In this tutorial, I'll help you diagnose a BAD COP ignition coil on your Dodge 4.7L SUV or Pickup.
In case you've been wondering what the acronym COP stands for: Coil On Plug, and refers to the fact that there's an ignition coil sitting on top of each spark plug.
To help you navigate this article, here are its main points:
Puedes encontrar este tutorial en Español aquí: Cómo Probar las Bobinas de Encendido (4.7L Dodge) (at: autotecnico-online.com).
The most obvious symptom, you'll see when a COP ignition coil goes BAD, is the check engine light shining nice and bright to let you know that there is a problem. You'll see one or several of the following trouble codes:
Besides the check engine light being On, you'll also see one (or several) of the following symptoms of a BAD COP ignition coil:
The most important tool that you're gonna' need is a spark tester. I'm gonna' recommend one that is the most effective (and the most inexpensive) out there: the HEI spark tester.
From personal experience (I work full-time as an automotive tech)... the HEI spark tester is a must have tool. You don't need to interpret the color of the spark or the weakness of it. With the HEI spark tester... if it sparks... the ignition coil is good.
In a nutshell, the COP ignition coil's job is to create and deliver spark to the spark plug at the precise moment in the engine's Combustion Cycle.
This is all accomplished without all of the moving parts required of a conventional (and outdated) Distributor type ignition system. Here's a basic list of things that a COP coil ignition system replaces:
Now, in case you're really curious about how it works... below is a very brief description of how it works:
Now, although the COP coil ignition system on your Dodge 4.7L equipped pickup or SUV is a major step forward over a Distributor based ignition system... you still have things go wrong. The most common of failures is a COP ignition coil going BAD and causing a misfire (which in turn causes the check engine light (CEL) to illuminate).
Each engine cylinder (and thus COP coil) is assigned a specific number.
This number is used to identify the ignition system firing order. Now, our concern is not the ignition system firing order...
... What we want is just to identify the COP coil the misfire code is accusing of Misfiring.
Using the illustration in the image viewer, you can find out which engine cylinder is the one that's misfiring.
The one thing to keep in mind, is that the misfire trouble code is only a guide. It doesn't tell you that a specific part/component is BAD and needs to be replaced.
This is where this tutorial comes in handy... since I'll show you how to test the COP coils and see if one of them is BAD and thus the cause of the misfire code and misfire condition.
“I never made a mistake in my life. I thought I did once, but I was wrong.”
Charles M. Schulz