2. Check that the base ignition timing angle matches the nominal value, which for SOHC engines should be 5°±2° before TDC, for DOHC engines 5°±3° before TDC.
3. Stop the engine, turn off the ignition and connect the MUT-II to the diagnostic connector.
Caution! 4. Start the engine and let it run at 2500 min⁻¹ for 2 min.
5. Install the gas analyzer probe (CO and CH) into the exhaust pipe.
6. Measure the CO and CH concentration values at idle speed, which should correspond to the nominal values:
- cO concentration – no more than 0.5%;
- cH concentration – no more than 100 ppm.
7. If the measured values deviate from the nominal values, perform the following checks:
- fault code (output signal of diagnostic system);
- closed-loop control system (in case of normal operation of the closed-loop control system, the output signal of the oxygen sensor varies from 0 to 400 mV and from 600 to 1000 mV at idle);
- injectors;
- ignition coil, high-voltage wires and spark plugs;
- no leaks in the exhaust gas recirculation (EGR) system and EGR valve;
- fuel vapor recovery system;
- compression.
Caution! If the concentration of CO and HC exceeds the nominal values, even if the test results for all the above-mentioned items (elements) are normal, it is necessary to replace the three-way catalytic converter of exhaust gases