Never leave your car running

Dear Mike: How short a quick stop is short enough to make it less expensive for me to leave my car’s engine running when I go into a shop? I have a locking club for the steering wheel.

— W.M., via Internet

A: Never leave a vehicle running unattended, locked or not. There’s too much potential for it to slip into gear, or be put into gear by a child, and start moving.

Common wisdom holds that a vehicle uses more gas to restart the engine than to leave it running, but that’s just an old wives’ tale. Vehicles, particularly with modern fuel-injected engines, use virtually no extra fuel to restart. And they use exactly none when they are shut off. They do use fuel when idling. Do the math.

Dear Mike: Are there any legal recharge kits — with a legal R-12 substitute — to top off the air conditioning system on older cars ?

— M.S., via Internet

A: You need to have air-conditioning certification to buy R-12. I don’t recommend any of the substitutes.

If your system is leaking, you really should get a technician to fix the leak instead of just topping off with refrigerant once a year. Adding a can every year or so was OK back when R-12 was $0.99 and we hadn’t heard of global warming, but things have changed since then.

Dear Mike: I have a 2001 Dodge Ram Pickup. My keyless remote has deprogrammed itself. My owner’s manual has instructions to program a remote if you have an extra active one, but I only have the one. The dealer wants $75 to program it, which seems a bit high.

Can you tell me how this is done?

— E.T., via Internet

A: Unfortunately, the dealer is the only place where you can get the code you need.

Dear Mike: I bought a new Ford F-150 4.6-liter, 4x2 Supercab. I think there is a problem with the idling of the engine, but Ford does not agree.

When I start it up, it idles at 1,200 rpm for about a full minute, then tapers off for the next minute, down to 1,000 rpm. I brought this up to the dealer because I do not think it is good practice to put it in gear at a higher rpm. Am I thinking wrong on this?

They told me this is computer controlled and that they cannot (or will not) adjust it. Aren’t computers programmed by humans? I also drive a 2005 F-150 that starts up at 1,200 rpm for about 10 seconds and then drops back to 900 rpm.

A: The higher initial idle is for two things: First, to ensure good oil pressure immediately. And more importantly, at least from the car manufacturer’s viewpoint, is to heat up the catalytic converter ASAP to meet emissions regulations.

It won’t hurt to put your car into gear before the idle comes down. In fact, when cars had carburetors with chokes, the fast-idle cam would keep the idle higher than your 1,200 rpm for longer. The high initial idle is preprogrammed into the computer, and the dealer really has no way to change it.

Dear Mike: After leaving my parking brake on for months, the rear wheels of my 1988 Chevy Beretta won’t engage. I’ve been told that the cable is rusted into the “on” position. What should I do?

— M.S., via Internet

A: It’s probably a combination of the cable rusting and the brake shoes rusting to the drums. Start by getting under the car and loosening up the parking brake cable at the splitter in the center. You might be able to loosen up the shoes by rocking the car back and forth a few times. Otherwise, you’ll have to remove the wheels and beat on the brake drums with a hammer to loosen them up.

You almost certainly should replace the shoes and turn the drums as soon as you can, or have a mechanic do it.