If your 4.6L Ford car (or pick up or SUV) equipped with the two coil pack ignition system is misfiring (P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308), this is the article that will help you to troubleshoot those misfire codes.
The two most common problems, with this type of ignition system is either a bad ignition coil or bad spark plug wires, and this article will help you to troubleshoot both.
CIRCUIT DIAGRAM: The following circuit diagram may be of help: Ignition System Wiring Diagram (1997-1999 4.6L Ford F150, F250).
You can find this tutorial in Spanish here: Cómo Probar Las Bobinas De Encendido DIS (4.6L Ford V8) (at: autotecnico-online.com).
Important Tips And Suggestions
IMPORTANT: Before you jump into the tests, please read the following tips and suggestions:
TIP 1: I'll use the phrase ‘Paired Cylinders’ quite a bit. To successfully diagnose the misfire or ignition system on your 4.6L Ford vehicle, it's important that you understand what this means, so be sure and read the section ‘Coil Pack Basics’ before you start testing.
TIP 2: Think and breathe SAFETY the whole time you're physically doing these tests, since some of these tests require that you crank the engine.
If a helper is gonna' help you, have him or her wait outside the vehicle till you're ready to have him or her crank the engine (as you're setting up the test).
TIP 3: You'll notice that the photos and the testing instructions call for an HEI spark tester. If you don't have one, don't panic, you can use any other type of spark tester (although the results may not be as accurate). If you want to know the reason for the fixation on the HEI spark tester, go to: The HEI Spark Tester (The Best Spark Tester On The Market) (at: easyautodiagnostics.com).
Coil Pack Basics
What's gonna help you to easily find the bad coil pack or the root cause of the misfire on your 4.6L Ford car or pick up (or SUV), is to know that each coil pack is made up of 2 individual ignition coils.
Here are some more specific details:
- Each individual ignition coil (within the pack) has two towers.
- This is the reason why each coil pack has a total of 4 towers.
- Two towers fire spark to 2 different cylinders at the exact same time.
- The cylinders that get spark at the exact same time are known as ‘Paired Cylinders’.
- Each coil pack has three wires coming out of its electrical connector.
- One wire is the power source (12 Volts).
- The other 2 wires provide the switching signal for each ignition coil.
- The switching signal is what activates the individual ignition coil (within the pack) to fire off spark.
- The coil pack on the passenger side of the engine feeds spark to:
- Cylinders 1 and 6.
- Cylinders 3 and 5.
- The coil pack on the driver side of the engine feeds spark to:
- Cylinders 4 and 7.
- Cylinders 2 and 8.
- The most important thing to remember is that the two cylinders that get spark at the exact same time are referred to as ‘Paired Cylinders’ throughout the article.
Keeping the above info in mind, as you test the ignition system, will help you to easily diagnose the root cause of the misfire. Now, don't let all of this info intimidate you, the article should walk you thru' the whole testing process without too much difficulty.
Where To Buy The Ignition Coil Pack And Save
The following links will help you comparison shop for the original Motorcraft and aftermarket ignition coil packs:
Not sure if the above ignition coil packs fit your particular Ford? Don't worry, once you get to the site, they'll make sure it fits. If it doesn't, they'll find you the right one.
Circuit Descriptions Of The Coil Packs
Each coil pack's electrical connector has three wires coming out it. In the illustration above you'll notice that the coil packs connector has 3 male spade terminals. Each terminal is labeled with a number (1, 2, or 3).
Here are the job descriptions of the wires that connect to these coil pack male spade terminals:
Passenger Side Coil Pack:
- Wire labeled with the number 1 feeds the switching signal for cylinders 1 and 6.
- Wire labeled with the number 2 feeds 12 Volts to the coil pack.
- Wire labeled with the number 3 feeds the switching signal for cylinders 3 and 5.
Driver Side Coil Pack:
- Wire labeled with the number 1 feeds the switching signal for cylinders 4 and 7.
- Wire labeled with the number 2 feeds 12 Volts to the coil pack.
- Wire labeled with the number 3 feeds the switching signal for cylinders 2 and 8.
