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Click & Clack

CLICK & CLACK : Stopping the Unwanted Go

Sunday, April 3, 2005; Page G02

Q Dear Tom and Ray:

Do you know of any sudden-acceleration problems with Subaru vehicles? My 2004 Outback suddenly accelerated, on its own, while my foot was on the brake. I had to stand on the brake to avoid surging into traffic. It continued at super-high revs when placed in park, then subsided on its own. Subaru claims ignorance, even though I found several similar complaints online. I am taking it to the dealership tomorrow but wondered if you have any clues as to what could have caused the problem. -- Jaye

A TOM: This continues to be a controversial issue, Jaye. And Subaru is far from the only manufacturer to hear these sorts of complaints.

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RAY: In our experience, unintended acceleration has a number of causes. The simplest one is someone accidentally stepping on the gas pedal when intending to step on the brake. Or stepping on both pedals at the same time -- and the gas pedal wins.

TOM: Obviously, if you put it in park and take your feet off the pedals, and the engine is still revving high, that's not your problem. But misapplication of the pedals is a real problem -- more so in the winter, when people wear big clodhopper boots that are wide and that make their feet numb to what they're stepping on.

RAY: We've also seen accelerator pedals get stuck under floor mats. So don't overlook the simple stuff.

TOM: Another cause of unintended acceleration is an old-fashioned sticking throttle. In fact, Subaru had a problem on some six-cylinder Legacys (only six-cylinder models) and WRXs a few years ago in which the cruise-control cable would come out of its track and jam the throttle cable. There's a Technical Service Bulletin for this, and it's fixed by adding a retaining clip for the cruise-control cable.

RAY: And then there are the more mysterious causes of "UA." These are the cases in which the computer is suspected. The fact is, every car built these days has computerized engine controls. One of those controls allows the computer to open the car's airway beyond the throttle.

TOM: This allows the computer to adjust the idle speed when, for instance, the air conditioner comes on and draws power from the engine.

RAY: But since it can adjust the idle speed on its own, it -- theoretically -- has the ability to malfunction and cause unintended acceleration. Unfortunately, it's hard to diagnose unless your mechanic can actually catch it in the act.

TOM: And, as we said, this can happen on any modern car, not just Subaru.

RAY: So, if you're absolutely sure that your foot or your floor mat was not the culprit, ask your dealer to keep the car for a few days and get the service manager to drive it home. With a little luck, the problem will happen to him, and he'll be newly motivated to fix it.

TOM: You should also report your problem to the National Highway Traffic Safety Administration. It's at www.nhtsa.gov, or by phone at 888-327-4236.

Got a question about cars? Write to Click & Clack in care of The Post, or visit the Car Talk Web site at www.cartalk.com.

©2005 by Tom and Ray Magliozzi

and Doug Berman

© 2005 The Washington Post Company