Avenger V6-2.5L VIN N (1998)
Compression Check: Testing and Inspection
1. Before inspection, check that the engine oil, starter and battery are normal. Also, set the vehicle to the following condition:
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Engine coolant temperature: 80 - 95°C (176 - 203°F)
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Lights*, electric cooling fan and all accessories: OFF
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Transaxle: P range
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In vehicles for Canada, the headlight, tail light, etc. will remain lit even when the lighting switch is turned OFF but this is no problem.
2. Disconnect the spark plug cables.
3. Remove all spark plugs.
4. Disconnect the MFI relay (ASD relay) connector to prevent a spark.
5. Cover the spark plug hole with a shop towel etc., and after the engine has been cranked, check that no foreign material is adhering to the shop
towel.
Caution
1. Keep away from the spark plug hole when cranking.
2. If compression is measured with water, oil, fuel, etc., that has come from cracks inside the cylinder, these materials will become heated and
will gush out from the spark plug hole, which is dangerous.
6. Set compression gauge to one of the spark plug holes.
7. Start the engine and measure the compression pressure.
Standard value (at engine speed of 250 - 400 r/min):
1,451 kPa (211 psi) <FEDERAL>
1,393 kPa (202 psi) <CALIFORNIA>
Limit (at engine speed of 250 - 400 r/min):
min. 1,109 kPa (192 psi) <FEDERAL>
min. 1,059 kPa (154 psi) <CALIFORNIA>
8. Measure the compression pressure for and check that the pressure differences of the cylinders are below the limit.
Limit: max. 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 7 and 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 MFI relay (ASD relay) connector.
11. Install the spark plug and spark plug cable.
12. Use the scan tool to erase the diagnostic trouble codes.
NOTE: This will erase the diagnostic trouble code resulting from the MFI relay (ASD relay) being disconnected.
