Compression Inspection

WARNING: This page is about a different car, the 2002 Mazda 626. However, it is still accessible from the selected car via links, so may be relevant.

Verify that the battery is fully charged. Charge it again if necessary.
Warm up the engine to the normal operating temperature.
Stop the engine and allow it to cool for about 10 min.
Perform FUEL PRESSURE RELEASE . Leave the fuel pump relay removed.
Remove the spark plugs.
Disconnect the ignition coil connector.
Install the SSTs into the No.1 spark plug hole. See Fig 1.
Fully depress the accelerator pedal and crank the engine.
Record the maximum gauge reading.
Inspect each cylinder as indicated above.
- If the compression in one or more cylinders is low, pour a small amount of clean engine oil into the cylinder and check the compression again.
1. If the compression increases, the piston, piston rings, or cylinder wall may be worn out.
2. If the compression stays low, a valve may be stuck or improperly seated.
3. If the compression in adjacent cylinders stays low, the cylinder head gasket may be damaged or the cylinder head is distorted.
  
  Fig 1: Checking Compression
  Courtesy of MAZDA MOTORS CORP.
  
  Fig 2: Compression Specification Chart
  Courtesy of MAZDA MOTORS CORP.
Remove the SST .
Connect the ignition coil connector.
Install the fuel pump relay.
Install the spark plugs.
Tightening Torque

15-22 N.m {1.5-2.3 kgf.m, 11-16 ft.lbf}