COMPONENT LOCATION
GENERAL DESCRIPTION
Mass Air Flow Sensor which is hot film type senses air quantity to engine cylinders.ECM perform feed back control of EGR system using measured intake air quantity information.(this mechanism is different from gasoline engine's which controls fuel injection quantity according to intake air quantity.) Air quantity to engine cylinders(the air contains oxygen) via MAFS decreases when EGR gas (the air does not contain oxygen) flows in combustion chambers by EGR actuator operation. It can be said briefly that recirculated EGR gas quantity is detected through the change of output voltage of MAFS according to EGR actuator operation.
noteNOx is made from the chemical reaction between nitrogen and oxygen. The least intake air needed in complete combustion of fuel flows in combustion chamber as controlling EGR gas(the air does not contain oxygen) which is recirculate to combustion chamber. Through this process, NOx decreases as the oxygen reactable with nitrogen does not exist.
DTC DESCRIPTION
P0101 is set When mass air flow calculated based on intakemanifold pressure and intake air temperature is above 811mg/st for more than 10 sec.(when mass air flow is too excessive). Checking excessive output from MAFS component is needed.
DTC DETECTING CONDITION
Item | Detecting Condition | Possible Cause |
DTC Strategy | Voltage Monitoring
| MAFS component
|
Enable Conditions | Engine running
|
Threshold Value | When mass air flow calculated based on intakemanifold pressure and intake air temperature is above 811mg/st
|
Diagnostic Time | 10sec.
|
Fail Safe | Fuel Cut | NO | |
EGR Off | YES |
Fuel Limit | YES |
MIL | YES |
MONITOR SCANTOOL DATA
Connect scantool to Data Link Cable (DLC)
Warm engine up to normal operating temperature
Turn "OFF" electrical devices and A/C.
Monitor "MAFS " parameter on the scantool.
EGR actuator operates as decelerating after rapid acceleration when idle EGR does not operate, EGR actuator operating duty decreases as time goes by.
This controlling process lasts for about 90 sec. and EGR actuator turns "OFF" (duty 5.0% ) after 90 sec
COMPONENT INSPECTION
Ignition "OFF", Turn Engine "OFF".
Check that MAFS is installed in correctly according to the direction of arrow on MAFS ASS'Y
Check contamination of air cleaner filter.
Ignition "ON", Turn Engine "ON"
Let IDLE RPM last after warming engine up.
Check the leakage of intake system (the leakage of damage of intercooler)
Check that EGR actuator does not operate.
( EGR actuator turns "OFF" after 90 sec's acceleration and disconnect EGR actuator connector if needed. )
Monitor output voltage of MAFS when engine speed lasts at 750±50 RPM.
Is output value within the specification?
? Go to "Verification of Vehicle Repair"
? Replace MAFS ASS'Y and go to "Verification of Vehicle Repair"
VERIFICATION OF VEHICLE REPAIR
After a repair, it is essential to verify that the fault is corrected.
After connecting scantool select "Diagnostic Trouble Codes(DTCs)" mode to and then clear DTC.
Drive the vehicle within DTC Enable conditions in General information.
After selecting "Diagnostic Trouble Codes(DTCs)" mode and check DTC is recorded again.
Are any DTCs recorded ?
? Go to the DTC guide of recorded No. in scantool.
? System operates within specification.
SCHEMATIC DIAGRAM