Test methods for individual coil packs - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

hutcho3 · 06-11-2009, 17:42

Can anyone describe some ways to test individual coil packs?

I was getting a misfire on cylinder 4. I looked at the spark plugs and they looked like they hadn't ever been changed (179000 miles later)! Gap was around 0.065-0.080", and very corroded plugs. The plug in cylinder 4 and 6 had a little oil on the threads, so I tightened the valve cover bolts, hoping that'll take care of it. Also, the boot had a little what looked like burnt oil going up the side, and the spring inside had some brown goop on it. After changing the front 3 easy plugs, boots and springs, engine runs much better but still has a couple hick-ups at idle from time to time. I'm going to pull the intake manifold off and replace the back 3 plugs also, and while I've got it apart I'd like to check the coil packs. I've got a multimeter, but I'm new to it, and don't know much about ohm testing.

Thanks for the help!

2000 Ford Taurus Sedan
3.0L Duratec DOHC

**jwko** · 06-12-2009, 00:27

Testing

3.0L (VIN S) Engine
Primary Winding Resistance

1.Turn the ignition OFF .
2.Disconnect the negative battery cable.
3.Disconnect the wiring harness from the ignition coil.
4.Check for dirt, corrosion or damage on the terminals and repair as necessary.
5.Measure coil primary resistance between ignition coil pin 4 (B+) and pins 1 (coil 2), 2 (coil 3) and 3 (coil 1).
6.Resistance should be 0.3-1.0 ohms. If resistance is out of specifications, replace the coil pack. If resistance is within specifications, proceed to secondary windings testing.

Secondary Winding Resistance

1.Measure coil secondary resistance between the corresponding spark plug wire towers on the coil.

Coil 1-cylinders 1 and 5
Coil 3-cylinders 2 and 6
Coil 2-cylinders 3 and 4

2.Resistance should be 12.8-13.1 kilohms. If secondary resistance is not within specification, replace the coil pack.

**tbird100636** · 06-12-2009, 19:52

Quote:

Originally Posted by hutcho3

Can anyone describe some ways to test individual coil packs?

I was getting a misfire on cylinder 4. I looked at the spark plugs and they looked like they hadn't ever been changed (179000 miles later)! Gap was around 0.065-0.080", and very corroded plugs. The plug in cylinder 4 and 6 had a little oil on the threads, so I tightened the valve cover bolts, hoping that'll take care of it. Also, the boot had a little what looked like burnt oil going up the side, and the spring inside had some brown goop on it. After changing the front 3 easy plugs, boots and springs, engine runs much better but still has a couple hick-ups at idle from time to time. I'm going to pull the intake manifold off and replace the back 3 plugs also, and while I've got it apart I'd like to check the coil packs. I've got a multimeter, but I'm new to it, and don't know much about ohm testing.

Thanks for the help!

2000 Ford Taurus Sedan
3.0L Duratec DOHC

You shouldn't have to pull the intake to do the back 3 plugs. Just remove the R. cowl screen, the plastic panel the screen sits on, then working from the right side of the car you can get at the coils and plugs. Those individual coils did have some issues.

**tbird100636** · 06-12-2009, 19:54

Quote:

Originally Posted by jwko

Testing

3.0L (VIN S) Engine
Primary Winding Resistance

1.Turn the ignition OFF .
2.Disconnect the negative battery cable.
3.Disconnect the wiring harness from the ignition coil.
4.Check for dirt, corrosion or damage on the terminals and repair as necessary.
5.Measure coil primary resistance between ignition coil pin 4 (B+) and pins 1 (coil 2), 2 (coil 3) and 3 (coil 1).
6.Resistance should be 0.3-1.0 ohms. If resistance is out of specifications, replace the coil pack. If resistance is within specifications, proceed to secondary windings testing.

Secondary Winding Resistance

1.Measure coil secondary resistance between the corresponding spark plug wire towers on the coil.

Coil 1-cylinders 1 and 5
Coil 3-cylinders 2 and 6
Coil 2-cylinders 3 and 4

2.Resistance should be 12.8-13.1 kilohms. If secondary resistance is not within specification, replace the coil pack.

This test doesn't apply, as the 2000 Taurus/Sable Duratec had individual coils. They went back to a coil pack in 2001.

**jwko** · 06-12-2009, 23:32

Thanks for the heads up tbird.

I've had no luck finding testing procedures for the coil on plug setup.

**tbird100636** · 06-14-2009, 21:21

No resistance tests, you first make sure there isn't any Crank Sensor codes. Then, with the coil disconnected you put a test light between the connector terminals and crank the engine (Remember to disable the fuel system first). The test light should flash while cranking. Next reconnect the coil connector. Remove the coil, install a spark tester, and again crank the engine. You should have spark.

doc_aoc · 06-19-2009, 20:03

Quote:

Originally Posted by jwko

Testing

3.0L (VIN S) Engine
Primary Winding Resistance

1.Turn the ignition OFF .
2.Disconnect the negative battery cable.
3.Disconnect the wiring harness from the ignition coil.
4.Check for dirt, corrosion or damage on the terminals and repair as necessary.
5.Measure coil primary resistance between ignition coil pin 4 (B+) and pins 1 (coil 2), 2 (coil 3) and 3 (coil 1).
6.Resistance should be 0.3-1.0 ohms. If resistance is out of specifications, replace the coil pack. If resistance is within specifications, proceed to secondary windings testing.

Secondary Winding Resistance

1.Measure coil secondary resistance between the corresponding spark plug wire towers on the coil.

Coil 1-cylinders 1 and 5
Coil 3-cylinders 2 and 6
Coil 2-cylinders 3 and 4

2.Resistance should be 12.8-13.1 kilohms. If secondary resistance is not within specification, replace the coil pack.

When you say "pin 4 (B+) which pin is that? Is it the forth pin going left to right?

Is it possible for the coil pack to still be bad if it passes these test procedures?

Just wanting to check since this is going to be the 3rd pack I have replaced in this car over the past 5 years!