In this tutorial I'm gonna' explain how to do a cylinder balance test.
This test comes in handy when the engine in your vehicle is suffering a misfire but you're not getting a misfire trouble code to pin-point the dead cylinder.
The cylinder balance test is a very easy test to do on the 2.4L Chevrolet Cobalt, Chevrolet Malibu, Pontiac G5, Pontiac G6, Pontiac Solstice.
Contents of this tutorial at a glance:
NOTE: This tutorial applies to the following 2.4L equipped GM vehicles:
- Chevrolet Cobalt 2.4L: 2006, 2007, 2008
- Chevrolet HHR 2.4L: 2006, 2007, 2008, 2009
- Chevrolet Malibu 2.4L: 2008, 2009, 2010, 2011, 2012
- Pontiac G5 2.4L: 2006, 2007, 2008
- Pontiac G5 GT 2.4L: 2007, 2008
- Pontiac G6 2.4L: 2006, 2007, 2008, 2009
- Pontiac Soltice 2.4L: 2006, 2007, 2008, 2009
What Does A Manual Cylinder Balance Test Do?
In a nutshell a cylinder balance test will help you to find out which cylinder is dead on a misfiring engine.
In most cases, a engine cylinder misfire will light up the check engine with a specific misfire trouble code (P0301, P0302, P0303, P0304).
This specific misfire code tells you which engine cylinder is ‘dead’ and helps in troubleshooting the cause.
In some cases the fuel injection computer does not register a misfire trouble code or registers a P0300 Random Misfire trouble code when the engine is suffering a bona-fide misfire and is idling rough.
This is where a manual cylinder balance test can save the day, since you can very easily find out which cylinder is dead without the help of a specific misfire trouble code.
The Cylinder Balance Test
The cylinder balance test, on the 2.4L Chevrolet Cobalt (Chevrolet Malibu, Pontiac G5, Pontiac G6, Pontiac Solstice) simply involves disconnecting one ignition coil at a time from its electrical connector.
If the cylinder is ‘dead’, then unplugging its electrical connector will have no effect on the engine's idle.
If the cylinder is ‘alive’ (working and producing power), then unplugging its electrical connector will cause the engine's idle to worsen. In other words, you'll definitely see the engine react and will shake more.
NOTE: You'll be working around a running engine, so be careful and take all necessary safety precautions.
These are the test steps:
Start the engine and let it idle.
Disconnect the cylinder #1 ignition coil from it's electrical connector (the photo above will help you identify the engine cylinders).
Unplug the ignition coil just long enough to see how the engine will react and then reconnect it back to its electrical connector.
NOTE: Don't leave the ignition coil unplugged for too long, since this will load the catalytic converter with a lot of fuel.
You'll see one of two results:
1.) The engine's idle got worse (the engine started shaking even more).
2.) The engine's idle did not get affected.
Repeat steps 2-3 on the remaining cylinders.
Let's analyze your test results:
CASE 1: The engine shook more when you unplugged the ignition coil. This lets you know that this particular cylinder is working and contributing to engine power.
CASE 2: Unplugging the ignition coil from its connector had no effect on the engine's idle. This test result lets you know that this particular engine cylinder is dead and causing the misfire or rough idle condition.
Now that you have found the dead cylinder, the next step is to find out what's causing it to misfire. Go to: I Found The Dead Cylinder, What Next?