The pressure data obtained during the measurement on each cylinder of a gasoline engine should not differ by more than 3 bar. If the pressure in one or more cylinders differs from the pressure in other cylinders by more than 3 bar, then this indicates a defect in the valves, wear of the piston rings or working surfaces of the cylinders, as well as the cylinder head gasket.
When performing a compression test, the temperature of the engine oil must be at least +30°C. At this oil temperature, the oil filter is quite warm to the touch. Warm up the engine if necessary.
1. Turn off the ignition.
2. Remove the fuse 28 of the fuel pump (see illustration).
9.2. Remove fuse 28 fuel pump
3. Remove engine protection covers (see arrows in illustration).
9.3. Remove engine protection covers (see arrows)
4. Unscrew the bolts (see arrows in illustration) fastening the expansion tank 2 of the coolant and move the tank away from the place of work without disconnecting hoses 1 and 3 from it. The wire of the coolant level sensor must be disconnected.
9.4. Unscrew the bolts (see arrows) fixing the expansion tank 2 of the coolant and move the tank away from the place of work without disconnecting hoses 1 and 3 from it
5. Remove the cap from the power steering reservoir (see arrow in illustration).
9.5. Remove the cap from the power steering reservoir (see arrow)
6. Remove the bolt (see arrow in illustration) fixing the guide tube of the oil dipstick.
9.6. unscrew the bolt (see arrow) fixing the guide tube of the oil dipstick
7. Remove cover 2 of the air filter, and also remove the clips (see arrows in illustration) and remove air duct 1.
9.7. Remove the cover 2 of the air filter, and also remove the clips (see arrows) and remove air duct 1
8. Release the plug 3 of the canister solenoid valve from the holder 2 (see illustration), then remove the valve.
9.8. Release the plug 3 of the canister solenoid valve from the holder 2
9. Disconnect plug 4 of the mass air flow sensor (see illustration 9.8).
10. Disconnect the fresh air pump hose 1 to the exhaust valves (see illustration 9.8).
11. Remove the clamp 5 fastening and disconnect the supply air duct from the air filter housing.
12. Remove the bolt (see arrow in illustration 9.8) fasteners and remove the air filter housing together with the mass air flow sensor.
13. Disconnect the plugs 1-4 from the ignition coils, unscrew the bolts 5 and 6 and move the coil wiring harness away from the place of work (see illustrations 9.13 and 9.13a). Then carefully remove the ignition coils (see arrows in illustrations 9.13 and 9.13a).
9.13. Disconnect the plugs 1-4 from the ignition coils, unscrew the bolts 5 and 6 and move the coil wiring harness away from the place of work. Then carefully remove the ignition coils (see arrows). Left cylinder head | 9.13a. Disconnect the plugs 1-4 from the ignition coils, unscrew the bolts 5 and 6 and move the coil wiring harness away from the place of work. Then carefully remove the ignition coils (see arrows). Right cylinder head |
14. Screw the compression tester into the spark plug socket, following the instructions for use.
15. Ask the assistant to keep the accelerator pedal pressed until the end of the test.
16. Let the engine make about 8 revolutions until the increase in pressure recorded by the compression gauge stops. Read the pressure gauge readings.
17. Install the dismantled components in the reverse order of removal.
Attention! Disconnection of the plugs is registered by the engine control unit as a fault. In this regard, it is recommended that you contact the workshop to delete the recording as soon as possible.
Table of compression values
nominal value | limit value | |
Compression, bar | 10-14 | 9 |
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