To carry out the check, a device is required - a compression meter, with a measurement scale of up to 20 kgf / cm2. The main indicator of compression is the pressure value, which should be 11-12 bar (kgf/cm2), while the difference in its values for individual cylinders of one engine must differ by more than 1.5 bar (kgf/cm2). If this value is exceeded, the engine must be overhauled or replaced.
On gasoline engines, a compression gauge is installed in place of the turned out spark plugs.
The check should be carried out with a fully charged battery, on a warm engine in the following order. Start and warm up the engine to operating temperature (80°С). Read information from the fault memory of the DME system CMCS and eliminate the faults. Erase fault memory.
Disconnect the fuel pump relay, start the engine and run until the remaining fuel is used up. This prevents injection of fuel during the test, damage to the converter and distortion of the results of the test itself.
Attention! High voltage ignition system - life-threatening!
Set the automatic transmission selector lever to the position «N» (gearshift lever - to neutral position) and apply the parking brake. Disconnect the AL of the power wires from all ignition coils, unscrew the spark plugs. Crank the engine several times with the starter, which will remove the remaining waste products of combustion from the engine cylinders. Check the condition of the sealing ring (arrow, fig. 3.31.) on fixture «11.0.226». Screw in fixture «11.0.226» by hand into the spark plug socket and connect the compression tester (fixture «11.0.224»).
Press the accelerator pedal and crank the engine with the starter (10-12 turns), until the increase in pressure on the instrument stops. Record the nominal compression pressure in each cylinder. Take measurements in all cylinders and compare the results. Make a decision about the technical condition of the engine.