The Delphi MAF Sensor is an air mass flowmeter, which operates on the principle of hot film anemometry. A heated element is placed within the air stream, and maintained at a constant temperature above the air temperature. The amount of electrical power required to maintain the heated element at the proper temperature is a direct function of the flow rate of the air mass past the element. PCM uses this information to determine the injection duration and ignition timing for the desired air/fuel ratio.
DTC DESCRIPTION
The difference between values coming from the MAF Sensor and those are calculated is analyzed. This difference, or error, is then compared to high and low limit calibration values, which are functions of engine speed. PCM compares the difference between MAFS output and calculated flow rate value while enable condition is met.
If the acutal air flow is higher or lower than calculated value(threshold) for more than 2min. PCM determines that a fault exists and a DTC is stored. MIL(Malfunction Indicator Lamp) turns on when the malfunction lasts till consecutive 2 driving cycle.
DTC DETECTING CONDITION
Item
Detecting Condition
Possible cause
DTC Strategy
●
The MAF Rationality Diagnostic compares the difference between MAF Sensor output and calculated flow rate value to a calibration value
●
Clogged air cleaner
●
MAFS
Enable Conditions
●
Engine Coolant Temperature ≥ 60℃ (Fully Warmed up state)
●
600rpm ＜ Engine Speed ＜ 3000rpm
Threshold value
●
Acutal Air Mass Value is higher or lower than calculated value
Diagnosis Time
●
Continuous (2 min.)
MIL On Condition
●
2 Driving Cycles
SPECIFICATION
Air Flow (kg/h)
Frequency (Hz)
12.6
2617.0
18.0
2958.0
23.4
3241.0
32.4
3653.0
43.2
4024.0
57.6
4399.0
72.0
4704.0
108.0
5329.0
144.0
5897.0
198.0
6553.0
270.0
7240.0
360.0
7957.0
486.0
8738.0
666.0
9644.0
900.0
10590.0
SCHEMATIC DIAGRAM
MONITOR DTC STATUS
1.
Check DTC Status
(1)
Connect scantool to Data Link Connector(DLC).
(2)
IG "ON".
(3)
Select "DTC" button, and then Press "DTC Status" to check DTC's information from the DTCs menu.
(4)
Read "DTC Status" parameter.
(5)
Is parameter displayed "Present fault"?
▶ Go to "Component Inspection" procedure.
▶ Fault is intermittent caused by poor contact in the sensor's and/or PCM's connector or was repaired and PCM memory was not cleared. Thoroughly check connectors for looseness, poor connection, ending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.
COMPONENT INSPECTION
1.
Visual Inspection
(1)
Check that MAFS is damaged, contaminated or deformed.
(2)
Check tha air cleaner is clogged.
(3)
Has a problem been found ?
▶ Repair or replace as necessary and then go to "Verification of Vehicle Repair" procedure.
▶ Go to "Check MAFS" as follows
2.
Check MAFS
(1)
IG "OFF" and install a scantool
(2)
ENG "ON" and monitor "MAFS" data on the service data.
(3)
Monitor signal waveform at signal terminal of MAFS with scantool.
Specification :Signal waveform will be displayed as follows. (Be aware that the signal of MAFS is not voltage display but frequency display.)
(4)
Are both service data and signalwave form dispayed correctly ?
▶ Go to "Verification of Vehicle Repair" procedure.
▶ Substitute with a known - good MAFS and check for proper operation. If the problem is corrected, replace MAFS and go to "Verification of Vehicle Repair" procedure.
VERIFICATION OF VEHICLE REPAIR
After a repair, it is essential to verify that the fault has been corrected.
1.
Connect scantool and select "DTC" button.
2.
Press "DTC Status" button and confirm that "DTC Readiness Flag" indicates "Completed". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions
3.
Read "DTC Status" parameter
4.
Is parameter displayed "History(Not Present) fault"?
▶ System performing to specification at this time. Clear the DTC
