COMPONENT LOCATION |
GENERAL DESCRIPTION |
The Mass Air Flow Sensor (MAFS) is located between the air cleaner assembly and the throttle body. The MAFS uses a hot film type sensing element to measure the mass of intake air entering the engine. This hot film type air flow sensor consists of a hot film sensor, housing and metering ducts. Mass air flow rate is measured by detection of heat transfer from a hot film probe. The change in air flow rate causes change in the amount of heat being transferred from the hot film probe surface to the air. A large amount of intake air represents acceleration or high load conditions while a small amount of intake air represents deceleration or idle. The mass of intake air should increase at acceleration and be stable during constant engine speed. The ECM uses this information to determine the injection duration and ignition timing for the desired air/fuel ratio.
DTC DESCRIPTION |
If ECM detects that frequency signal of MAFS is lower than1000 Hz for more than 75 second during one dignostic test(125 second) while enable condition is me,t ECM determines that a fault exists and a DTC is stored.
MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 2 driving cycle.
DTC DETECTING CONDITION |
Item | Detecting Condition | Possible cause | |||||
DTC Strategy | ● Compares the airmeter input frequency to a low limit | ● Poor Connection ● Open or short in harness ● MAFS ● ECM | |||||
Enable Conditions | ● Engine Speed ≥ 500 rpm ● Engine Running Time ≥ 5 second ● Ignition Voltage ≥ 11V | ||||||
Threshold value | ● MAF frequency signal < 1000Hz | ||||||
Diagnosis Time | ● Continuous (More than 75 second failure for every 125 second tests ) | ||||||
MIL On Condition | ● 2 Driving Cycles |
SPECIFICATION |
Air Flow (kg/h) | Frequency (Hz) | Air Flow (kg/h) | Frequency (Hz) | Air Flow (kg/h) | Frequency (Hz) |
0 kg/h | 720 ~ 880Hz | 43.2 kg/h | 3,975Hz | 270.0 kg/h | 7,219Hz |
12.6 kg/h | 2,595Hz | 57.6 kg/h | 4,361Hz | 360.0 kg/h | 7,945Hz |
18.0 kg/h | 2,930Hz | 72.0 kg/h | 4,683Hz | 486.0 kg/h | 8,736Hz |
23.4 kg/h | 3,208Hz | 108.0 kg/h | 5,362Hz | 666.0 kg/h | 9,660Hz |
32.4 kg/h | 3,609Hz | 198.0 kg/h | 6,527Hz | 900.0 kg/h | 10,613Hz |
SCHEMATIC DIAGRAM |
TERMINAL AND CONNECTOR INSPECTION |
1. | Many malfunctions in the electrical system are caused by poor harness and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage. |
2. | Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. |
3. | Has a problem been found? YES ▶ Repair as necessary NO ▶ Go to ” Power Circuit Inspection ” procedure. |
POWER SUPPLY CIRCUIT INSPECTION |
1. | IG “OFF” and Disconnect MAFS connector. |
2. | IG “ON” & ENG “OFF” |
3. | Measure voltage between terminal 2 of MAFS harness connector and chassis ground
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4. | Is the measured voltage within specification ? YES ▶ Go to “Signal Circuit Inspection” Procedure. NO ▶ Check fuse between MAFS and main relay is open or not installed. ▶ Repair open in power harness between MAFS and main relay. |
SIGNAL CIRCUIT INSPECTION |
1. | Check voltage
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2. | Check short to battery in harness
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3. | Check short to ground in harness
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4. | Check open in harness
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GROUND CIRCUIT INSPECTION |
1. | IG “OFF” and disconnect MAFS connector. |
2. | Measure voltage between terminal 1 of MAFS harness connector and chassis ground. |
3. | Measure voltage between terminal 1 and 3 of MAFS harness connector.
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4. | Is the measured voltage within specification ? YES ▶ Go to “Component Inspection” procedure. NO ▶ Repair contact resistance or open in harness. |