Mass Airflow Sensor Operation The Mass Airflow (MAF) sensor directly measures the mass of air being drawn into the engine. The sensor output is used to calculate injector pulse width. The (MAF) sensor is what is referred to as a "hot-wire sensor". The sensor uses a thin platinum wire filament, wound on a ceramic bobbin and coated with glass, that is heated to 200*C (417*F) above the ambient air temperature and subjected to the intake airflow stream. A "cold-wire" is used inside the (MAF) sensor to determine the ambient air temperature. Battery voltage from the EEC power relay, and a reference signal and a ground signal from the PCM are supplies to the (MAF) sensor. The sensor returns a signal proportionate to the current flow required to keep the "hot-wire" at the required temperature. The increased airflow across the "hot-wire" acts as a cooling fan, lowering the resistance and requiring more current to maintain the temperature of the wire. The increased current is measured by the voltage in the circuit, as current increases, voltage increases. As the airflow increases the signal return voltage of a normally operating (MAF) sensor will increase. Testing 1. Using a multimeter, check for voltage by back probing the (MAF) sensor connector. 2. With the key ON, and the engine OFF, verify that there is at least 10.5 volts between the VPWR and GND terminals of the (MAF) sensor connector. If voltage is not within specification, check power and ground circuits and repair as necessary. 3. With the key ON, and the engine ON, verify that there is at least 4.5 volts between the SIG and GND terminals of the (MAF) sensor connector. If voltage is not within specification, check power and ground circuits and repair as necessary. 4. With the key ON, and the engine ON, check voltage between GND and SIG RTN terminals. Voltage should be approximately 0.34-1.96 volts. If voltage is not within specification, the sensor may be faulty. Removal & Installation (4.6L & 5.4L) 1. Disconnect the negative battery cable. 2. Release the air cleaner clamp and separate the air cleaner halves. 3. Remove the grommet from the air cleaner housing and slide the grommet down the hardness. 4. Remove the (MAF) sensor plate and (MAF) sensor from the air cleaner. 5. Detach the (MAF) sensor from the harness. 6. Remove the retaining nuts and remove the (MAF) sensor. 7. Installation is the reverse of removal.
you will almost always have to replace them.
On a 1999 Ford Expedition : The Mass Air Flow sensor is between the engine air filter and the large diameter engine air intake tube ( it is INSIDE a round shaped plastic housing )
On a 1999 Ford Expedition : The Mass Air Flow Sensor is located INSIDE the round shaped plastic housing , between the engine air filter housing and the engine air intake tube
How to locate and clean or replace mass air flow in Mercedes ml320
It does not have a mass air flow sensor.It does not have a mass air flow sensor.
How do i replace mass air flow sensor 1992 lexus es 300
how do I replace a mass air flow sensor on a Hyundai Accent?
It does not have a mass air flow sensor.
A 1999 Chrysler Sebring does not have a mass airflow sensor.
insufficient egr flow
In your air box at the filter side
On a 2001 Ford Expedition , 4.6 : The Mass Air Flow sensor is between the engine air filter and the large diameter engine air intake tube * it is INSIDE the round shaped plastic housing