pulsing at the harness for cylinder 6. Also check injector pulse.

In 5 minutes I diagnosed a bad coil harness on an Escape. Busted wire inside the rubber insulation caused the misfire.

pas

Thats where i'm leaning. I checked power at both cop and injector and power is good. I used screwdriver as stethoscope, fuel injector 6 only clicks once every 2-3 seconds while the others constantly pulse. I had to order motorcraft fuel injector. No one had it locally. I'll update once i get injector in.

Thanks

mbb

Simply swapping injector and cop with one from a working cyl is a pretty definitive check too.

Advice......clean around all injectors on rail good first before changing. Expect all of them to come out of manifold. They seat loose in manifold, tight in fuel rail. Dont want dirt falling into manifold hole. Maybe compressed air good enough, maybe not for caked mud.

pas

Actually I already lifted rail. They all stayed in manifold. So I didn't want to start moving stuff around. I have a feeling this is the first time rail was lifted. I got truck with 110k 10yrs ago. Now it has 197K

BigEd54

Why/how would bad injector throw coil circuit error?

pas

I agree and i'm open to suggestions. As I stated I checked power and ground to both cop and injector and it was fine. I even disconnected battery because from what I know vehicles shut down fuel injectors if there is a spark problem. I've put in 3 brand new cops and a new motorcraft plug in same cylinder 6. Two were in my garage from ebay that I keep spares of and the last one was genuine motorcraft with no change. I used screw driver as stethoscope and injector 6 only would click once every 2-3 seconds while all the others pulse rapidly. With a reset computer i'm not sure how quickly it would shut down injector but I immediately put screwdriver on injector after disconnecting battery/ reconnecting battery and restarting truck.

Is it possible computer shut down injector that quickly? Does a shutdown injector only click once every 2-3 seconds? Let me know.


I've never had this issue. Usually when I get a circuit error I just change cop check plug and all is good. Not this time

Thanks