INSTALLATION
(1) Positon the pressure sensor in the air cleaner
cover and install the fasteners (Fig. 22).
(2) Connect the electrical connector (Fig. 22).
(3) Connect the negative battery cable.
MANIFOLD AIR FLOW (MAF)
SENSOR
DESCRIPTION
The Mass Air Flow (MAF) Sensor is located in the
air intake port between the air filter and the turbo-
charger (Fig. 23). The MAF sensor uses semiconduc-
tor technology throughout, and is used to calculate
the air mass flowing past it per time unit. This mass
is important for determining the exhaust gas recircu-
lation rate. The MAF sensor sends a corresponding
signal to the ECM, which evaluates the signal to
adjust the exhaust gas recirculation valve.
OPERATION
The ECM uses the mass air flow (MAF) sensor to
measure air density. The temperature resistor located
at the front of the MAF sensor measures the temper-
ature of the inlet air. By varying the voltage, the
electronic circuit regulates the temperature of the
heating resistor in the rear so that it is 320° F
(160°C) higher than the temperature of the intake
air. The temperature at the heating resistor is mea-
sured by a sensor resistor in-between.
Because the incoming air has a cooling effect, the
greater the amount of air that flows in, then the
higher the voltage of the heating resistor. The heat-
ing resistor is therefore a measure of mass of air
flowing past. If a temperature change occurs as a
result of a increase or reduction of air flow, the ECM
corrects the voltage at the heating resistor until the
temperature difference is again achieved. This con-
trol voltage is use by the ECM as a unit measure for
metered air mass.
REMOVAL
(1) Disconnect the negative battery cable.
(2) Detach the air hose at the Manifold Air Flow
(MAF) sensor
(3) Unplug the MAF wiring harness connector.
(4) Remove the screws retaining the MAF sensor
to the air cleaner housing, and remove MAF sen-
sor.
Fig. 22 AIR CLEANER HOUSING
1 - AIR FLOW SENSOR
2 - GASKET
3 - AIR INTAKE HOSE
4 - AIR CLEANER HOUSING
5 - AIR CLEANER ELEMENT
6 - AIR INTAKE PRESSURE SENSOR
7 - AIR CLEANER HOUSING COVER
Fig. 23 MASS AIR FLOW (MAF) SENSOR
14 - 44
FUEL INJECTION
VA