Q: My 2014 Honda Accord tested "not ready" when I went in for emission testing. I was told to go out and drive around for a week and come back. I did; same result. The dealer said drive 100 miles between 45 and 50 mph. I did the best I could and the car passed the next test. The problem was called "drive cycle." What is it? If it is common enough to have a name, why can't the equipment be set to test those cars?
M.S., Evanston, Ill.
A: Did you get a "check engine" light recently? Did you have a repair made? Did somebody replace the battery? If so, the engine control module's memory needed to be cleared. Although most codes are deleted right after the repair, others wait to clear until certain criteria are met. The onboard diagnostic system, or OBD, continuously monitors the emission controls, but some emission controls will not clear the readiness monitors until the car goes through an OBD drive cycle. Part of that cycle includes driving the car below 55 mph for at least three minutes and then allowing it to slow down below 30 mph without using the brakes. Then you have to speed back up to between 55-60 mph and hold the throttle steady for five minutes before allowing the car to slow down, again without braking. In other words, drive your car the way most people do. The emissions center test equipment cannot do this for you.
Q: Regarding C.Q. from Flourtown, Pa., about vibrating brakes, I completely agree with your diagnosis of warped rotors. However, when I worked at the local Cadillac dealer, around 1996 we started having similar problems with the DeVille series with lower mileage, usually city-driven. What we found was the rear rotors were rusting where the pads rested for a long time. This would usually cause the vibration at higher speeds, but not at lower speeds. Machining the rotors would only correct the problem temporarily. I felt it was a defect in the metal composition. Replacing the rotors was the only sure cure.
R.R., Evergreen Park, Ill.
A: Thanks for checking in. It is not unusual for rotors to rust while a car sits, especially in wet conditions. It's more common near ocean spray. The brakes will usually vibrate until the surface rust is worn off from several brake applications. We were not aware of a metallurgical problem.
Q: Many cars now have very dark tinted driver and passenger side windows, making it hard to see the occupants from the outside, which makes it difficult to tell whether they are seeing me when I am driving or crossing an intersection by foot. I thought it was illegal to be driving around with such windows.
A: Window tint can help keep the interior cooler, reduce damage to upholstery, cut down on UV rays and look cool. Benefits? Yes, but there are drawbacks for both you (as you stated) and law enforcement officers. There is no federal code regarding tint. Each state dictates the amount of tint, and on which windows it is legal. Tint limits range from zero in New Jersey to 70 percent in California.
Bob Weber is a writer, mechanic and Master Auto Technician.