Click & Clack: Let car’s computer explain the sea-level problem

• Reprints

Dear Tom and Ray:

I have a 1993 Toyota pickup with a six-cylinder engine. I live at 6,000 feet, and when I’m there, my truck runs fine. But when I go down to sea level, the truck is very hard to start. It cranks but has a hard time turning over; then when it does finally turn, it runs roughly until I get the truck on the road and the rpms are up. Then it runs fine. Right now I’m staying at a friend’s house that is at about 1,000 feet elevation. I can start the truck fine up here, but as soon as I go down to sea level, it becomes very hard to start, whether the engine is hot or cold. The elevation is the only variable. Any ideas? — Celina

TOM: Well, first you have to tell us how long the “check engine” light has been on, Celina. Then we’ll decide how many yards to penalize you for “withholding information.”

RAY: Problems like this rarely occur without the computer setting a check engine code. So if your light is on, you need to have the vehicle scanned for trouble codes. That will usually help pinpoint the source of the problem.

TOM: If the check engine light isn’t on yet, perhaps because you spend limited time at sea level, where the problem occurs, then you may have what’s called a “pending code.” That means the computer has detected a problem but it hasn’t happened with enough regularity to set the check engine light yet.

RAY: But a scan still will tell you if there’s a pending code stored. So next time you’re at sea level, while you’re experiencing this problem, take the truck to someone and have it scanned.

TOM: My first guess would be that you have something like a faulty air-flow meter. But we don’t have to guess. Your car’s engine management computer knows what’s wrong. Ask it.

• • •

What’s the best way to warm up your engine in the morning? Find out by ordering Tom and Ray’s pamphlet “Ten Ways You May Be Ruining Your Car Without Even Knowing It!” Send $4.75 (check or money order payable to Ruin) to Ruin, P.O. Box 536475, Orlando, FL 32853-6475.

• • •

Get more Click & Clack in their book, Ask Click and Clack: Answers from Car Talk. Got a question? Email Click & Clack by visiting the Car Talk website at cartalk.com.

King Features