Q: What are the different types and locations of mass airflow sensors in Ford Excursion?
A: For gasoline models from 1999 to 2004, the mass airflow sensor is inside the air filter housing. The system has a platinum hot wire, thermistor, and control circuit in a plastic housing. The sensor uses the hot wire to measure the air's molecular mass entering the engine. As the throttle opens and air volume increases, the wire cools. The circuit ensures the wire stays at a preset temperature by controlling the current. The PCM adjusts the current, and the sensor's output voltage changes accordingly. The PCM measures this voltage, converts it to a digital waveform, calculates fuel injector pulse width, and operates the injectors. MAF sensor circuit issues can trigger a diagnostic trouble code. Ensure the ignition key is OFF, disconnect the MAF sensor's electrical connector near the air filter housing, remove the air filter housing, and then remove the MAF sensor assembly from within. Disconnect the sensor connector, take out the bolts from its base, and separate it. For installation, simply follow the removal steps in reverse.For 2005 and later gasoline models, they feature a drop-in style MAF sensor situated in the air inlet duct. Firstly, disconnect the negative battery terminal cable. Then, detach the MAF sensor's electrical connector, remove its mounting screws, and take it out from the air inlet duct. If reinstalling the old MAF sensor, check the rubber sealing ring at its flange. If damaged, either replace the sensor or fashion a new sealing ring, as the ring comes only with a new sensor. Follow the removal steps in reverse to install.For 6.4L diesel engines, they come with a drop-in style MAP Sensor, akin to gasoline engines, and it's affixed to the air intake tube's top. Ensure ignition is off, disconnect the MAF's electrical connector, and remove its securing screws. When reinstalling, ensure the electrical harness retainer is reconnected to the air cleaner assembly.