How To Test The Coil-On-Plug Ignition Coils (1998-2011 4.6L Crown Victoria, Grand Marquis)

Testing the Coil-On-Plug (COP) ignition coils on the 4.6L Crown Vic or Mercury Grand Marquis is a straightforward and uncomplicated process.

Another good thing about testing them is that you won't need any expensive diagnostic tools. I'll explain how you can test them with a spark tester and a 12-volt automotive test light. I'll also show you where you can buy them.

APPLIES TO: This tutorial applies to the following vehicles:

• 4.6L Ford Crown Victoria: 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011.
• 4.6L Mercury Grand Marquis: 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011.

E-Series Vans: You can find the COP ignition coil tests for the E-Series vans here:

• How To Test The Ignition Coils (2000-2009 4.6L, 5.4L V8 Ford E150, E250, E350).

F-Series Pickups: You can find the COP ignition coil tests for the 4.6L/5.4L V8 F-Series pickups here:

• How To Test The Coil-On-Plug Ignition Coils (1997-2010 4.6L, 5.4L Ford F150, F250, F350) (at: easyautodiagnostics.com).

Symptoms Of A Bad Ignition Coil

As you're already aware, your Crown Vic (Grand Marquis) comes equipped with 8 COP ignition coils. If one of these coils kicks the bucket, you're gonna notice one or more of the following engine performance problems:

• Stumbling and Hesitation: The engine will seem like it's struggling to keep up, especially when you accelerate or go uphill. It feels as if not all cylinders are firing properly.
• Check Engine Light: The check engine light will come on, flashing during the misfire to catch your attention.
• Engine Misfires: You'll experience the engine misfiring, whether you're idling at a stop light or putting the pedal to the metal. The computer's memory will have one or more diagnostic trouble codes (DTCs) related to this problem:
  • P0300: Random Cylinder Misfire.
  • P0301: Cylinder 1 Misfire.
  • P0302: Cylinder 2 Misfire.
  • P0303: Cylinder 3 Misfire.
  • P0304: Cylinder 4 Misfire.
  • P0305: Cylinder 5 Misfire.
  • P0306: Cylinder 6 Misfire.
  • P0307: Cylinder 7 Misfire.
  • P0308: Cylinder 8 Misfire.
• Rough Idle: If your engine's smooth sound/feel turns into a rough, it might be a sign something's off with one (or more) of those COP coils.
• Bad Gas Mileage: One or more faulty ignition coils can lead to your engine guzzling more fuel but not delivering the power.

What Tools Do I Need?

Here's a basic list of the tools you'll need:

• A Spark Tester: The spark tester I recommend for how easy it is to use and its accurate test results is the OTC 6589 Electronic Spark Tester. You can see what it look likes and buy it here: OTC 6589 Electronic Ignition Spark Tester (at: amazon.com).
• Battery Jump Start Cables: You'll use a battery jump start cable to Ground your spark tester to the battery negative (-) terminal (to ensure a good Ground connection).
• 12 Volt automotive test light: The test light will help you check the ignition coil's activation signal.
• Terminal Test Probes Kit: This kit will help you avoid damaging the female terminal of the ignition coil connector when confirming the presence of 12 Volts and the ignition coil's activation signal. You can see an example of this tool and can buy it here: 68 PCS Automotive Circuit Test Lead Kit (at: amazon.com).

Lastly, you'll need a helper to crank the engine for you.

Where To Buy The Ignition Coils And Save

The following ignition coil recommendations are of known automotive brands that I would use/buy myself:

NOTE: Not sure if the ignition coil fits your specific Ford Crown Vic or Mercury Grand Marquis? Don't worry. Once you get to the site, they'll ask you for the specifics of your vehicle. If it doesn't fit, they'll find you the right one.

Making Sure The Connector Locking Tab Is Not Broken

Before you start testing the ignition coils, make sure all eight ignition coil connectors are OK (as in not broken or damaged in any way) and securely attached to their respective coils.

Why check the connectors? Broken locking tabs on these connectors are a super common problem with Ford COP ignition coils.

Here's a bit more detail: Each connector has a plastic tab that locks it to the ignition coil, ensuring it stays in place. Unfortunately, these tabs are notorious for breaking easily, often just from disconnecting the connector.

Since this issue is so common, it's often the cause of misfire problems in Ford COP ignition systems. You can check for this by gently pulling on each ignition coil connector (without pressing the locking tab) to see if it comes off.

If one does come loose, you've likely found the cause of your misfire issue. To fix it, you'll need to replace the connector.You can find new connectors here: PICO 5713PT FORD Ignition Coil-2.

TEST 1: Checking The Ignition Coil For Spark

Testing the ignition coils for spark is quite simple. To get the most accurate test result, it's super important that you use a spark tester.

You can use any spark tester you prefer. I use the OTC 6589 Spark Tester because it's straightforward—just plug it in, crank the engine, and there's no need to interpret spark color or make adjustments.

With the OTC HEI Spark Tester, if it sparks, the ignition coil is good. If it doesn't spark, then the ignition coil has a problem.

The instructions below assume you're testing all eight ignition coils, but you don't have to. Depending on your situation or your diagnostic strategy, you can apply these instructions to testing just one or two ignition coils.

Let's get this pot of water boiling:

1. 1

   Remove the ignition coil from its place on the engine.
   
   NOTE: It may be necessary to unplug the ignition coil from its 2-wire connector to remove it. If so, be sure and reconnect it to continue on to step 2.

2. 2

   Attach a spark tester to the ignition coil (as shown in the photo above).

3. 3

   Ground the HEI spark tester directly on the battery negative (-) post with a battery jump start cable.

4. 4

   Have your helper crank the engine while you observe the spark tester.

5. 5

   You're gonna' get one of two results: Spark or no spark.

6. 6

   Disconnect the spark tester and put the ignition coil back in place.

7. 7

   Repeat the test for all of the remaining ignition coils.

Let's interpret your test result:

CASE 1: All eight ignition coils sparked. This is the correct and expected test result.

If the engine isn't starting or is suffering a misfire issue, it's not due to an issue with the ignition coils.

I recommend taking a look at the following section: Other Common Causes Of A Misfire.

CASE 2: One or more ignition coils DID NOT spark. This generally tells you that the ignition coil that did not spark is bad.

To make sure, we need to make sure it's getting 12 Volts. For this test go to: TEST 2: Making Sure The Ignition Coil Is Getting 12 Volts.

CASE 3: You got NO spark from ALL eight ignition coils.