How To Test The 2 Coil Packs (Ford 4.6L V8)

TEST 1: Checking For Spark

The very first thing you need to do is to find out which cylinder or cylinders are the ones that are misfiring (‘dead’). To find out, you'll need to do one of two things: Check for misfire trouble codes (P0301, P0302, P0303, etc.) or do a cylinder balance test.

If you have a cylinder misfire but no misfire codes stored in the computer's memory, then I suggest you take a look at this section: Finding the ‘Dead’ (Misfiring) Cylinder.

OK, in this test, you're gonna test the spark plug wire of the cylinder that's misfiring with a spark tester.

You'll notice that the photos and the testing instructions call for an HEI spark tester. If you don't have one, you can use any other type of spark tester (although the results may not be as accurate). If you want to know why I recommend the HEI spark tester, see: The HEI Spark Tester (The Best Spark Tester On The Market) (at: easyautodiagnostics.com).

If you have identified more than one cylinder as misfiring, you'll need to test one spark plug wire at a time and you'll start by:

1. 1

   Locate the first misfiring cylinder you're gonna' test. The illustration in the previous page will help you identify the number of the cylinders. Remember that P0301 means cylinder #1 misfire, P0302 means #2 misfire, P0303 means #3 misfire and so on.

2. 2

   Now, disconnect the spark plug wire from the spark plug and connect the HEI spark tester to it (see photo above).

3. 3

   Using a battery jump start cable, Ground the HEI spark tester to the battery negative (-) terminal.

4. 4

   Now, have your helper crank the car (or pick up or van) as you watch the HEI spark tester.

5. 5

   You'll get one of two results: the HEI spark tester will spark or not spark.

6. 6

   Repeat steps 1 thru' 4 on the other spark plug wire that the misfire code has identified as misfiring.

OK, let's take a look at what your test results mean:

CASE 1: You got spark from the spark plug wire: this confirms that spark is reaching the spark plug. This also confirms that the spark plug wire is OK.

If the cylinder is still missing, I suggest testing the following:

• That the spark plug and the spark plug wire do not have carbon tracks.
• That the spark plugs ceramic insulator is not broken or cracked.
• That anti-freeze or engine oil is not leaking into the spark plug well.

Any of the above three conditions will cause a misfire.

CASE 2: You got NO spark from the spark plug wire or wires: this test result doesn't condemn the coil pack or the spark plug wires as bad yet. The next step is to test for spark directly on the coil pack towers of the wire or wires that did not spark. Go to: TEST 2: Checking For Directly On The Coil Tower.

Here's why: The next step is to eliminate the spark plug wires as bad. spark plug wires do go bad and could make you think the coil pack is the one that has failed.

TEST 2: Checking For Directly On The Coil Tower

In this test step, you're gonna' test for spark directly on the coil pack tower of the spark plug wire or wires that did not spark in TEST 1.

Depending on the spark result of this test, you'll be able to say the coil pack is bad or continue on to the next step.

If you're testing more than one coil pack towers for spark, you'll need to test each one at a time. Alright, this is what you'll need to do:

1. 1

   OK, disconnect the spark plug wire (high tension wire) from the coil pack and place the HEI spark tester directly on the coil pack tower (see photo).

2. 2

   Now Ground the spark tester using a battery jump start cable directly on the battery negative (-) terminal.

3. 3

   When ready have your helper crank the engine as you eyeball the HEI spark tester, you'll see one of two results: spark or no spark.

4. 4

   Repeat steps 1 thru' 4 on the other coil pack tower (if applicable).
   
   

There are three different test result scenarios for TEST 2:

• You're only testing 1 misfiring cylinder.
• You're testing 2 misfiring cylinders and these are ‘Paired Cylinders’.
• You're testing 2 misfiring cylinders and these ARE NOT ‘Paired Cylinders’.

TESTING 1 MISFIRING CYLINDER:

CASE 1: You got spark from the coil pack tower: this spark test result tells you that the spark plug wire (high tension wire) is FRIED. Replace all of the spark plug wires as a set.

Here's why: This (spark plug wires not delivering spark) does happen quite a bit. As you're already aware, spark plug wires don't last forever and when they go bad, they stop transmitting spark. If the spark plugs are as old as the cables, replace them too.

CASE 2: You got NO spark from the coil pack tower. This confirms that the coil pack is bad if the other 3 coil pack towers are sparking when tested with the spark tester.

TESTING 2 MISFIRING CYLINDERS THAT ARE ‘PAIRED’:

CASE 1: You got spark from 1 coil pack tower but not the other. This tells you that the coil pack is bad. Replace the coil pack.

CASE 2: You got NO spark from both coil pack towers. You can't condemn the coil pack as junk yet. The next step is to see if that specific ignition coil within the coil pack is receiving the switching signal or not.

If you got no spark for cylinders #6 and #1 (passenger side coil pack), go to: TEST 3: Checking The Switching Signal For Cylinders 6 and 1.

If you got no spark for cylinders #3 and #5 (passenger side coil pack), go to: TEST 4: Checking The Switching Signal For Cylinders 3 and 5.

If you got no spark for cylinders #7 and #4 (driver side coil pack), go to: TEST 5: Checking The Switching Signal For Cylinders 7 and 4.

If you got no spark for cylinders #8 and #2 (driver side coil pack), go to: TEST 6: Checking The Switching Signal For Cylinders 8 and 2.

Here's why: Keeping in mind that each ignition coil, within the coil pack, receives an individual activation signal (called the switching signal) to start sparking away, the next step is to test for this switching signal. If this signal is present, then the coil pack is really and truly fried.

CASE 3: You got spark from both coil pack towers: this spark test results let you know that the spark plug wires are bad. Replace the spark plug wires.

TESTING 2 MISFIRING CYLINDERS THAT ARE NOT ‘PAIRED’:

CASE 1: You got spark from both coil pack tower: this spark test result tells you that the spark plug wires (high tension wires) are FRIED. Replace all of the spark plug wires as a set.

Here's why: This (spark plug wires not delivering spark) does happen quite a bit. As you're already aware, spark plug wires don't last forever and when they go bad, they stop transmitting spark. If the spark plugs are as old as the cables, replace them too.

CASE 2: You got NO spark from both coil pack towers. This confirms that the coil pack is bad. Replace the coil pack.