Ignition coil resistance questions
 

I have no. 4 and 5 plugs misfiring. I haven't checked my plugs yet because they were changed by the local ford dealership about 1,500 miles ago. I checked the resistance of both coil packs. According to this book i have the Secondary resistance should be between 6.5 to 11.5 K ohms. and on my passenger side coil I'm getting 12.48 and 12.46 ohms and on the driver side i'm getting 12.69 and 12.65 ohms. Just wondering if i should change my coils or check the wires and plugs.

Taking resistance readings for coils is usally a waste of time except to check for gross opens or shorts.

A lot depends on what engine you have, which you didn't bother to identify.

Steve

Sorry, I knew i meant to type somethin else. It's a 98 f-150 4x4 with a 4.6
If I do need to change my coil packs should i go back with motorcraft or would msd be a better choice. Any better performance or are they about the same?

You haven't given any information as to WHY you're even putzing around with the ignition system.

Are you bored with too much time on your hands or does your engine have an actual problem that you're trying to address?

Steve

I have a missfire on #4 and #5. Someone told me that since my plugs were just changed to check my coils.

I would check the wires. Possibly a bad connection at the plugs.

I changed my plugs and checked the wires. All wires seemed to be fitting tight around the plugs. I can still smell gas out the exhaust pipe. Should i change my coil packs now. I figured if i change them I'll buy wires also.

Get a spark tester, cheap at autozone, and check the spark at each plug wire.

I bought a spark tester. The guys at autozone looked at me like i was crazy and said the didn't know what i was talking about. I found one at sears looks like my no. 5 wire isn't firing at all. I'm going to change my wires. I think I may change my coils also.

I was going to buy the coil packs and wires from the local ford dealer. They wanted 137.00 for the coil packs and 154.00 for the wires. I looked on this discountfordparts.com they have the coils for 68.00. What's the diff. are the ones from discount ford parts remanufactured?

I'm not sure about discount ford parts but try Mike @ directfordparts.com they are a dealership and I believe the prices may be as good or better. You can call him at 1-800-532-0819

I knew I should have took take domain name also.


These are new OEM parts, well the ones I would sell you would be.

Can't speak for anyone else, but I try and give FTE members the best price I can and still make a few bucks.

Ed

www.discountfordpartsaty2kford.com

ignition coils
 

I would like to know if anyone knows how to check ignition coils on 2005 F150 5.4 engine to see if they are good or bad while they are still on engine? Can you check them with a multimeter? I would rather check them before paying 50 bucks apiece. any help will be greatly appreciated. Thanks

I can attest from personal experience a resistance check of the COP's is NOT effective! Recently had a #3 misfire and having just recently replaced the plugs (Motorcraft ONLY!) and COP's (Granetelli) I thought it was simply a bad plug or COP. Quick resistance check suggested coil was NOT bad so off to more knowledgable people.

It was suggested I simply remove the COP but leave it connected to the harness and crank the engine with the COP lead close to a grounded point. If it threw a spark it was good, if not it was defective-simple as that. This alone told me the #3 COP was defective so it was replaced---runs fine now.

FWIW Ed the Parts Guy has GREAT pricing for anything OEM!! IIRC my local dealer will sell the COP's for like $52 each but doesn't include the boot--typically about $8 each. Granatelli sells the whole 8 cylinder kit including boots and terminals plus guaranteed voltage for $200. With a one year warranty this seemed like the best deal money-wise---doing the math its not tough to see this can be a good way to go.

Steve is right about resistance checks. The same thing goes for ECT sensors. You can check the resistance, but what good does it do you when the PCM is looking at VOLTAGE not resistance to determine when to go into closed loop. A scan tool is the correct way, but if you don't have one you can have an assistant start the engine and go into D and bring RPM up to about 2500 with E and foot brakes applied. You pull off COP and injector connectors one at a time and put them back in place after each is tested. When the connector is removed the engine speed should drop slightly and the motor should shake somewhat. This means this COP or injector is good(you have created a misfire by removing the connector). If there is NO CHANGE you have found a COP or injector that isn't working and you swap out the appropriate part(the misfire already exists in this case). Most of the time it is the COP. The injectors are much more reliable than the COPs.