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How to Tell Which Coil Pack Is Bad on a Ford F150? – Easy Way!

Have you ever considered how to tell which coil pack is bad on a Ford F150? Well, if so, then this blog will indeed guide you. 

To figure out the bad coil pack on your Ford F150, you can carry out some tests. The easiest one is the coil exchanging method. You can also test the coil windings, and do advanced spark test to find the bad one.

So, to help you find the bad one, our experts have covered all the crucial topics to aid you with the best solutions.


What’s an Ignition Coil, and How Does It Work? 

When a car’s battery gives out 12 volts, the coil converts it into approximately 45,000 volts before supplying it to your engine’s spark plugs. 

So, an ignition coil is a wire that turns around like a transformer with a filled insulator. A spark coil or an ignition coil works when the coil gets induced in your vehicle’s ignition system. 

The entire ignition coil is designed and surrounded with copper wire. Inside the coil, you’ll find a secondary winding, and it’s generally a smaller coil wrapped up with a few thousand turns.


What’s an Ignition Coil Pack?

It’s a transformer that takes in low voltage from the battery and then enhances it to an extent where there’ll be a spark to bridge the plug’s aperture. This bridging sparks the air and fuel in the engine’s cylinder.

And the most significant reason they are called coil packs is that they are combined into side A and side B coils.

So, an ignition coil in a coil pack always fires two cylinders at the same time.

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To make it simple, the coil pack of a 4-cylinder engine consists of two ignition coils. The side A of the coil pack will ignite cylinders 1 and 4, and side B will ignite cylinders 2 and 3.

However, if you have a V8 then you’ll require two coil packs with a total of 4 ignition coils. So that each ignition coil can ignite two cylinders. Similarly, for a V6 engine you’ll need a coil pack with 3 ignition coils.


How Does an Ignition Coil Pack Work?

Inside every ignition coil, there are three main coil types. The primary winding, the secondary winding, and the iron core.

So, when the voltage enters the primary winding, it turns the iron core into a powerful electromagnet. The lines of magnetic force surround the iron core and then develop the secondary winding. 

After that, the voltage is switched off from the ignition coil. This is either done by the contact breaker, the ignition module, or the ECU.

During this phenomenon, the magnetic fields collapse, and the lines quickly return to the iron core. 

So, at this time, these fields push along the electrons (negatively charged particles) to the secondary winding, increasing the voltage, which pushes the current with significant force to the spark plug.


Is Ignition Coil and Coil Pack the Same Thing? 

They do serve the same basic purpose, but they are not the same thing. The coil pack is a new way to start the new generation of cars.

There was a time when older cars used to have ignition coils that supplied high voltage to spark up the ignition. 

Therefore, spark plugs needed a lot of high voltage to work. The distributor then sent the spark to each of the plugs in turn. However, modern cars don’t have a distributor anymore. 

Instead, the coil pack is connected either with recent configurations or a traditional plug wire to the spark plug.


What Are the Common Symptoms of Bad Ignition Coil on a Ford F150?

When the ignition coil fails in your Ford F150, it’ll make the engine misfire. So, to confirm this issue, you can conduct a few tests by connecting the OBD2 scanner to your F150. 

Check Engine Light Is On and PO300X Error Code: If you see an error code, then it means that the engine isn’t firing right. Below are some of the error codes that you need to know.

DTC (Diagnostic Trouble Code) indicates random cylinder misfires and can happen for many reasons. So, an expert mechanic can help you with this issue.

The X stands for the number of cylinders. Here’re two examples of this code:

  • PO301: It indicates that cylinder 1 of your F150 has misfired, and faulty spark plugs or engine compressions may be responsible for this.
  • PO302: It indicates that cylinder 2 of your vehicle has misfired, and faulty spark plugs or engine compressions may be responsible. 

Notice the last two digits of both these codes refer to the number of cylinders facing the issue. 

Change of Speed Is Poor: If the engine’s ignition coils don’t work right, the engine won’t be able to run your vehicle. When you press the gas pedal, the vehicle may not move right away, and it can also take quite a bit of time to reach your speed. 

Fuel Efficiency Is Poor: Ford F150s with bad ignition spark plugs or coils often consume a lot of fuel. If your car is getting less gas mileage, it’s time to check the spark plugs and the ignition coils.

The Engine Takes a Lot of Time to Start: When your engine’s ignition coils are non-responsive or damaged, it’ll take time for your engine to start and respond. Therefore, to get your F150 moving, the ignition system will have to work a lot harder.

Difficulty in Getting It Started: The F150s may resist starting if your ignition coils break. It simply means that the spark coils won’t be able to make the right sparks because there isn’t enough ignition energy.

Bad Smell of Unburned Gasoline From Tailpipe: A bad smell is also a significant sign of a bad ignition coil. When unburned gasoline enters the exhaust system, this can severely overheat your car converter and even cause a meltdown.


How to Test a Bad Coil Pack on a Ford F150?

Here are some methods to test and find the bad coil pack or coil-on-plug on an F150.

Method 1: Coil Exchange

Replace your ignition coil with an existing good ignition coil in the Ford F150. So, for instance, if a misfire takes place on any cylinders, simply replace the ignition coil from another cylinder.

Even if you get any code reader, you can easily clear the engine codes without challenge. 

However, if you still get misfires from your cylinders, then it’s not the faulty ignition coil. Instead, it can be an Ignition Module fault, and you need to consult with an expert to help you with this.  

Method 2: Windings of the Coil

Testing the coil’s windings for resistance can bring in potential issues. The primary and secondary windings of each ignition coil are wrapped around each other.

Therefore, check the vehicle’s maintenance manual for the correct resistance readings for the main and secondary windings. Here is how it goes –

  • Connect your multimeter’s negative and positive leads.
  • Double-check to see if you placed the terminals correctly depending on the coil’s design.
  • Check the multimeter reading and compare both the secondary and primary winding resistance parameters.

Method 3: Advanced Spark Test

Even when your ignition coil fails, it can still run the vehicle. However, you’ll notice frequent misfires, especially when you accelerate or your F150 is under load. 

So, you must take an advanced spark test and analyze your coil to detect the issues causing these problems.

You can also consult with an expert to give you the best advice regarding the advanced spark test.


What Is the Wasted Spark Ignition System?

This is an ignition system type primarily used for in a few four-stroke cycle internal combustion engines. And the reason it’s called a wasted spark ignition is because of the dual fire ignitions.

In this system, these spark plugs ignite in pairs with one plug in the cylinder’s exhaust stroke and the other in the compression stroke. 

Wasted sparks are very important because it compresses the igniter and the distributor to a more compact package.

Moreover, the wasted spark ignition has no oil seals, distributor caps, gears, or friction. Yet, it can easily handle the ignition timing, and that’s because of the crankshaft position sensor. 

Inside this crankshaft, there are trigger wheels. These wheels are attached to pulleys on the crankshaft. So, as this crankshaft rotates, the pulley and the trigger wheels also rotate. 

However, you’ll always have one or two teeth missing on the trigger wheel. This creates a significant difference in the magnetic fields.

Moreover, these magnetic changes can only be detected by the crankshaft position because it has a magnet inside it as well. 

This is why it can easily identify the engine’s position, and then it easily relays the engine position to the ECU. Therefore, the ECU can tell when spark plugs can be fired.


What Is the Coil-On-Plug (COP) Ignition System?

Individual ignition coils are placed on top of spark plugs found at the cylinder’s head, which keeps the coils from getting too hot from the exhaust.

This type of ignition is called a Coil On Plug (COP). This makes it simple for the spark plugs to get the voltage.

Moreover, there’s no need for a distributor or a spark plug wire anymore because these ignition systems don’t need them. They also help car owners avoid colossal damage caused by high voltage plug wire malfunction.

Another reason to set up a COP system is that individual coils can start spark plugs when they’re in place.

This means that each cylinder could have its own sparks controlled, which could lead to less pollution and more horsepower due to better control over the timing of the sparks.

Moreover, most cars with a V6 or V8 engine have one ignition coil for each spark plug in a COP system. So, it’s pretty likely for a six-liter engine to have 6 coils inside it.

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Kevin Shaw

Editor-in-Chief at F150Lab

Kevin Shaw has a vast knowledge of pickup trucks, especially the Ford F150. He has been doing various DIY fixes, upgrades, and modifications to pickup trucks for more than five years now.

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