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Home >> Mazda >> 2021 >> CX-30 Turbo >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 17 (Engine Mechanical System (VIN M)) >> Compression Inspection

Compression Inspection

WARNING: This page is about a different variant/trim than selected.
WARNING:
  • Hot engines and oil 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.
  • Highly pressurized fuel may spray out if the fuel line is cut. Due to the following dangers occurring with a fuel spray, always complete the "FUEL LINE SAFETY PROCEDURE " to prevent the fuel from spraying.
    • Fuel may cause irritation if it comes in contact with skin and eyes.
    • If fuel ignites and causes a fire, it may lead to serious injury or death, and damage to property and facilities.
  1. Verify that the battery is fully charged. (See BATTERY INSPECTION [(US)] .)
  2. Connect the M-MDS to the DLC-2.
  3. Warm up the engine to the normal operating temperature.
  4. Display the following PIDs using the M-MDS data monitor function. (See PCM INSPECTION .)
    • RPM (engine speed)
  5. Perform the "Fuel Line Safety Procedure" to remove the fuel pump relay. (See BEFORE SERVICE PRECAUTION .)
  6. Remove the following parts.
    1. Plug hole plate. (See PLUG HOLE PLATE REMOVAL/INSTALLATION .)
    2. Ignition coil/ion sensors. (See IGNITION COIL/ION SENSOR REMOVAL/INSTALLATION .)
    3. Spark plugs. (See SPARK PLUG REMOVAL/INSTALLATION .)
  7. Measure the compression pressure using the following procedure.
    1. Install the compression gauge to the spark plug hole.
    2. Fully depress the accelerator pedal.
    NOTE:
    • The cranking method is as follows.

    MTX 

    • When the ignition switch is pressed with the clutch pedal depressed, cranking starts.
    • When your foot is removed from the clutch pedal during cranking, cranking stops.
    • When the ignition switch is pressed during cranking, cranking stops.

    ATX 

    • When the ignition switch is pressed with the brake pedal depressed, cranking starts.
    • When the ignition switch is pressed during cranking, cranking stops.
    1. Crank the engine and measure the following values simultaneously.
      • Compression pressure
      • Engine speed

      Compression pressure 

      G12188426Courtesy of MAZDA MOTORS CORP.
  8. Remove the compression gauge.
  9. Install the following parts.
    1. Spark plugs. (See SPARK PLUG REMOVAL/INSTALLATION .)
    2. Ignition coil/ion sensors. (See IGNITION COIL/ION SENSOR REMOVAL/INSTALLATION .)
    3. Plug hole plate. (See PLUG HOLE PLATE REMOVAL/INSTALLATION .)
  10. Install the fuel pump relay. (See BEFORE SERVICE PRECAUTION .)
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