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Discussion Starter #1
I searched, but most tranny threads seem to deal with later models. I have an 83 and the transmission started shifting differently today. It downshifts way too soon with just a little throttle, and then won't upshift until it pushes 4000 rpms or I let my foot off the gas. It is dark and snowing right now, so I did not investigate much and was hoping some folks with more C6 knowledge than myself can point me in the right direction or diagnosis. My first thought was to check fluid level and linkage, but don't know if I am on the right track.

Any pointers or thoughts would be appreciated.
 

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Your kind of on the right track, always keep an eye on tranny fluid. if thats all good, then you might have a vacuum leak.
underneath on the pass. side is a round "modulator" (about the size of a shot glass in circumference) and it has a rubber long hose on it leading to the intake of the engine. this controls shift points. check it for connection or cracks.
 

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Discussion Starter #3
Thanks for the reply. I've got no defrost and a current leak near the brake pedal that goes away when you hit the brakes, so a vacuum issue would be par for the course at this point and number three on the vacuum list to check in the next couple days.

I'll post back what I found so the next knucklehead like me with a new Bronco can find something in search if they have the same issue.
 

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I'm pretty sure vacuum module only controls up shift points and not down shift ponits. If fluid level is good and vacuum leaks don't fix your problem, I'd change out the vacuum module.
 

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Discussion Starter #5
Follow up:

Fluid was low. Topped off with Type F (oops ... what my buddy who I bought it from but doesn;t know much about vehicles had in the console and said he checked was the right type).

Improvement, but still not quite right. I had high RPM idle, blamed it on the cold weather that rolled in and a sticking choke, so, getting onto freeway today, I floored it (trying to get choke to turn off) and ended up with a stuck throttle wide open. Yikes.

Turns out the kickdown linkage had come off at the carb, and that caused the throttle on the side of the carb to hang up on the bottom of the air cleaner cover, keeping the idle high the last two days and also influencing updhift. So, if anyone else searches with the same problem, check your fluid and linkage as both were causing my problems.

Good to know about the vacuum deal as well, as I have some vacuum issues too ...

Thanks.
 
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