Compression check (Mitsubishi Space Star)

1. Before checking, make sure that the engine oil level is normal, the battery is charged and the starter is working properly. Also prepare the car for checking (warm up the engine to operating temperature).

2. Disconnect the high-voltage wires from the spark plugs.

3. Remove all spark plugs.

4. Disconnect the 7-pin connector from the ignition distributor.

Note: Disconnecting the connector from the ignition distributor will disable the ignition system and fuel injection system.

5. When turning the crankshaft with the starter, cover all the spark plug holes with a towel or cloth. After turning the crankshaft with the starter, check for impurities stuck to the towel.

Warnings

When checking compression, do not stand in front of the spark plug holes.

If coolant, oil, fuel, etc. gets into the cylinder during compression testing (due to cracks), these substances will heat up and be ejected under pressure from the spark plug hole, which can be dangerous.

6. Connect the compression tester to the spark plug hole of cylinder No.1 (Fig. 3.11).





7. Open the throttle valve, turn the engine crankshaft with the starter and record the result.

Nominal compression at crankshaft speed 250-400 min¹: 1598 kPa

Minimum permissible compression at crankshaft speed of 250-400 min¹: 1161 kPa

8. Check the compression in the remaining cylinders and record the readings. The pressure in all cylinders should be the same or differ by no more than the permissible value.

Permissible difference in compression in engine cylinders: 100 kPa.

9. If the pressure in any cylinder is too low, pour a teaspoon of clean motor oil into the cylinder through the spark plug hole and repeat the steps in steps 7 and 8.

• (1) If the pressure increases after adding oil, this means that the piston rings and/or cylinder are worn.
• (2) If the pressure does not increase, the cause is worn or burnt valves or a blown head gasket. Low pressure in two adjacent cylinders almost always means that the head gasket between them is blown.

10. Connect the connector to the ignition distributor.

11. Screw in the spark plugs and connect the high-voltage wires.

12. Use the MUT-II tool to clear diagnostic trouble codes.

Note: The fault code resulting from disconnecting the connector from the crankshaft position sensor will be cleared.