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.
P0405 is set when feed back EGR valve position out of high limit position for 2.5 secondS. In this case, check that stuck of EEGR actuator, air leakage of intake line.
Item | Detecting Condition | Possible Cause | ||
DTC Strategy |
•
Feed back position monitoring |
•
EGR actuator stuck
•
EGR actuator component
•
Air leakage of intake line | ||
Enable Conditions |
•
Engine "ON" | |||
Threshold Value |
•
feed back EGR valve position out of low limit position | |||
Diagnostic Time |
•
2.5 sec. | |||
Fail Safe | Fuel cut | NO | ||
EGR Off | YES | |||
Fuel Limit | NO | |||
MIL | YES | |||
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)
The output of approx. 5% duty is mainly for the diagnosis of Electric EGR control valve circuit than actuating EEGR.
