CYLINDER DROP TEST

CYLINDER DROP TEST

Fig. 1: These pliers are insulated and help protect the user from shock as well as the plug wires from being damaged

Fig. 2: To perform the cylinder drop test, remove one wire at a time and . . .

Fig. 3: . . . note the idle speed and idle characteristics of the engine. the cylinder(s) with the least drop is the non-contributing cylinder(s)

The cylinder drop test is performed when an engine misfire is evident. This test helps determine which cylinder is not contributing the proper power. The easiest way to perform this test is to remove the plug wires one at a time from the cylinders with the engine running.

Place the transaxle in P, engage the emergency brake, and start the engine and let it idle.
Using a spark plug wire removing tool, preferably the plier type, carefully remove the boot from one of the cylinders.
WARNING
Make sure your body is free from touching any part of the car which is metal. The secondary voltage in the ignition system is high and although it cannot kill you, it will shock you and it does hurt.
The engine will sputter, run worse, and possibly nearly stall. If this happens reinstall the plug wire and move to the next cylinder. If the engine runs no differently, or the difference is minimal, shut the engine off and inspect the spark plug wire, spark plug, and if necessary, perform component diagnostics as covered in this section. Perform the test on all cylinders to verify the which cylinders are suspect.