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HOMESERVICE MANUALSMAZDA2008CX-7 TOURING, 2.3 3, AWDREPAIR AND DIAGNOSISENGINE MECHANICALMECHANICALENGINE MECHANICAL [SERVICE INFORMATION 2.3L)COMPRESSION INSPECTION [L3 WITH TC]
2008 Mazda CX-7 Touring, 2.3 3, AWD

Compression Inspection [L3 With TC]

2008 Mazda CX-7 Touring, 2.3 3, AWDSECTION Compression Inspection [L3 With TC]
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 death, serious injury, or damage. Always keep sparks and flames away from fuel.
  1. Verify that the battery is completely charged. (See BATTERY INSPECTION[L3 WITH TC] ).
  2. Warm up the engine.
    WARNING:
    • Fuel line spills and leakage from the pressurized fuel system are dangerous. Fuel can easily ignite and cause serious injury or death and damage. Fuel can also irritate skin and eyes. To prevent this, always perform the Fuel Line Safety Procedure. (See BEFORE REPAIR PROCEDURE[L3 WITH TC] ).
  3. Remove the charge air cooler.
  4. Remove the ignition coils. (See IGNITION COIL REMOVAL/INSTALLATION[L3 WITH TC] ).
  5. Remove all the spark plugs. (See SPARK PLUG REMOVAL/INSTALLATION[L3 WITH TC] )
  6. Remove the fuel pump relay. (See BEFORE REPAIR PROCEDURE[L3 WITH TC] ).
  7. Remove the fuel injector relay.
  8. Measure the compression pressure using the following procedure.
    1. Press the compression gauge into the spark plug hole.
    2. Fully open the throttle valve.
    3. Crank the engine and measure the compression pressure.

      Compression 

      Standard: 1,280 kPa {13.1 kgf/cm 2  ,185.65 psi} [250rpm] 

      Minimum: 896 kPa {9.14 kgf/cm 2  ,129.96 psi} [250rpm] 

      Maximum difference between cylinders: 196.1 kPa {2.0 kgf/cm 2  , 28.5 psi} 

      Fig 1: Measuring Compression Pressure
      G04859471Courtesy of MAZDA MOTORS CORP.
    4. Perform Steps  1 to  3 for all cylinders.
    5. If it is less than the minimum specification, or there is a cylinder with a compression value that differs from that of other cylinders by 196.1 kPa or more {2.0 kgf/cm 2  , 28.5 psi}  , add a small quantity of engine oil through the spark plug hole and perform Steps  1 to  3.
      • If the pressure increases by adding the engine oil, the piston ring or the cylinder surface is worn, or they are damaged. Perform overhaul servicing.
      • If the pressure does not increase, valve seizure, valve attachment failure, or pressure leakage from the cylinder head gasket might be occurring. Perform overhaul servicing.
  9. Install the fuel injector relay.
  10. Install the fuel pump relay. (See BEFORE REPAIR PROCEDURE[L3 WITH TC] ).
  11. Install the spark plugs. (See SPARK PLUG REMOVAL/INSTALLATION[L3 WITH TC] )
  12. Install the ignition coils. (See IGNITION COIL REMOVAL/INSTALLATION[L3 WITH TC] ).
  13. Install the charge air cooler.
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.