Receiving ECM signal, DC motor type EGR actuator operates EGR valve directly. ECM performs EGR system feed back control with the information of measured mass air flow. (The role of MAFS in diesel engine is different from gasoline engine. Fuel injection quantity is decided by MAFS signal in gasoline engine.) When EGR gas (contains no oxygen) flowing into combustion chamber increases, the air passing through MAFS (contains oxygen) decreases. Thus, with the output signal change of MAFS accompanied by EGR actuator actuation, ECM determine the amount of recirculated EGR gas uantity.
NOx is produced from the reaction of nitrogen and oxygen. Controlling EGR gas (contains no oxygen) which is recirculated to combustion chamber, if least intake air required for complete combustion flows into combustion chamber, NOx decreases because there is no supplementary oxygen to react with nitrogen.
P0404 is set when EGR actuator is wide opened or close more than 4 sec.
Item | Detecting Condition | Possible Cause | ||
DTC Strategy |
•
Signal monitoring |
•
EGR actuator motor circuit | ||
Enable Conditions |
•
Engine running | |||
Threshold Value |
•
EGR actuator motor temperature is high.
•
EGR actuator motor is stuck with opening or closing | |||
Diagnostic Time |
•
4.4 sec. | |||
Fail Safe | Fuel cut | NO | ||
EGR Off | YES | |||
Fuel Limit | YES | |||
Check Lamp | ON | |||
Fig.1) Approx. 5% duty signal waveform of Electric EGR control valve (with EEGR valve closed)
Fig.2) Approx. 57% duty signal waveform of Electric EGR control valve(with EEGR valve opened)
he output of approx. 5% duty is mainly for the diagnosis of Electric EGR control valve circuit than actuating EEGR.
