1986 Pontiac Fiero th125 on my favorite Fiero having some p

1986 PONTIAC FIERO
111,000 MILES • 4 CYL • 2WD • AUTOMATIC
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CURLRUP
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Out of the blue instead of shifting at 2200 rpms it now shifts at 3200 rpms. When slowing down it shifts really hard out of 3rd gear. It almost jerks the whole car. I unplugged the TC soleniod to see if that was sticking,no change. I changed the fluid and filter yesterday, no change. The old fluid was fine, nice red color no smells, no excessive gunk in it. I see no leaks, it does pump the fluid the length of the car (mid engined) to the radiator in the front for cooling, I see no ATF in the coolant. I also adjusted teh Throttle Valve Cable according to spec, no change. Someone mentioned a 3rd gear preasure switch. A $6 part that is easy to change out. What does this switch do, and would that cause the problems I am having? Please help this is my project car, I love it dearly, and I know very little about transmissions.

Curly
Jan 8, 2009 at 10:22 AM
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2CARPRO JACK
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Does that trans have a vacuum modulator on it? If so it may be what is causing the lengthy shift times and harsh downshifts
Jan 8, 2009 at 10:39 AM
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CURLRUP
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I have no idea if it does. I will check my manual.
Jan 8, 2009 at 10:48 AM
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CURLRUP
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No it does not. No vacuum lines going to that trans. It gets all of it's shift points from the throttle vlave cable. Which I readjusted, to no improvement.
Jan 8, 2009 at 11:03 AM
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MMPRINCE4000
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Shifting is controlled by the TV cable. Remove it at the throttlebody. Pull on it, there should be increasing pressure as you pull it, if not, it may have come loose at the trans. Unbolt at trans and make sure it's connected (an "L" shaped bend on cable attaches to loop on trans, just slides in).

If cable is OK, then govenor, pump. The 3rd gear switch is replaceable. Also check the shift cable for correct position.

Replacement parts are available at fierostore.com.
Jan 30, 2009 at 9:07 AM