Motormouth: Ignition coils play key role in engine performance

Q: Our warranty for our 2010 Kia Rio was up to 75,000 miles. At 79,000 the engine light went on and we had the dealership check the problem. It turned out that three of our coils went bad. Could you please explain how important these coils are and if this particular car brand has problems with it?

E.H., Chicago

A: The coils that failed are the ignition coils. There is one for each cylinder and they create the high voltage needed to make the spark plugs spark. So, yes, they are very important. We are not familiar with any pattern of failures although it seems that Kia and Hyundai coils do not have as long a life as do other manufacturers.

Q: A little over a year ago, we purchased a used 2010 Dodge Nitro Shock. When winter set in we realized that the heat did not come out of the floor vents as strong as it did other vents. No matter what you changed the setting to it would not come out the floor vents very strong. On very cold days your feet can get numb, while your face and head are burning. We replaced an actuator after diagnosing it online. The actuator moves (we tried it before installing it), but it doesn't open the floor vent. The dealer we bought it from wants to put in a new "heater box" to the tune of $1,500. Others say the actuator needs to be calibrated. Your thoughts?

C.F., Lake County, Ill.

A: Door actuators need to be initialized after installation and a scan tool is required to do it. The dealer has the equipment, but so do many independent repair shops. Try this first, as it is much cheaper than replacing the whole HVAC box.

Q: The fuel gauge needle is stuck on full and has not moved in many miles on my 1986 Monte Carlo. The mechanic told me the repairs are a big job and that the float in the tank may be stuck. Can it be fixed?

A: GM had issues with that vintage of autos due to sulfur in gas damaging the sender unit. The fuel tank must be removed to replace the sender and the labor can become expensive. Almost anything can be fixed except, according to comedian Ron White, stupid.

Q: When a vehicle is featured in a newspaper article the description usually includes the make, model, gas mileage, horsepower, features, interior space, length, width, and sometimes the price as tested. Generally the description does not include the vehicle weight. Most car enthusiasts know that a quick reference guide to vehicle performance is the weight to horsepower ratio. Is the vehicle weight purposely excluded by the article author or by the manufacturer to conceal this factor for buyer consideration?

J.K., Glen Ellyn, Ill.

A: We do not think that carmakers are trying to deceive you. It is a matter of how much information is valuable to the greatest number of potential buyers. Besides, the curb weight varies depending on how the vehicle is equipped. Does it have a four-cylinder or six-cylinder engine? Automatic or manual transmission? Is the interior the base or luxury edition? What kind of wheels and tires does it have? Perhaps you can extrapolate the weight of the car based on its gross vehicle weight rating that appears on the driver's door sticker.