Q: I was wondering if you could solve a problem that has baffled myself as well as a half-dozen mechanics. I own a 1997 Buick Century Custom Edition in which the "service engine" light comes on frequently. It may come on at any time — on the highway, low speed, or parked. It also appears during any temperature. I've brought it to a number of mechanics who have run diagnostics and tune-ups and have tried everything and seem to think it may be a computer glitch. The car runs well whether the light is on or off. Any guess as to what it may be?
A: If you have a misfire problem in this engine, I would suggest you explore the antifreeze overflow bottle for low quantity. Also check the air filter area and tube for the presence of antifreeze. This engine is very prone to intake manifold failures. Left unchecked, it could cost you an engine. With the information you are giving me, I would pay very close attention to the intake manifold for air or antifreeze leaks. Just a last thought, has anyone looked at the MAF sensor numbers? I would hate to think a dirty MAF sensor is giving you fits.
Q: I have a 2007 Mustang I bought used in October 2007 with approximately 19,000 miles. When I don't drive the car every day and definitely for two days in a row, I come out and find my battery dead. This has happened four times. The dealer and roadside assistance say that even though the car is turned off and there doesn't appear to be any lights etc. on, the computers, etc. keep working and that drains the battery. Somehow this doesn't sound right. Can you help?
A: This is an easy problem. You have a parasitic draw in the car. What that means is simply that some component is staying activated and drawing the battery down. The accepted milliamp draw on your car should not exceed 85 milliamps. Anything more than that and you will have the problem as you described. An ASE-certified technician who is comfortable with a digital volt ohm meter and can read wiring diagrams can find where the offending component is. A word of warning I have for you would be to look first at any add-on items in the car, such as an upgraded stereo system.
Q: I think a little education on fuses would be good for your readers. So many times I see someone writing in with a problem, and they always want to blame the fuse. I think a lot of people don't understand what fuses are for. If a fuse is blown it is not the problem, it is an indication of a problem elsewhere. Sometimes they will replace a fuse that isn't even blown.
A: Real good point. A fuse is just a protector of an electrical circuit to prevent fires. Its job is simple actually. If there is too much amperage in the circuit, the inline fuse will blow and take power away from the devices it protects. The manufacturer of the vehicle has designated what size fuse is used to protect each circuit. Using a larger fuse is just inviting problems. Fuses do not cause problems, a fuse prevents problems.
Car Care Tip: Try to plan your trips to use your car less and save on the price of fuel.
Larry Rubenstein is a master technician who owns a North Shore service station. His column appears Sunday in WheelsNorth. Write to Larry c/o The Eagle Tribune, 100 Turnpike St., North Andover, MA 01845, or send e-mail to scanauto@aol.com.
