Engine Compression Inspection

NOTE: After the inspection, you must reset the engine control module (ECM)/the powertrain control module (PCM). Otherwise, the ECM/PCM will continue to stop the fuel injectors from functioning.

Warm up the engine to normal operating temperature (the radiator fan comes on at least twice).
Turn the ignition switch OFF.
Connect the Honda Diagnostic System (HDS) to the data link connector (DLC) (see step 2 on HOW TO USE THE HDS (HONDA DIAGNOSTIC SYSTEM) ).
Turn the ignition switch ON (II).
'07-08 models: Make sure the HDS communicates with the vehicle and the ECM/PCM. If it doesn't communicate, troubleshoot the DLC circuit (see '07-08 MODELS ).
Select PGM-FI, INSPECTION, then ALL INJECTORS OFF on the HDS.
Turn the ignition switch OFF.
Remove the four ignition coils (see IGNITION COIL REMOVAL/INSTALLATION ).
Remove the four spark plugs (see SPARK PLUG INSPECTION ).
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 of the remaining cylinders.
Maximum Variation:

Within 200 kPa (2.0 kgf/cm ² , 29 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
Remove the compression gauge from the spark plug hole.
Install the four spark plugs (see SPARK PLUG INSPECTION ).
Install the four ignition coils (see IGNITION COIL REMOVAL/INSTALLATION ).
Select ECM/PCM reset (see ECM/PCM RESET ) to cancel the ALL INJECTORS OFF on the HDS.
Do the ECM/PCM idle learn procedure (see ECM/PCM IDLE LEARN PROCEDURE ).