2. Before starting the verification procedure, check:
- engine oil condition and level;
- the condition of the battery and its charge level. The battery must be fully charged.
3. Disconnect the high-voltage wires from the spark plugs (see section "Spark plugs").
4. Remove all spark plugs.
5. Perform the procedures necessary to prevent the engine control module from commanding fuel injection and ignition.
6. Cover the spark plug holes with a clean rag and, after turning the crankshaft with the starter, check that there are no foreign particles on the rag.
Attention:
- Stay clear of the spark plug holes while cranking the engine with the starter.
- If during the measurement of the pressure at the end of the compression stroke in the cylinder (as a result of cracks appearing) if coolant, oil, fuel, etc. gets in, these substances will heat up and fly out of the spark plug hole under pressure, which is a dangerous phenomenon.
7. Install the compression gauge into the spark plug hole.
8. Turn the engine crankshaft with the starter at fully open throttle and measure the pressure at the end of the compression stroke.
The difference between the minimum pressure value in one of the cylinders and the maximum value in one of the cylinders must not exceed 70% of the maximum value.
9. If the end-of-compression pressure in any cylinder is below the minimum permissible value or the difference in end-of-compression pressure between cylinders exceeds the maximum permissible value, then pour a little engine oil into the spark plug hole of that cylinder and repeat the measurements in step "8".
Attention:
- If, after filling with oil, the pressure at the end of the compression stroke has increased, then the cause of the malfunction is wear or damage to the piston ring and/or cylinder bore.
- If after filling with oil the pressure at the end of the compression stroke does not increase, the reasons are burnt or damaged valve seat, or gas (pressure) leakage through the cylinder head gasket.
10. Install the spark plugs.
11. Connect the high-voltage wires to the spark plugs.