My Mazda's accelerator pedal sticks in cold weather.

Dear Car Talk

Dear Car Talk | Mar 01, 1997

Dear Tom and Ray:

My 1991 Mazda 626 now has 128,000 miles on it. When the engine is cold, no
matter what the outside temperature, the accelerator pedal sticks until I
stomp on it -- with a certain amount of force -- after the engine is
running. Once I force it past this sticking point, it behaves normally.
Although once or twice it has stuck slightly while driving -- generally
after coasting or decelerating. Also, once while in a hurry, I put the car
in gear and drove away without first stomping on the pedal, and it lurched
forward as I pushed the pedal past the sticking point. I quickly learned
not to do that again! The independent garage I took it to sprayed the cable
linkage with WD-40, but that didn't fix the problem. Do you know what's
wrong? -- Jacques

TOM: WD-40 won't work, Jacques. I've used WD-40 successfully for many years...

RAY: ... .mostly for personal grooming!

TOM: But this is not a case for WD-40. What's happened is that your
throttle plate -- that thing that opens and closes when you step on the gas
pedal -- has worn a groove in the throttle body that surrounds it. Every
time it closes, it wears away a little bit of the softer aluminum housing,
and now it's made itself a nice little groove where it's getting hung up.

RAY: Here's the cheap solution, Jacques. There's a throttle stop -- a screw
that you can turn to open the throttle slightly -- and you may be able to
set it so that it stops the throttle just above the groove. In other words,
you don't let the throttle plate close all the way.

TOM: That's like having your foot slightly on the gas pedal all the time,
so you have to compensate for the higher idle by turning the air bleed
screw and reducing the air flow. Just be sure that your mechanic does this
while the car is on the emissions machine, because if it's not done
carefully, you won't pass your next emissions test.

RAY: If that trick doesn't work -- if the groove is already too deep --
then you're going to have to replace the whole throttle body. That'll cost
you several hundred dollars, Jacques. Mon Dieu!

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