Engine Compression Inspection

WARNING: This page is about a different car, the 2008 Honda Pilot, 2007 Honda Pilot, and 2006 Honda Pilot. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: After this inspection, you must reset the powertrain control module (PCM), otherwise the PCM will continue to stop the injectors from functioning. Select PCM reset using the Honda Diagnostic System (HDS) (see HDS CLEAR COMMAND ).

Warm up the engine to normal operating temperature (cooling fan comes on).
Turn the ignition switch OFF.
Connect the HDS to the data link connector (DLC) (see GENERAL TROUBLESHOOTING INFORMATION ).
Turn the ignition switch ON (II), and select PGM-FI, INSPECTION, then ALL INJECTORS OFF function on the HDS.
Turn the ignition switch OFF.
Remove the six ignition coils (see IGNITION COIL REMOVAL/INSTALLATION ).
Remove the six spark plugs.
Attach the compression gauge to a spark plug hole.

Fig 1: Attaching Compression Gauge To Spark Plug Hole
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Open the throttle fully, crank the engine with the starter motor and measure the compression.
Compression Pressure:

Above 930 kPa (9.5 kgf/cm ² , 135 psi)
Measure the compression on the remaining cylinders.
Maximum Variation:

Within 200 kPa (2.0 kgf/cm ² , 28 psi)
If the compression is not within specifications, check the following items, then remeasure the compression.
- Damaged or worn valves and seats
- Damaged cylinder head gaskets
- Damaged or worn piston rings
- Damaged or worn piston and cylinder bore
Select PCM reset (see HDS CLEAR COMMAND ) to cancel the ALL INJECTORS OFF function on the HDS.