How To Do A Manual Cylinder Balance Test (2011-2019 1.6L Ford Fiesta)

In this tutorial, I'll show you how to do a manual cylinder balance test on your 1.6L Ford Fiesta.

This test is a life-saver and the most important first step when troubleshooting a hard to diagnose cylinder misfire issue or a bad/clogged fuel injector.

The really cool thing is that you don't need any expensive diagnostic tools to perform the manual cylinder balance test!

APPLIES TO: This tutorial applies to the following vehicles:

• 1.6L Ford Fiesta: 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019.

What Is A Cylinder Balance Test?

A cylinder balance test (and in our case, it's a 'manual' test since we're not using any diagnostic equipment) is a test that helps identify which engine cylinder is 'dead'.

The test is done by disconnecting one fuel injector (from its electrical connector) at a time with the engine running.

When you unplug the fuel injector, and if the cylinder is working correctly, the engine will run and sound rougher. Reconnecting the fuel injector will enable the cylinder and the engine will run normally again.

Now, if the cylinder is 'dead' to begin with, unplugging its fuel injector will have no effect on how the engine runs. In other words, nothing will change in the engine's idle when you disconnect the fuel injector.

The cylinder balance test helps to quickly identify the misfiring ('dead') cylinder when other means can't. For example, when the fuel injection computer only sets a P0300 misfire trouble code and doesn't identify the specific misfiring cylinder.

Although the cylinder balance test doesn't tell you why the cylinder is 'dead', it's the first step in figuring out if it's not getting fuel, compression, or spark.

Manual Cylinder Balance Test

Before you start the test, I recommend that you practice disconnecting the fuel injectors with the engine off.

The fuel injector connectors are made of plastic, so you've got the be careful to avoid breaking/damaging them. If you find a fuel injector with broken locking tabs, it's important that you replace it.

CAUTION: You'll be working around a running engine, so take all necessary safety precautions.

OK, let's get started:

1. 1

   Crank and start the engine.

2. 2

   Disconnect the cylinder #1 fuel injector.

3. 3

   You should hear and feel a drop in engine idle (RPMs).
   
   If the cylinder was 'dead' to begin with for any reason (lack of spark, low compression, etc.), you won't hear/feel a drop in engine idle (RPMs).

4. 4

   Repeat the test on the same cylinder.
   
   You can repeat this test as many times as you need to be completely sure of your test result.

5. 5

   Reconnect the injector and repeat steps 4 to 6 on the remaining injectors.

Let's analyze the result of your cylinder balance test:

CASE 1: Disconnecting the fuel injector caused a drop in the engine RPMs. This tells you that the specific cylinder you tested is fine and is not the cause of the cylinder failure.

More specifically, this result in this particular cylinder lets you know that the fuel injector, spark plug, and spark plug wire are all OK.

CASE 2: Disconnecting the fuel injector did NOT cause a drop in RPMs. This tells you that the specific cylinder you tested is 'dead'.

The cylinder could be failing for various reasons. For example:

• Bad spark plug (broken, extremely worn, with carbon tracks, etc.).
• Bad spark plug wire.
• Bad ignition coil.
• Low engine compression.
• Bad or clogged fuel injector.

The list of possible failures is a bit extensive, but the most important thing you've already achieved is identifying the misfiring cylinder. This narrows down and focuses your efforts on finding the precise cause of the problem.

I've written several tutorials that will help you further troubleshoot the misfiring cylinder, you can find them here: Tutorials To Help You Find The Cause Of Cylinder Misfire.

NOTE: In some cases, the engine idles so rough that a manual cylinder balance test can't single out a misfiring cylinder. If this is the case in your particular situation, you can conclude that the issue is affecting all four cylinders, not just one.

A possible cause behind a rough idle affecting all cylinders equally could be a leak in the intake manifold affecting the air/fuel mixture. Other possible issues:

• Fuel pressure regulator leaking fuel into its vacuum hose/line (if equipped with one on the fuel injector rail).
• Stuck open EGR valve (if applicable).
• Fuel pump supplying insufficient fuel volume/pressure.
• Large vacuum leak.
• Low engine compression in all cylinders.

Tutorials To Help You Find The Cause Of Cylinder Misfire

After completing the manual cylinder balance test and discovering a cylinder that's not functioning correctly, you might be wondering: What do I do now?

The next step is to troubleshoot the cause behind the cylinder misfire. This involves identifying which of the 3 basic things (that the cylinder needs to operate) is missing. These 3 things are: 1.) Spark, 2.) Fuel, 3.) Air (compression).

Here are some more specific details:

1. Things that can cause a lack of spark to the cylinder:
   • Defective ignition coil.
   • Defective spark plug.
   • Defective spark plug wire.
   • Engine oil leaking onto the spark plugs from the valve cover.
2. Things that can cause a lack of fuel to the cylinder:
   • Bad fuel injector.
   • Clogged fuel injector.
   • Fuel injection computer not pulsing (activating) the injector (very rare).
   • An electrical issue in the injector connector wiring.
   • Broken fuel injector connector.
3. Things that can cause a lack of air to the cylinder:
   • Low engine compression.

The list above may make diagnosing the cause of a 'dead' cylinder seem difficult, but with a good diagnostic strategy, you'll be able to find the exact cause of the failure.

Here are my suggestions (and the diagnostic strategy I use):

1. First, test the ignition coil.
   • The ignition system is often the culprit behind most cylinder misfires.
2. Test the fuel injector second.
   • After ruling out the ignition system as the cause of the misfire, the next step is to make sure the fuel injector isn't internally damaged.
   • How To Test The Fuel Injectors (2011-2019 1.6L Ford Fiesta)
3. Test the engine compression third.
   • After ensuring that the ignition system is providing spark and the fuel injector is injecting fuel into the 'dead' cylinder, the next step would be to check the compression of that cylinder.
   • How To Test Engine Compression (2011-2019 1.6L Ford Fiesta)

You can modify the list of tests to adapt it to your particular diagnostic needs (since there really isn't a specific and unique way to diagnose a cylinder misfire).

More 1.6L Ford Fiesta Test Tutorials

If this tutorial was helpful, be sure and take a look at all of the 1.6L Ford Fiesta diagnostic tutorials in this index:

• 1.6L Ford Fiesta Index of Articles.

Here's a sample of the tutorials you'll find there:

• How To Test The MAF Sensor (2011-2013 1.6L Ford Fiesta).
• How To Test Engine Compression (2011-2019 1.6L Ford Fiesta).
• How To Test For A Blown Head Gasket (2011-2019 1.6L Ford Fiesta).
• Fuel Injector Circuit Wiring Diagram (2011-2013 1.6L Ford Fiesta).