Engine Compression Inspection

WARNING: This page is about a different car, the 2006 Acura MDX, 2005 Acura MDX, 2004 Acura MDX, and 2003 Acura MDX. 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 PCM RESET ).

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 in GENERAL TROUBLESHOOTING INFORMATION ).
Turn the ignition switch ON (II), and select PGM-FI, INSPECTION, then ALL INJECTORS OFF function on the HDS
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.
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 specification, 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 PCM RESET ) to cancel ALL INJECTORS OFF function on the HDS.