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Home >> Mazda >> 2011 >> RX-8 Sport, 1.3 2 >> Repair and Diagnosis >> Engine Mechanical >> Mechanical >> Engine Mechanical (Service Information) >> Compression Inspection

Compression Inspection

WARNING:
  • Hot engines can cause severe burns. Be careful not to burn yourself during removal/installation of each component.
  • Fuel vapor is hazardous. It can very easily ignite, causing serious injury and damage. Always keep sparks and flames away from fuel.
  1. Remove the engine cover. (See ENGINE COVER REMOVAL/INSTALLATION .)
  2. Verify that the battery is fully charged. (See BATTERY INSPECTION [13B-MSP] .)
  3. Warm up the engine.
  4. Remove the trailing or leading side spark plug of the front and rear rotors. (Refer to SPARK PLUG REMOVAL/INSTALLATION [13B-MSP] in appropriate Ignition System article .)
  5. Disconnect the eccentric shaft position sensor connector. (See ECCENTRIC SHAFT POSITION SENSOR REMOVAL/INSTALLATION .)
    CAUTION:
    • To cut the fuel injection and ignition, make sure the eccentric shaft position sensor connector is disconnected.
  6. Measure the compression pressure using one of the following procedures:
    1. Install the SST (49 F018 9A0C)  to the trailing or leading side plug hole of the rotor housing.
    2. Depress the accelerator pedal fully and crank for 7 s or more. 
    3. Read the compression and engine speed.

      Compression pressure 

      • Standard: 830 kPa {8.5 kg.cm 2  , 120 psi} [250 rpm] 
      • Minimum: 680 kPa {6.9 kg.cm 2  , 98.6 psi} [250 rpm] 
      • Standard difference in chambers: Within 150 kPa {1.5 kg.cm 2  , 21.8 psi} 
      • Standard difference in rotors: Within 100 kPa {1.0 kg.cm 2  , 14.5 psi} 
      Fig 1: Measuring Compression Pressure
      G05984853Courtesy of MAZDA MOTORS CORP.
    4. Perform the same procedure for the other rotor housing.
    5. If the compression is at the minimum or less, or the difference in the chambers and difference in the rotors exceed the specifications, replace or overhaul.
    CAUTION:
    • If the engine speed when measuring compression differs from the standard, adjust according to the graph.
    1. Standard compression pressure
    2. Minimum compression pressure
  7. Install the spark plugs. (Refer to SPARK PLUG REMOVAL/INSTALLATION [13B-MSP] in appropriate Ignition System article .)
  8. Connect the eccentric shaft position sensor connector. (See ECCENTRIC SHAFT POSITION SENSOR REMOVAL/INSTALLATION .)
  9. Install the engine cover. (See ENGINE COVER REMOVAL/INSTALLATION .)
Fig 2: Compression Pressure Graph
G05984854Courtesy of MAZDA MOTORS CORP.
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