Engine Compression Inspection

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 step 2 under HOW TO USE THE HDS (HONDA DIAGNOSTIC SYSTEM) ).
Turn the ignition switch ON (II).
Make sure the HDS communicates with the vehicle and the PCM. If it doesn't troubleshoot the DLC circuit (see DLC CIRCUIT TROUBLESHOOTING ).
Select PGM-FI, INSPECTION, then ALL INJECTORS OFF on the HDS.
Remove the four ignition coils (see IGNITION COIL REMOVAL/INSTALLATION ).
Remove the four spark plugs.
Attach the compression gauge to the spark plug hole.

Fig 1: Attaching Compression Gauge To Spark Plug Hole
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Open the throttle fully, then 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 gasket
- Damaged or worn piston rings
- Damaged or worn piston and cylinder bore
Install the four spark plugs.
Install the four ignition coils (see IGNITION COIL REMOVAL/INSTALLATION ).
Select the PCM reset (see HDS CLEAR COMMAND ) to cancel the ALL INJECTORS OFF function on the HDS.