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> A/T late shift when cold, cold transmission = late shift to fourth gear
post Sep 21, 2007 - 11:01 AM
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silvercelica97

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couldn't find much on automatic transmissions, but i thought i'd give it a go.

I have a 97 Celica ST with an automatic transmission ~150,000 miles on it. When the temp drops below 60 F it hesitates to shift to fourth gear and will rev up over 4000 rpms before it shifts. This only happens before the car warms up, all subsequent shifts are fine. I now warm up the car for a few minutes before driving it, and it solves the problem.

Should I change the transmission fluid? To my knowledge it's never been changed, but I've heard differing opinions on this. Some say to change it and some say it will do more harm then good since it's old/high miles.

What should I do?

I don't know much about cars...just a girl smile.gif

thanks
post Sep 21, 2007 - 2:36 PM
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rjbibeau



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could be the valve body. i'd call a tranny place and get an estimate and have them diagnose it rather than spending money on parts that you don't need. most likely it's the valve body.


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post Sep 21, 2007 - 2:43 PM
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WannabeGT4



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That's just how it's designed. Early shifts and no shift to overdrive until warm.


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post Sep 23, 2007 - 10:26 AM
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Bitter

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QUOTE(WannabeGT4 @ Sep 21, 2007 - 2:43 PM) [snapback]597940[/snapback]

That's just how it's designed. Early shifts and no shift to overdrive until warm.

and also no OD till the engine is warmed. this serves two purposes, one to protect the engine from being revved high till its warm and secondly to protect the trans from hard WOT shifts till its fluid is warm as well.


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post Sep 26, 2007 - 12:16 PM
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silvercelica97

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Thanks guys.

You're totally right. I looked through my owner's manual and there it was...

Guess I only noticed because my commute changed and my car doesn't get a chance to warm up before I'm on the freeway.
post Sep 26, 2007 - 4:07 PM
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Manny



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This is pretty much the same principal that those cheap "chips" work on. They try to trick your engine into thinkiong that the air is a lot colder than it really is which should increase response time and increase the shift points. All they really do is make you waste gas.... but yea... my AT does the same thing...

-M


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post Sep 26, 2007 - 6:09 PM
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FlamingCelica



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My cars the same way, once it gets passed like a quarter inch above cold it shifts and o/d kicks in. Nothin wrong with it. biggrin.gif

Edit, no clue why I posted this, didn't bother to read that you had found it in the manual. lol

~FlamingCelica


This post has been edited by FlamingCelica: Sep 26, 2007 - 6:15 PM


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post Sep 26, 2007 - 6:53 PM
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twitchh17

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shoes
post Sep 26, 2007 - 6:55 PM
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WannabeGT4



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QUOTE(Manny @ Sep 26, 2007 - 4:07 PM) [snapback]599335[/snapback]

This is pretty much the same principal that those cheap "chips" work on. They try to trick your engine into thinkiong that the air is a lot colder than it really is which should increase response time and increase the shift points. All they really do is make you waste gas.... but yea... my AT does the same thing...

-M


Totally different actually. The "chips" are resistors inline or in place of the IAT(intake air temp) sensor. The Shift points are determined by the coolant temp.


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