Paul Brand: Can headlights brighten chance for start in cold?

Q I have heard or read that turning on the ignition or lights for a short time before attempting to start a very cold car will make it easier to start. Is there any truth to this? If so, please explain why and say what procedure you recommend for starting.

A Fact or urban legend? In this case, it's fact. In extremely cold conditions, turning the headlights on for about 10 seconds before trying to start your vehicle can help the battery deliver a bit more cranking amperage, which in turn will increase the cranking speed of the engine, which improves the chances of the engine starting.

Why? That 10-second current draw to operate the headlights can actually warm the electrolyte in the battery a bit, helping it deliver a bit more cranking amperage -- maybe just enough to make the difference between the engine starting -- or flooding.

Q I'm having a problem that's driving me nuts. I have a 2000 Buick LeSabre with the 3800 engine. Normally it starts great, runs well and gets 30 miles per gallon on the highway.

The problem is that I cannot start it when the temp hits about 5-below! It acts like it wants to start, then it floods. I go to flood-clearance mode, it clears out, trying to start in the process. When it clears, it quits trying to start. Stop everything and start over.

Any ideas? I have tried different brands of gas, had Bosch Platinum plugs put in and had the intake manifold replaced. I suspect the crank sensor or maybe the cam sensor. No codes have been displayed. This is the third time this has happened. Your thoughts would be appreciated.

A I don't think this is an issue related to the cam or crank sensors. No fault codes indicate that the computer is receiving information, but it doesn't confirm the accuracy of that information. I'd focus on the coolant sensor. If it is inaccurate at the extremes, it may be telling the computer that it's much colder than it really is. The computer only knows the information it is provided, and in this case it would deliver too much fuel at startup. A scan tool or digital voltmeter would identify the accuracy of the coolant sensor signal.

As a do-it-yourself test, on a subzero morning you could unplug the coolant sensor and try to start the engine. If the engine starts better with the computer using a default value for the missing coolant sensor signal, the coolant sensor is highly suspect. Obviously, this test will cause the "check engine" light to illuminate and store a coolant sensor fault code in the computer.

GM also issued a recall, 03054B, for a faulty fuel pressure regulator on some of these engines. A leaky regulator could lead to a slightly flooded cold-start condition, similar to what you described. A fuel pressure leak-down test would identify a faulty regulator.

Q I helped my daughter buy a 2005 Kia Optima in June 2006. The six-cylinder car now has 44,000 miles. The car runs well, and she has it serviced regularly.

Everything is OK ... except for one thing: When she fills the gas tank, the engine is really difficult to start. I thought that might be because she fills the tank as full as possible, but my wife has driven the car, and she does not overfill.

The starter has to be engaged several times, and when it does finally start, the engine must be revved to keep the rpms up. When you put it into drive, it kind of chugs along and sometimes will die and then be difficult to start again. After the car has been driven for a while, it will start again easily.

This starting difficulty always occurs after filling, and the outside temperature does not make any difference. Once you fill it, the car is very hard to start. After the gasoline level lowers, the car starts very easily. What should my daughter do differently?

A I don't think your daughter's doing anything wrong. I suspect there's a problem with the evaporative emissions system, and I found a service bulletin in my Alldata automotive database addressing this issue. It's bulletin number KT2006032601 dated March 2006. It identifies the possibility of a faulty canister close valve that regulates the induction of fuel vapors from the charcoal canister into the induction system. A problem with this valve could cause precisely the symptom you've described.

Have your daughter contact the Kia dealer. This may -- and I emphasize may -- be covered under the carmaker's warranty or the federal emissions warranty.