How To Test The Ignition COP Coils (Toyota 1.8L)

By: Abraham Torres-Arredondo
Created: 04 May 2013
Updated: 14 February 2024
Articl Id: 453

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TEST 3: Swap The ‘No Spark’ COP Coil

Swapping The Ignition Coils -Toyota 1.8L COP Coils.

In this test step, you're gonna' swap the coil that wasn't sparking with the one next to it (or one of the other three that you know is sparking).

Why swap ignition coils? This is to double check that the one that isn't sparking is still NOT gonna' spark in its new location. And that the one that is sparking will continue to spark in its new location.

Confused? I'll explain it again. The idea behind this ignition coil swap is twofold:

We're gonna see if the non-sparking coil will now spark when connected to another electrical connector.
-AND-
See if the other ignition coil (that is sparking) will spark in the non-sparking coil's electrical connector.

Why this extra step? Again, this is just to make sure that the non-sparking ignition coil is getting all the signals it needs to spark.

Alright, this is what you'll need to do:

1
Disconnect and remove the COP ignition coil that did not spark in the previous spark test section.
2
Choose one of the other COP coils that is sparking and remove it from its place.

NOTE: If you need to make sure that this COP ignition coil is sparking, you can test it with your spark tester.
3
Once the good COP coil is removed, connect it to the bad COP coil's electrical connector.

Next, connect the HEI spark tester to this COP coil.

Ground the HEI spark tester with a jump start cable directly on the battery negative (-) terminal.
4
Place the bad COP ignition coil in the location of the good one you just removed and bolt it down.
5
Have your helper crank the engine once everything is set up.

The good COP coil should spark connected to the connector of the dead cylinder.

If the COP coil sparks, then this confirms that all signals are present in the COP coil connector (of the one that wasn't sparking).

Let's take a look at your test results:

CASE 1: The COP ignition coil sparked. This tells you that the COP coil that did not spark in TEST 2 is bad and needs to be replaced.

Here's why: By placing a good and sparking ignition coil in place of the bad one and having spark still come out of the good one, proves that the non-sparking coil:

Is getting power (10 to 12 Volts).
Is getting the PCM's Triggering Signal (known as the IC (Ignition Control) Signal).
Is being fed with Ground.

CASE 2: The COP Ignition Coil DID NOT spark. This lets you know that the COP ignition coil that did not spark is not sparking because one of the four wires of the connector is missing a signal.

The next step for you is to:

Check that the ignition coil is being fed with power (10 to 12 Volts).
That the PCM's is providing Triggering Signal (known as the IC (Ignition Control) Signal).
That the ignition coil is being fed Ground.

Although these specific tests are beyond the scope of this article, you now have eliminated the ignition coil as bad and now have an idea of what direction your diagnostic/troubleshooting needs to go in.

TEST 4: How To Do A Cylinder Balance Test

There are times that the PCM just doesn't set a misfire code even though the engine is misfiring. This is when doing a manual cylinder balance test saves the day!

In a nutshell, a manual cylinder balance test simply involves disconnecting one fuel injector at a time (while the engine is running) to see which one doesn't have an effect on the engine's idle when unplugged.

NOTE: In a Toyota, disconnecting the COP ignition coil's connector will not work. You have to unplug one fuel injector at a time.

Here's what you'll need to do:

1
Start the engine and let it idle.

NOTE: This test is done with the engine running. So be careful, stay alert, and think safety all of the time.
2
Disconnect and reconnect one fuel injector at a time.

What you're looking out for is the fuel injector that DOES NOT make the engine's idle worse (when you unplug it from its connector). If this happens, then this cylinder is the ‘dead’ one.

In a good cylinder (one that's contributing to engine power), when you unplug the fuel injector from its connector, the engine's idle will get worse. It's noticeable!
3
Write down your test results.

Let's take a look at what your cylinder balance test results mean:

CASE 1: Unplugging a fuel injector had NO EFFECT on the engine's idle. This test result confirms that that cylinder is ‘dead’ and causing a misfire.

You can now start from TEST 2: Check The Ignition Coil For Spark and check to see if the COP ignition coil is bad or not.

CASE 2: Unplugging all of the fuel injectors (one at a time) had NO EFFECT on the engine's idle. This tells you that the misfire is affecting all 4 cylinders and more importantly, it tells you that all of the ignition coils and fuel injectors are working as they should.

Since you have a rough idle condition that can not be pinpointed to just one or two cylinders, I suggest you check:

Test engine compression. Check to see if compression between cylinders varies more than 15%.
Vacuum leak from leaking intake manifold gaskets or vacuum hoses.
Failing fuel pump that is not sending enough volume to the fuel injectors.

Although testing the above conditions is beyond the scope of this article, you now know in what direction you need to take your troubleshooting.

Where To Buy The COP Ignition Coils

You can buy the COP ignition coil at your local auto parts store or if you're like me and need to save money on any kind of purchase, you can buy it online.

You can check it out here:

Toyota 1.8L