Ask the car doctor

May 24, 2013

3 minutes to read

Q. My 1995 Lexus SC400, after sitting for a week and previously running perfectly, feels like it is running on two cylinders. My mechanic checked the catalytic converter and changed the ignition coil. This made a slight difference, but it still isn’t right. The mechanic advises that the problem may be a jumped timing belt, but he is not sure. The dealership advised that if it is a timing belt problem, the engine may have valve damage. Please help.

A. For a car to run properly it needs fuel, spark for ignition, and proper engine compression. I would start with a recheck of the basics. This should include fuel volume and pressure tests, ignition system testing, and engine/valve timing. There are two ignition coils in this model; the second coil could have also failed.

Q. I really like the Jaguar XF; it has great lines and good performance with its V-8 engine. But living here in the Northeast I’m worried about driving a rear-wheel-drive car in the snow. I know you have said in the past that a rear-wheel-drive car with traction/stability control and snow tires can handle winter, but there are no snow days in my line of work. Do you have a suggestion for a great looking all-wheel-drive car?

A. You don’t need to look any further than Jaguar. Starting with the 2013 model, the XF is available in all-wheel-drive. Although you lose the V-8 engine, you do get a fuel efficient six-cylinder supercharged engine that produces 340 horsepower. The older 5.0 liter V-8 engine was producing just over 300 horsepower, so you are not sacrificing any performance. The all-wheel-drive system is completely seamless in its operation and only makes itself known when the roads get slippery. I still continue to think that the Jaguar XF is one of the best luxury car values.

Q. I have been using a gasoline additive, which supposedly is an upper cylinder lubricant and fuel injector cleaner. The product touts that it will improve gas mileage—in fact, it claims the cost of the product will be offset by the fuel economy saving. It is manufactured by a well known name in additives. Can these fuel additives really work?

A. If the car is properly maintained, then the additives are not going to change the fuel economy. If the car needs maintenance, then the additives may help by removing carbon deposits and improving overall drivability, which in turn may improve fuel economy.

Q. I have a 1995 Volvo 960, with 90,000 miles on it. I spend about $3,000 a year on maintenance and am very attached to the car. I have had the since it was almost new. Am I crazy to spend this much on this car?

A. It is always cheaper to maintain an old car than to buy a new one. Although, at some point you may want to trade old faithful for a newer, more dependable vehicle that has the latest safety features, returns better fuel economy, and is kinder to the environment.

Q. My boyfriend owns a 1993 Mazda MX6. This old car is always having one thing or another wrong with it. One day it smelled terribly of rotten eggs. At first I thought nothing of it, figuring it was the catalytic converter. Then we saw smoke under the hood and realized it was the battery causing the trouble. We replaced it, and for about 20 miles it was fine. Then bam, the smell was back, not as strong, but just as nasty. We went back to the garage and they did an alternator test and said the alternator is fine. They replaced the battery again, and cleaned off the battery acid on the connections. Well guess what? The battery went again. I was just wondering if you have any idea why the battery would keep dying.

A. The alternator is overcharging. Your car uses an alternator with a built-in voltage regulator. The problem could be a faulty alternator, voltage regulator, or wiring issue. Some time spent with a volt-meter and a wiring diagram should allow you to find the problem.