Your Engine Computer constantly runs tests on the various sensors. To do that it has to compare some to each other. In this case it may be expecting to see a given amount of air flow through the mass air flow sensor based on the position of the throttle position sensor and engine speed. The fault code isn't saying the MAF sensor is defective, just that it doesn't believe the values it's reporting. That would agree with a vacuum leak or leak in the fresh air tube. A vacuum leak will also cause engine speed to increase but under load there will be reduced power. That means you have to press the gas pedal further than normal. That will affect shift timing and harshness. Besides a vacuum leak, the MAF sensor element could be dirty. Bug juice and other dirt insulates it. The sensor works by warming up a heating element, then watching to see how much the air flow cools it. If dirt insulates the sensor, it won't cool enough making it look like less than the actual amount of air is entering the engine. Some sensors, such as on Corvettes, run a very high current through them to burn any dirt off about 20 minutes after the engine is stopped. I don't know if Ford does anything similar, but to be safe, don't spray any cleaner into the sensor for a good hour or two after stopping the engine.
Monday, March 7th, 2011 AT 8:31 PM