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.
The PCM compares the airmeter input frequency to low and high limits. When the frequency is outside the allowable limits, the circuit is determined to be failed.
If PCM detects that frequency signal of MAFS is lower than 1000Hz for more than 75 second failure during one dignostic test(125 second) while enable condition is met, PCM 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.
Item | Detecting Condition | Possible cause |
DTC Strategy | ● Compares the airmeter input frequency to a low limit | ● Poor Connection ● Open or short in harness ● MAFS ● PCM |
Enable Conditions | ● Engine Speed ≥ 500 rpm ● Engine Running Time ≥ 5 second ● Ignition Voltage ≥ 11V ● Conditions met delay time ≥ 1 second | |
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 |
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 |
