A manual cylinder balance test comes in handy when you need to identify a 'dead' cylinder and the fuel injection computer is not setting a misfire trouble code.
It also helps to pinpoint a cylinder that is causing a rough idle condition.
I'm gonna' explain how to do a manual cylinder balance test in this tutorial. With its test results you'll be able to identify the 'dead' cylinders.
Contents of this tutorial at a glance:
Applies To The Following Vehicles
This tutorial applies to the following vehicles (since they all are equipped with the 2.7L V6 engine):
- 2.7L Chrysler 300: 2005.
- 2.7L Chrysler Concorde: 1998, 1999, 2000, 2001, 2002, 2003, 2004.
- 2.7L Chrysler Sebring: 2001, 2002, 2003, 2004, 2005.
- 2.7L Chrysler Sebring Convertible: 2001, 2002, 2003, 2004, 2005.
- 2.7L Dodge Intrepid: 1998, 1999, 2000, 2001, 2002, 2003, 2004.
- 2.7L Dodge Magnum: 2005.
- 2.7L Dodge Stratus: 2001, 2002, 2003, 2004, 2005.
What Does A Manual Cylinder Balance Test Do?
As mentioned in the beginning of this tutorial, a cylinder balance test will help you identify any cylinders that are misfiring ('dead').
In the majority of the cases, when a cylinder is misfiring ('dead') the fuel injection computer will set a specific misfire trouble code that'll let you know which of the 6 cylinders are misfiring.
But in some cases, the engine will misfire or it'll suffer a rough idle condition but the fuel injection computer does not set a specific misfire trouble code.
In these cases a manual cylinder balance will save the day and pinpoint the 'dead' cylinder(s).
The Cylinder Balance Test
The manual cylinder balance test consists of disconnecting an ignition coil (from its electrical connector) one at a time while the engine is running.
Depending on whether the cylinder is 'alive' or 'dead', you're gonna' see one of two test results that'll let you know if the cylinder is OK or not.
To be a bit more specific: If the cylinder is 'alive' to begin with, then disconnecting its ignition coil from its electrical connector will cause the engine to shake more. In other words, the engine's idle will become rougher and you'll be able to see and hear it.
If the cylinder is 'dead' to begin with, then unplugging its ignition coil will have no effect on the engine's idle.
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?