How to Fix Ford Focus SE Stalling Problemsby Lee Sallings
The most common cause of stalling in your Ford Focus SE relates to control of the air entering the engine. The air entering your engine is measured by the MAF (Mass Airflow) sensor and the onboard computer calculates the proper amount of fuel for that volume of air, as well as the position of the Idle Air Control valve for the proper idle speed. These calculations rely on the gap between the throttle body and the throttle blade. When this gap is eliminated by carbon deposits or the MAF sensor becomes contaminated, the computer can no longer control idle speed.
Start the engine and run it until the temperature gauge in the instrument cluster reads in the normal range. Turn the engine off.
Remove the rubber air duct connecting the throttle body and MAF sensor, using a screwdriver or 8-mm socket and ratchet to loosen the large hose clamps. Unplug the vent tube from its rubber grommet in the duct and lay the duct aside.
Clean the throttle body by spraying a liberal amount of the throttle body cleaner into the throttle body around the throttle blade. Allow the cleaner to sit for a few minutes to soften the carbon deposits. Have a helper hold the gas pedal to the floor while you wipe the residue from the throttle body and blade. Repeat this until the throttle is clean.
Turn the ignition key off. Unplug the electrical connector from the MAF sensor attached to the side of the air filter housing. Remove the two small torx-head screws, that attach the sensor to the sensor housing, using a T-10 size torx driver. Carefully slide the sensor out of the housing.
Spray the exposed sensor wires and sensor disc on the end of the sensor that fits inside the housing, using MAF cleaner. Allow it to dry completely before reinstalling the sensor into the housing. Reinstall the rubber duct and tighten the hose clamps securely. Test drive the Focus to verify that it no longer stalls.
- Use the parts cleaner spray sparingly to avoid fouling a spark plug.
- Excessive amounts of liquid cleaner may settle in the intake manifold and damage the engine upon start-up.
- Wear safety glasses and work gloves when working around a running engine to prevent serious injuries.