Maintenance manual for sunray hfc4da1-2c china-IV diesel engines
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22.
DTC P0100
Mass air flow (MAF) signals measured by air flow meter without correction
are too strong or too weak (Connection is in open circuit or short circuit).
P0101
Mass air flow (MAF) signals measured by air flow meter with correction are
too strong or too weak (Connection is in open circuit or short circuit).
P0102 Mass air flow sensor negative drift
P0103 Mass air flow sensor positive drift
P0104 Mass air flow sensor zero drift
P1100 Air mass flowmeter software correction is excessive.
Fault Description: Mass air flow (MAF) sensor is an air flow meter which is used in measurement of air inflow of
engine. ECU correctly supplies fuel supply with the use of signals from mass air flow sensor for all engine speeds and
loads. In the case of small air inflow of engine, it is indicated there is vehicle deceleration or engine idling. In the case
of large air inflow of engine, it is indicated there is vehicle acceleration or high engine load. Mass air flow (MAF)
sensor possesses circuits as follows:
One ignition 1 voltage circuit
One ground circuit
One signal circuit
ECU applies a voltage to sensor via signal circuit. The sensor uses the voltage to generate a corresponding frequency
for air inflow which gets through the sensor. During idle running, the frequency changes in the range around 2000Hz.
ECU calculates predicted air flow value with input signals from sensors as follows:
Atmosphere pressure in the case of ignition key connection
Intake manifold absolute pressure sensor
Intake air temperature sensor
Engine coolant temperature sensor
Engine speed
ECU compares mass air flow sensor frequency signal with predicted air flow valve and verify signal lag (lack of
change), too low or too high signal level under given operation condition with the comparison. When D-value
between actual mass air flow sensor frequency signal which is detected by ECU and air flow meter calculated value is
not in preconcerted range, DTC occurs.
Diagnosis Hint: Check mass air flow sensor harness and verify whether harness arrangement is too close to
components as follows:
Intake air temperature signal
Power supply
Intake air flow signal
Ground signal
Air flow meter
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