I cleaned my mass air flow sensor today. I have a 2006 Ford Focus with 127,000 miles, so it is not new, but the car was running relatively O.K. I decided to clean it, simply because I was curious how much the car would improve after cleaning it. There was no significant drivability problem before cleaning.
On my car, the MAF sensor can be reached from bottom of the car. (I replaced the fog light assembly today, so I had to raise the car anyway.) It’s just behind the radiator on the driver’s side. That’s a little strange place to put a MAF sensor. Anyway, since I was working from underneath, I couldn’t get to it easily. I was able to loosen the two screws that hold the MAF sensor to the intake air hose, but I couldn’t get the electrical wires off. I didn’t want to yank it off and risk breaking anything (Second rule of automotive repair: Don’t break anything that ain’t broke), so I just loosened the sensor and sprayed the MAF sensor cleaner on the thing dangling by the wire. The MAF sensor cleaner dries really quickly. It smells a little like carburetor cleaner and brake cleaner, but not so strong. I assume all the automotive cleaning fluids are carcinogenic, so avoid breathing in anything.
When I started the engine, it seems to idle a little smoothly. It was barely noticeable. The car had the tendency to surge slightly (barely noticeable before the cleaning) when it is under a constant load – like climbing a low grade or accelerating moderately for an extended period of time like 5 seconds or more. That surging seems to be gone. Some say the car responds more readily, but I don’t seems to feel that.
Overall, I am satisfied with the improvement (considering how little time it took to do it), and I would recommend others clean the MAF sensor, if the car has high mileage like mine and if you can do it yourself.