How to? Test a coil...

[underthehood]

How do you test a coil to see if its bad? with a meter?

[SC Cheesehead]

How do you test a coil to see if its bad? with a meter?

What type of problems are you having?

[Blackened300a]

It requires a special tool to test it under load conditions. A coil could idle great but start missing under a load.
You'll have to bring it to a Ford dealer to have them tested.

[fastblackmerc]

It requires a special tool to test it under load conditions. A coil could idle great but start missing under a load.
You'll have to bring it to a Ford dealer to have them tested.

Or replace them all.

[underthehood]

my car was shuddering at low rmp's when i slowly got on the gas. i changed all of the spark plugs, and one of them had a small amout of oil or gas on the threads. So i figured just change that coil, maybe the oil or gas was because it wasn't firing. All the other spark plugs were fine. did all that and the car seems to be running fine so far. Have only had it on the rode for 10min since i changed the plugs and 1 coil though.

[RacerX]

The oil may be coming from between the valve cover and head. There are rubber seals that don't always seal perfectly. Double check all the valve cover bolts in that area also. Clean off the plug and cop boot end with brake cleaner. (May need HEI Spark Tester)

From a F150 site:

"with an Ohm meter and the coil on plug pack out of the truck...

Check the Primary circuit by simply taking the pos test lead and attach/touch it to one connector terminal and at same time attach/touch the neg test lead to the other. Measure the ohms and ensure you are seeing at most 5.5k Ohms


Also check the secondary circuit of the Coil on plug pack by touching the pos lead to one of the primary pins and the neg lead to the spring in the boot of the pack. Measure the ohms and ensure that .5500 Ohms.

Primary 5.500 k-ohms
secondary .55 ohm

this will work is the COP is dead....not one that is intermittent or starts acting up after it gets heated up or failing under load. FOrd makes a nice diagnostic tool that can diagnose problems like this."

[Marauder Rick]

I was gonna say put your tongue on the coil and have a friend crank up the car. If it does NOT shock the ever livin **** outta you.....then its bad. :lol:

[RacerX]

:D I remeber being about 10 and helping my dad with his 351 Gran Torino. Had me turn the engine over and he was touching the distributor or some such and after I figured out I hadn't killed him, I just about peed myself laughing so hard from the way he had jumped and screamed!

[WI Fordguy]

That's the side of the road way to check for a misfire in your 70 Bronco. Ask me how I know. Hurts like hell don't it? Damn long tubes burning through my plug wires.

[Blackened300a]

:D I remeber being about 10 and helping my dad with his 351 Gran Torino. Had me turn the engine over and he was touching the distributor or some such and after I figured out I hadn't killed him, I just about peed myself laughing so hard from the way he had jumped and screamed!

My cousin did that to a mechanic working on a MSD box. His hair stood up. :D

[underthehood]

ya im electrician i get shocked enough. dont need it from my car.