Diagnostics can reveal:
- contamination or wetting of the candle;
- contamination or change in injector performance;
- malfunctions in the fuel supply system (pressure regulator, fuel pump, etc.);
- electrical connections in ignition and injection systems broken (reliable connection of high-voltage wires to spark plugs).
Diagnostics is carried out by measuring the change in the instantaneous rotation frequency of the engine crankshaft.
A drop in engine torque indicates incomplete combustion of the combustible mixture.
This diagnostic is performed almost constantly during the entire trip. Performing this diagnostic or identifying a malfunction leads to a ban on performing other diagnostics "using the on-board diagnostic system" (catalytic converter and upstream oxygen sensor diagnostics).
Carrying out this diagnostic allows us to identify two types of defects:
- misfires of the mixture, destructive for the catalytic converter. In this case, the injection system malfunction indicator lamp immediately lights up with a flashing light;
- misfires of the mixture, leading to an increase in the toxicity of exhaust gases above the threshold permitted by the on-board diagnostics system. If misfires were registered during three consecutive trips, the fuel injection system malfunction indicator lamp lights up continuously.
Conditions for detecting faults
Before starting diagnostics, check that programming has actually been performed and that all necessary conditions have been met, including the conditions preceding ignition on. Diagnostics are performed as soon as the coolant temperature exceeds -7.5°C in three engine speed ranges from idle to 4500 min⁻¹.
The test for misfires that lead to increased toxicity of exhaust gases can also be performed with the engine idling for 10 minutes and 40 seconds.
Caution! At the end of this test, do not turn off the ignition under any circumstances before reading the result on the diagnostic tool. Turning off the ignition will result in incorrect interpretation of the results.
Confirmation of repair
Misfire diagnostics is performed: "ACTIVE".
Misfires leading to increased toxicity of exhaust gases: "MALFUNCTION NOT DETECTED".
Misfires leading to failure: "NO CATALYTIC CONVERTER FAILURE DETECTED".
If the diagnostic system detects misfires after performing the test, refer to the diagnostic method corresponding to the malfunction.