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I have a 1997 Altima. Sometime back, I had the "check engine" light come on. The code indicated that it was the "mass air flow sensor." It is an expensive part to replace and I decided to delay the replacement. After some days, the "check engine" disappeared. I did not do anything to bring about this change. Again, after some days, the light came back on and the code indicated the same problem: "Mass air flow sensor." The light has again disappeared. I would like to know the importance of this sensor; would my engine suffer damage if I avoid replacing it? I plan to get rid of the car next year. – Ivan in Scarborough
It depends on how much you drive.
The mass airflow sensor is a critical player in determining fuel mileage and exhaust emissions and one of the most important sensors in the vehicle in that respect.
Today's fuel-injected engines depend on the correct air-fuel ratio to ensure the most complete combustion or use of fuel. The mass airflow sensor monitors the amount of air entering an engine through the intake tract and converts that information into a voltage signal that is sent to the engine control module (ECM). The ECM uses that information to determine how much fuel to mix with that air and tells the ignition system when to fire the spark plug in each cylinder.
Not only is the amount of air a determining factor in that process, so is the weight or density of the air, which varies with temperature and humidity.
At today's fuel prices, the amount of fuel saved by a properly functioning mass airflow sensor might be returned with fewer trips to the pump.
Some of the signs of a worn-out or malfunctioning mass airflow sensor include poor idle and hesitation under initial acceleration – signs the engine is not getting the proper amount of fuel – either too little or too much.
Tire wear
The tires on my car have an unusual heel/toe wear pattern that makes for a noisy and bumpy ride down the highway. The wear pattern described as the leading edge of tread is higher than the trailing edge, so that when you run your hand over the tread from front to back, it gets caught on the next piece of tread; if you run your hand in the opposite direction there is no catching. The car is a 2006 Volvo V70 , turbo AWD. It is not the tire as this is my second, different set that has the same pattern. How can this be corrected and will the tires wear normal after or do I need a new set. – Andrew in Ottawa
What you describe is referred to as "cupping" and this is usually a sign of loose, worn or bent suspension components. The cups or scalloped dips in the tread are most commonly associated with worn shocks or struts.
You didn't give the mileage of your Volvo, but I suspect it is sufficient that the shock absorbers are worn.
The easiest way to test this is to push down on a corner of the vehicle repeatedly until you get a rocking motion going. When you stop, the car should come to a complete rest with one vertical motion – up or down. If it keeps going, the shock at that corner needs to be replaced.
A bent suspension component can sometimes cause cupping, but that would likely show in other areas as well.
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