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post #1 of 7 (permalink) Old 02-11-2015, 06:52 PM Thread Starter
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Weird "problem" withdownshift

1996 4.6L with a reman tranny. This happened with the original tranny too, so I gather it is just with this car. When I am slowing down and get to about 32 mph the car downshifts HARD. It's a jolt. Seems like it's the 3-2 downshift. Is this normal? Is there anything I can do to stop it from happening or is it just a quirk that my car has?
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post #2 of 7 (permalink) Old 02-11-2015, 09:19 PM
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Possibly a broken accumulator spring?
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post #3 of 7 (permalink) Old 02-11-2015, 10:33 PM Thread Starter
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I kind of doubt it. It was the same way on the original transmission. Just wondering if anyone has any theories that don't involve a busted tranny. But I can see why you would say that.
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post #4 of 7 (permalink) Old 02-11-2015, 11:04 PM
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Since the problem occurs with two completely different trans, and the transmission is electronic, I suspect input signals from various sensors/pcm that tell the transmission when to shift. Possibly faulty wiring, bad connection(s).

Throttle plate closed, a 32 mile per hour 3-2 downshift seems a bit high. Check the vehicle speed sensor, throttle position sensor, and mpls. Again, check for faulty wiring, and connections.

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post #5 of 7 (permalink) Old 02-18-2015, 03:45 PM
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One of the family cars when I was a child was a 1979 Pontiac Grand Prix with a rebuilt transmission. When slowing down and coming to a stop, the transmission would jerk. Not just once. It would do it the entire time that you were slowing down.

Thinking back, it seems as if the torque converter kept locking and unlocking. Just thought of this.

Who knows what was really going on.
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post #6 of 7 (permalink) Old 02-18-2015, 09:29 PM
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Quote:
Originally Posted by woodnknots View Post
1996 4.6L with a reman tranny. This happened with the original tranny too, so I gather it is just with this car. When I am slowing down and get to about 32 mph the car downshifts HARD. It's a jolt. Seems like it's the 3-2 downshift. Is this normal? Is there anything I can do to stop it from happening or is it just a quirk that my car has?
Both my 96 Tbird and 93 Mark VIII downshift at that speed. To me it doesn't seem violent or anything, but I do notice at that exact speed on decel and very light accel either the transmission shifts or the torque converter locks/unlocks. Occasionally with a clunk. In both cars BTW.

I'm not sure if it's a characteristic of the tranny, or maybe it's a normal condition that is being exaggerated by worn transmission or motor mounts.

Otherwise, both trannys worked quite well.

I would check the tranny and motor mounts for good measure.

Last edited by 96beaterbird; 02-18-2015 at 09:30 PM. Reason: Clarity
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post #7 of 7 (permalink) Old 02-18-2015, 11:23 PM
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Do you have a tune in that car?

D

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All my vehicles tuned by BC Automotive (me)

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