LS - 1st and 2nd Gen (1990-2000) Discussion topics related to the 1990 - 2000 Lexus LS400

vibrating gas pedal when cold..

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Old 11-13-14, 09:29 AM
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Greg5OH
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Default vibrating gas pedal when cold..

This is an odd one. Its below freezing here now, and when i first turn the car on and start driving, the gas pedal has this weird vibrations to it. Hard to describe. but happens when its cold, and only when moving the pedal, not while its in one position. Goes away after abotu 10 minutes...
any ideas?
Old 11-13-14, 09:55 AM
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bgalarpe
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Sounds like a misfire...check engine light on?
Old 11-13-14, 10:01 AM
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Greg5OH
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nonono, nothign liek that at all. the engine is butter smooth, no codes or anything. its this tiny little vibration, imagine your phone vibrating in your pocket, its about half as intense as that. that kind of speed though. i have felt misfires in other cars and this is nothign like that at all
Old 11-13-14, 11:08 AM
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touch the floor next to the pedal and see if it's vibrating?

May be the trans mount just ever so slightly starting to give up, is the only thing i can think of. Make sure the pedal assembly isn't loose or anything like that as well.
Old 11-13-14, 02:02 PM
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timmy0tool
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when the motor is cold it idles high so more vibes felt is normal. it could be more apparent when it's cold since all the metal/plastics are more stiff. it could just be a harmonic vibration at cold idle. rev the motor and see if the vibes go away at different RPMs.
Old 11-13-14, 06:00 PM
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Weird stuff begins to happen as temps go below freezing. You say that it only happens when the pedal is being moved (ie: pressed) so I am wondering if it is the pedal position sensor hanging up slightly and "chattering" in cold temps. Goes away when the cabin begins to warm. Admittedly, a stab in the dark.
Old 11-14-14, 05:42 AM
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Greg5OH
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randal that sounds more like it. Feels like something trying to turn and its sticky in there. Hard to describe but its nto an engien type vibration at all, the frequency is much higher. and the car has a brand new oem trans mount.
I too was thinking its the TPS. So I assume the TPS is in the cabin on the pedal assembly and not near the throttle body?
Old 11-14-14, 06:27 AM
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TPS is still on the throttle body.

There is an accelerator pedal position sensor but I don't believe that's on the interior side of the cable either.
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