Possible Causes
Faulty fuel pump
Faulty fuel injector
Faulty fuel pressure regulator
Faulty fuel line
Faulty fuel supply system
MAF sensor range/performance problem
Manifold absolute pressure (MAP) sensor range/performance problem
Faulty A/F Sensor (Sensor 1)
Faulty Secondary HO2S (Sensor 2)
الأسباب المحتملة
Possible Symptoms
Engine Light ON (or Service Engine Soon Warning Light)
الأعراض المحتملة
Description
The Powertrain Control Module (PCM) detects the oxygen content in the exhaust gas from the air/fuel ratio (A/F) sensor (sensor 1) signal voltage, and it uses fuel feedback control to maintain the optimal air/fuel ratio. The air/fuel ratio coefficient for correcting the amount of injected fuel is the short-term fuel trim. The PCM varies short-term fuel trim continuously to keep the air/fuel ratio close to the stoichiometric ratio for all driving conditions. In case the breather pipe is disconnected, the air amount at the mass airflow (MAF) sensor decreases, and the basic fuel amount decrease; as a result, the fuel injection quantity correction coefficient becomes larger to compensate for the gap. This condition could be seen prominently at low load which the intake air amount is small. The detection of breather pipe disconnection is done by monitoring the gap which is determined by fuel injection quantity correction coefficient average during idle and continuously updating fuel injection quantity correction coefficient. If the fuel injection quantity correction coefficient exceeds a threshold value, the PCM detects a malfunction and stores a Diagnostic Trouble Code (DTC). The purge is stopped by the fuel injection quantity correction coefficient to exclude the influence of purging during the detection.
