Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSMITSUBISHI2009LANCER L4-2.4L (4B12)REPAIR AND DIAGNOSISENGINE, COOLING AND EXHAUSTENGINECOMPRESSION CHECKTESTING AND INSPECTION
2009 Mitsubishi Lancer L4-2.4L (4B12)
Compression Check: Testing and Inspection
2009 Mitsubishi Lancer L4-2.4L (4B12)SECTION Testing and Inspection
COMPRESSION PRESSURE CHECK
Required Special Tool:
MB991958: Scan Tool (M.U.T.-III Sub Assembly)
^ MB991824: V.C.I.
^ MB991827: M.U.T.-III USB Cable
^ MB991910: M.U.T.-III Main Harness A
1. Before inspection, check that the engine oil, starter and battery are normal. Also, set the vehicle in the following condition:
^ Engine coolant temperature: 80 - 95° C (176 - 203° F)
^ Lights and all accessories: OFF
^ Transaxle: Neutral (P range on vehicles with CVT)
NOTE: On vehicles for Canada, the headlight, taillight, etc. remain lit even when the lighting switch is in "OFF" position but this is no problem for checks.
2. Turn the ignition switch to the "LOCK" (OFF) position.
3. Disconnect the connector of the ignition coil, and then remove all the ignition coils and the spark plugs.
4. Disconnect the all of the injector connectors.
WARNING
Keep your distance from the spark plug hole when cranking. Oil, fuel, etc., may spray out from the spark plug hole and may cause serious injury.
5. Cover the spark plug hole with a shop towel etc., after the engine has been cranked, check that no foreign material is adhering to the shop towel.
6. Set compression gauge to one of the spark plug holes.
7. Crank the engine with the throttle valve fully open and measure the compression pressure.
Standard value (at engine speed of 200 r/min): 1,440 kPa (209 psi)
Limit (at engine speed of 200 r/min): Minimum 1,000 kPa (145 psi)
8. Measure the compression pressure for all the cylinders, and check that the pressure differences of the cylinders are below the limit.
Limit: Maximum 98 kPa (14 psi)
9. If there is a cylinder with compression or a compression difference that is outside the limit, pour a small amount of engine oil through the spark plug hole, and repeat the operations in steps from 6 to 8.
1) If the compression increases after oil is added, the cause of the malfunction is a worn or damaged piston ring and/or cylinder inner surface.
2) If the compression does not rise after oil is added, the cause is a burnt or defective valve seat, or pressure is leaking from the gasket.
10. Connect the all of the injector connector.
11. Install the spark plugs and ignition coils.
12. Use the scan tool MB991958 to erase the diagnosis codes.
NOTE: This will erase the diagnosis code resulting from the injector connectors being disconnected.
Required Special Tool:
MB991958: Scan Tool (M.U.T.-III Sub Assembly)
^ MB991824: V.C.I.
^ MB991827: M.U.T.-III USB Cable
^ MB991910: M.U.T.-III Main Harness A
1. Before inspection, check that the engine oil, starter and battery are normal. Also, set the vehicle in the following condition:
^ Engine coolant temperature: 80 - 95° C (176 - 203° F)
^ Lights and all accessories: OFF
^ Transaxle: Neutral (P range on vehicles with CVT)
NOTE: On vehicles for Canada, the headlight, taillight, etc. remain lit even when the lighting switch is in "OFF" position but this is no problem for checks.
2. Turn the ignition switch to the "LOCK" (OFF) position.
3. Disconnect the connector of the ignition coil, and then remove all the ignition coils and the spark plugs.
4. Disconnect the all of the injector connectors.
WARNING
Keep your distance from the spark plug hole when cranking. Oil, fuel, etc., may spray out from the spark plug hole and may cause serious injury.
5. Cover the spark plug hole with a shop towel etc., after the engine has been cranked, check that no foreign material is adhering to the shop towel.
6. Set compression gauge to one of the spark plug holes.
7. Crank the engine with the throttle valve fully open and measure the compression pressure.
Standard value (at engine speed of 200 r/min): 1,440 kPa (209 psi)
Limit (at engine speed of 200 r/min): Minimum 1,000 kPa (145 psi)
8. Measure the compression pressure for all the cylinders, and check that the pressure differences of the cylinders are below the limit.
Limit: Maximum 98 kPa (14 psi)
9. If there is a cylinder with compression or a compression difference that is outside the limit, pour a small amount of engine oil through the spark plug hole, and repeat the operations in steps from 6 to 8.
1) If the compression increases after oil is added, the cause of the malfunction is a worn or damaged piston ring and/or cylinder inner surface.
2) If the compression does not rise after oil is added, the cause is a burnt or defective valve seat, or pressure is leaking from the gasket.
10. Connect the all of the injector connector.
11. Install the spark plugs and ignition coils.
12. Use the scan tool MB991958 to erase the diagnosis codes.
NOTE: This will erase the diagnosis code resulting from the injector connectors being disconnected.
RENDER: 1.0x
NO RELATED
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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.