Cylinder Power Balance Testing – Can Help Uncover Hidden Engine Issues

Cylinder Power Balance Testing - Can Help Uncover Hidden Engine Issues
Cylinder Power Balance Testing - Can Help Uncover Hidden Engine Issues

Performing a cylinder power balance test; can help uncover hidden engine issues, commonly missed with other tests.

Consequently, cylinder power balance testing, can find issues related to; engine misfires, lack of power or just, a poor running engine.

Furthermore, cylinder power balance testing is often used; along with a cylinder compression and cylinder leakage tests, to further pinpoint the problem.

So, cylinder power balance testing, is one of the best and easiest ways; to find the source of a engine misfire.

Engine misfires can be fairly random and if spaced far enough apart; they should not cause any harm. But, a frequent or steady misfire; will cause a sharp rise in, unburned hydrocarbon emissions.  As a result, you could see, a noticeable drop in power and a significant decrease, in fuel economy.

Cylinder power balance testing, involves disabling one cylinder at a time, then recording the (rpm). Consequently, you can perform a cylinder power balance test, several different ways.

So, knowing each of the options, will allow you to choose the easiest one; for the vehicle you are diagnosing:
  • The capabilities of the (PCM).
  • The ease of accessing the required components.
  • Also, the tools you have available for the job.
Use A Scan Tool To Access Stored Diagnostic Trouble Codes
Use A Scan Tool To Access Stored Diagnostic Trouble Codes
For many OBD-II vehicles, you can identify, which cylinders are misfiring; by using a scan tool, to access stored diagnostic trouble codes (DTCs) in the (PCM). You can also access mode 6 data; which will give you information on, how prevalent misfires are, on each cylinder.

In some cases, you can use the scan tool; to command the (PCM) to perform an automatic cylinder power balance test. And, report the results, right on the scan tool. So, on most newer vehicles, using the scan tool is by far; the best method of performing, a cylinder power balance test.

But, if The System Is Not Setup To Perform The Test Automatically; You Will Have To Do It Manually

Manual Cylinder Power Balance Testing
Manual Cylinder Power Balance Testing

Firstly, you will need to decide whether; to disable the ignition or the fuel, to each individual cylinder. If the engine has port fuel injectors that are accessible; disconnecting the electrical connector from each fuel injector one at a time; will shut off the fuel to the cylinder. If the ignition system is disabled for a cylinder; the fuel will still be delivered. But, will not be burned in the cylinder.

As a result, this may cause it to burn, in the catalytic converter; which can cause it to overheat and possibly be damaged. Therefore, shutting down the fuel is preferable, if it is an option.

Cylinder power balance test, has many options. So, if the engine has individual ignition coils (COP) on each spark plug; you can disconnect the primary electrical connector; which will shut off the spark to the spark plug.

(COP) Coil On Plug Ignition Coil
(COP) Coil On Plug Ignition Coil

If the vehicle has coils that share cylinders (waste spark system); then you can place a 1″ (25-mm) section of vacuum hose, between each coil tower and spark plug wire. Then, connect a alligator clip, from a non powered test light, to a good engine ground. Next, touch the tip of the test light, to each length of vacuum hose; to short out each spark plug, one at a time.

However, if the vehicle has a distributor; disconnect one spark plug at a time, from the distributor cap. Furthermore, it’s a good idea to use a test lead; to ground the spark at the distributor cap terminal. In addition, doing this will help prevent the spark from damaging the ignition module; which shuts down the spark, for the cylinder being tested.

How To Perform A, Cylinder Power Balance Test

Visually inspect the engine to determine the best method, to disable the cylinders. For example, this may include, connecting a scan tool; installing vacuum lines on each coil or removing spark plug wires. If necessary, disable the idle control system:

  • Start the engine and allow it to idle. Now you will need to record the idle (rpm).
  • Using the method chosen to disable cylinders; disable the first cylinder and record the (rpm).
  • Reactivate the cylinder and allow the engine to run for approximately 10 seconds to stabilize.
  • Repeat the steps on each of the cylinders and record your readings. Determine any necessary actions.
You Will Need To Record The Idle (RPM)
You Will Need To Record The Idle (RPM)


So, cylinder power balance testing, is quick and easy to perform. And, it identifies, any cylinders that have problems. But, the results of this test alone, do not specify, what the problem is.

That’s why, comparing the test results, will help you learn more about the problem:
  • Compression testing determines the maximum pressure in the cylinder, on the compression stroke of the piston.
  • Cylinder leakage testing measures, how well the cylinder seals.
  • The cylinder power balance test, compares the contribution of each cylinder, towards maintaining a particular speed.

Finally, by comparing the results, of each one of these tests to each other; one can identify what, may or no be the problem.

Thank You !