Common Symptoms of a BAD
Ford Coil-on-Plug Ignition Coils
This is not the most definitive list on the subject, but does cover the majority of symptoms I've seen on this type of Ignition System:

1.Misfire Codes that light up the CHECK ENGINE LIGHT (CEL) on your Instrument Cluster.
2.Misfire Codes: P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308.
3.Engine Misfire that DOES NOT light up the CHECK ENGINE LIGHT (CEL).
4.Smell of unburned gasoline coming out of the tailpipe.
5.Rotten egg smell coming out of the tailpipe. This is due to the unburned gasoline from the misfiring cylinder over loading the catalytic converter.
6.Really BAD gas mileage.
7.Lack of power as you accelerate the vehicle down the road.

 

What tools do I need?
A Scan Tool (Automotive Diagnostic Scanner) isn't needed to test the COP Ignition Coils on your Ford car or truck. The tests you're about to learn are all done without one. Now, what if you don't know which cylinder is the one misfiring? Don't you need a Scan Tool to find out? Well no, you can find out which one it is without a Scan Tool. You can perform the cylinder balance test yourself on your Ford car or truck, Test 5 will help you with this. You'll need:

 

yourself on your Ford car or truck, Test 5 will help you with this. You'll need:

1.An HEI Spark Tester.
This inexpensive Spark Tester is a MUST have tool to be able to correctly diagnose the Coil-on-Plug Ignition Coils on your Ford (or Mercury or Lincoln) vehicle with the info/tests in this article (don’t have an HEI Spark Tester? Need to buy one? You can buy it here: KD Tools 2756 Ignition Tester Calibrated For HEI Ignitions).
2.Battery Jump Start Cables.
3.LED Light.
To see what one looks like, click here: Abe's LED Light tool.
4.A helper.
a.You'll need someone to help you crank the engine while you perform the tests in the engine compartment.
5.A Repair Manual.
a.For whatever remove and replace info you'll need that is not covered by this article.

 

Circuit Descriptions of the C-O-P Ignition Coil Connector
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Next image OK, to test the Coil-on-Plug Ignition Coils on your Ford car or truck, you need to know what each wire (circuit) does in the connector. Here are the Circuit descriptions:

1.Circuit labeled 2:
Power (12 V) Circuit.
2.Circuit labeled 1:
Switching Signal Circuit.
You don't need to know the color of the wires for this test since the circuit descriptions (above) are shared by all of the eight Coil-on-Plug Ignition Coils on your Ford car or truck. So, whether you're testing the number 1 cylinder Ignition Coil or the number 4 cylinder Ignition Coil (or whichever Ignition Coil)... the above info applies.

To test these circuits, it's not necessary to unplug the Ignition Coil's connector. What I recommend you do is to test for each Signal with the connector connected using a Wire-Piercing Probe. This is the easiest and the most effective way of getting at the signals. If you need to see what this tool looks like, click here: Wire-Piercing Probe.

 

Before jumping into the tests... you'll need to first check that all of the Coil-on-Plug (COP) Ignition Coil connectors on your Ford car or truck are not broken and thus securely attached to their respective Ignition Coils. Broken? What I mean is this: Each connector has a plastic tab that locks the connector in place (onto the Ignition Coil). This locking tab prevents the connector from un-plugging itself from the Ignition Coil. And this tab breaks easily. Normally after someone has disconnected the Ignition Coil to replace it or replace the Spark Plug or replace whatever necessitates the Ignition Coil to be removed from its place.

 

This is a very common problem/cause of a Misfire Condition on these Ford COP Ignition Systems. This is what could be causing your Misfire problem and you can check this by gently pulling on all of the Ignition Coil connectors (without pressing their locking tab) to see if they'll come un-plugged.

If it comes un-plugged, well then you have found a problem that could very well be the cause of your Misfire condition. Repair it before continuing with the rest of the tests. If you do need to buy some of these connectors, you can buy them here: Pico 5713pt Ford Ign Coil Pigtail 2-Wire 99+

 

COP COIL TEST 1
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Next image If you're just coming into this page and have not read the 'First Things First' subheading in the previous page, please do so now. If you have, well then... this a pretty straight forward test, but one that has to be done with the HEI Spark Tester. Here are a couple suggestions that'll help you to avoid wasting money and time (by not replacing a good part):

1.Do not use a regular Spark Plug instead of a dedicated Spark Tester. Using a Spark Plug (instead of a Spark Tester) is the surest way to chase a ghost that'll have you spending your hard earned money on parts the car does not need.
2.Pulling the Ignition Coil off of its Spark Plug, as the engine is running, to see/hear if it's sparking is a major NO NO. A lot of folks do this and swear by it as being effective... nothing could be further from the truth. This method can ruin/fry the Ignition Coil and now you've got another problem on your hands.
3.I don't recommend using any other type of Spark Tester. Buy the HEI Spark Tester... not an imitation or something similar (don’t have an HEI Spark Tester? Need to buy one? You can buy it here: KD Tools 2756 Ignition Tester Calibrated For HEI Ignitions).
OK, now on with the show... I'm gonna' assume that you know which cylinder is the one that is misfiring or with the BAD Ignition Coil or Coils (but, if you don't know which cylinder is the one, go to TEST 5)... so then, the very first thing that has to be done is to:

1.Remove the Coil-on-Plug Ignition Coil that you know or suspect is misfiring/BAD.
2.Attach the HEI Spark Tester (or an equivalent Spark Tester) to the Coil-on-Plug Ignition Coil (as shown in the photos in the image viewer).
3.Attach the HEI Spark Tester to a good Ground point by using a Battery Jump Start Cable (my preferred method).
4.Have your helper crank the engine while you observe the Spark Tester.
5.After noticing the result, which will be either Spark or No Spark, disconnect the Spark Tester and put the Ignition Coil back in place.
6.Repeat the test for all of the remaining Coil-on-Plug Ignition Coils.
7.You're gonna' get one of two results: Spark or No Spark.

 

Interpreting the Results
If you got Spark, from all of the Ford car or truck Coil-on-Plug Ignition Coils... then the Ignition Coils are good. The cause of the Misfire is something else. Go to TEST 4.

If you got Spark, from some but NOT all of the Ford car or truck Coil-on-Plug Ignition Coils... then the ones that did not fire off Spark are probably BAD. To make sure you need to verify that the Ignition Coil (the one that did not Spark) is receiving 12 Volts and the Switching Signal. Go to TEST 2.

If you got NO Spark, from none of the Ford car or truck Coil-on-Plug Ignition Coils... then the cause of your Ford's NO START Condition is not due to the Ignition Coils. It is rare (next to impossible) for all of the Ignition Coils to go BAD at the exact same time. Testing this condition is beyond the scope of this article but possible causes could be a BAD Crankshaft Position Sensor, BAD Ignition Switch, etc.

 

COP COIL TEST 2
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Next image OK, you're here because in TEST 1 you got a NO SPARK result from one of several Ignition Coils. The next step is to verify that that Ignition Coil or Coils are receiving power.

Testing for Power can be accomplished by testing the COP Coils connected or disconnected to their connectors. The method I recommend to use is with them connected to their connectors and with a Wire-Piercing Probe (to see what this tool looks like, click here: Wire-Piercing Probe. Now, if you decide to unplug the connector to test the front of the female terminal (of the connector) for 12 Volts... be careful not to damage it.

1.Remove the Coil-on-Plug Ignition Coil that did not Spark and connect the HEI Spark Tester to it (although you're no longer testing for Spark, the Spark Tester must be connected just as a safety precaution).
2.The two wires in the Ignition Coil's connector are usually wrapped in black electrical tape (that probably has become as hard as plastic)... remove enough of this tape to expose the two wires for testing.
3.With the Ignition Coil connected to its connector.
4.Put the multimeter in VOLTS DC mode.
5.Probe the circuit labeled with the number 2 (see photo in image viewer) with the RED Multimeter Test Lead (using an appropriate tool to pierce the wire).
6.With the BLACK lead of the multimeter probe the BATT (-) NEGATIVE terminal.
7.Have your helper turn the key to the ON position.
8.You should see 11-12 Volts on your Multimeter, or if you're using a Test Light... the Test Light should light up.
If the Multimeter registered 11-12 Volts (or the Test Light lit up), then the Power Circuit is OK and is delivering voltage. The next step is to test the Switching Signal Circuit, go to TEST 3

If the Multimeter DID NOT register 11-12 Volts (or the Test Light DID NOT light up), then the Power Circuit has a problem. This result eliminates the COP Ignition Coil as the source of the Misfire Condition. The Power Circuit is shared by all of the COP Ignition Coils.

 

COP COIL TEST 3
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Next image OK, you're here because you have confirmed that the Ignition Coil is not Sparking and that 12 Volts are present. The next step is to verify that that Ignition Coil's is receiving the Switching Signal from the Fuel Injection Computer. We'll be using an LED Light.

Testing for the Switching Signal can be done with the Ignition Coil connected or disconnected to its connector. The method I recommend to use is with it connected to its connector and with a Wire-Piercing Probe (to see what this tool looks like, click here: Wire-Piercing Probe.

The other method is to unplug the COP Ignition Coil connector and insert the terminals of the LED into it. If you do it this way, make sure that whatever size terminal you insert into them does not open them up. If this happens, you are going to create yourself a major headache.

With the Coil-on-Plug Ignition Coil that did not Spark already removed and still connected to the HEI Spark Tester and to its connector:

1.Connect the BLACK lead of the LED Light to the wire labeled with the number 1. Again, I recommend using a Wire-Piercing Probe to do this, but whatever method you use... be careful.
2.Connect the RED lead of the LED the BATT (+) Positive terminal.
3.Have your helper crank up the engine as you observe the LED Light.
4.The LED Light should flash on and off the whole time the engine is cranking and also when it finally starts.
If the LED Light flashed On and Off, then the Switching Signal is present. This result indicates that the Coil-on-Plug Ignition Coil on your Ford car or truck is BAD and needs to be replaced.

If the LED Light DID NOT flash On and Off, re-check all of you connections and repeat the test again. If still no flashing On and Off, then this results eliminates the Ignition Coil as the source of the NO SPARK condition/Misfire, since without the Switching Signal the Ignition Coil will not work.

There are several possible causes for this that I've seen time and time again with the most common being: An open short in the wire that feeds the Switching Signal between the Fuel Injection Computer and the COP Ignition Coil. The second most common: A fried Fuel Injection Computer. Although testing these two conditions are beyond the scope of this article, you have at least eliminated the Ignition Coil itself as the cause of the problem.

 

COP COIL TEST 4
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Next image If all of the Ignition Coils fired off Spark in TEST 1 and yet your Ford car or truck is experiencing a Misfire Condition, then the most likely causes are: 1) the Spark Plug Boots and Spark Plugs have developed Carbon Tracks or 2) the Spark Plugs and Spark Plug Boots are swimming in engine oil or anti-freeze (from a leaking intake manifold gasket) or 3) both of the aforementioned conditions. All of these conditions are a very common occurrence in this type of Ford Coil-on-Plug Ignition System.

If the Spark Plug Boots and Spark Plugs are swimming in engine oil, it's usually due to the Valve Cover Gasket leaking oil into the Spark Plug Tubes. This oil will cause the Ignition System to Misfire and/or cause Carbon Tracks to form as the Spark cooks the oil. The Solution here is to replace the Valve Cover Gaskets along with the Spark Plugs and Ignition Coil Boots.

If the Intake Manifold Gasket (which is made out of plastic) is leaking anti-freeze into the Spark Plug Tubes... this will cause your Ford Car or Truck to Misfire. The Solution here is to replace the Intake Manifold Gaskets along with the Spark Plugs and Ignition Coil Boots.

In the image viewer you'll see what a Carbon Track looks like on the Spark Plug Boot and on the Spark Plugs. The next step is to remove the Spark Plugs and Spark Plug Boots to visually inspect them for Carbon Tracks and/or to see if the are all oil-soaked or anti-freeze soaked.

If the Spark Plugs are oil-soaked and/or anti-freeze soaked and/or with Carbon Tracks, you'll need to replace them all along with the Spark Plug Boots. Failure to replace one without the other will only make the Carbon Track return and/or continue to Misfire still.

 

COP COIL TEST 5
CYLINDER BALANCE TEST
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Next image As stated in the beginning of the article, you don't need a Scan Tool to find out which cylinder or cylinders are the ones misfiring. But, if you have one, read on anyway. This info will help you to add to your 'toolbox of know-how'.

The main reason why you should perform a Cylinder Balance yourself and not rely on a Scan Tool to identify the misfiring cylinders (on a Ford) is that in many cases it takes the Fuel Injection Computer too long to set the Misfire Code and a lot of times... it may not be the correct one. Therefore, knowing how to perform a simple Cylinder Balance test (with tools that are not going to break the bank) becomes important.

How is the Cylinder Balance Test Done?
What you're gonna' do is to unplug one Fuel Injector at a time to see if you can hear/feel a drop in engine RPM's and a drop in engine vacuum (as measured using a Vacuum Gauge). So, you're gonna' need a vacuum gauge. The Vacuum Gauge will help you to visually confirm the drop in engine RPM.

The test is done with the engine running. So you have to be careful. Take all necessary safety precautions and use common sense. Also, this method will set some Fuel Injector Codes that you'll have to erase after you get done. Alright, here's the procedure:

1.Connect the Vacuum Gauge to an available Vacuum Hose that has vacuum at engine idle. In the image viewer photo, the Vacuum Gauge is connected to the plastic vacuum line that feeds the EGR Vacuum Solenoid.
2.Start the engine.
3.Disconnect one Fuel Injector and notice if:
a.You can hear/feel a drop in the engine RPM's. and
b.See if the Vacuum Gauge needle drops.
4.Again, what you're looking for is if disconnecting the Fuel Injector causes a change in the hum of the engine (RPM drop) and a change in the Vacuum Gauge's needle.
5.Unplug and re-connect the same Fuel Injector connector as many times as you need to to get a result you're sure of.
6.After you're sure of your result, re-connect the Fuel Injector and go to the next one.
7.Repeat this with all of the remaining Fuel Injectors.

 

do you just want the link to where im getting all this info from?

 

haha that would have probably been easier to start

 

Ya i know it just got addicting... here it is Part 1 -Testing FORD Coil-on-Plug (COP) Coils.
there are about five different threads on this throughout the years, and most of the time its moisture under the boots...