Downshift when turning corners - Miata Forumz - Mazda Miata Chat Forums
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NA (1989-1997) NA Miata discussion within. The MX5's first generation, the NA, sold over 400,000 units from 1989 to 1997.

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Old 02-28-2012, 02:31 PM   #1
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Default Downshift when turning corners

Weird problem happening. Sorry about posting alot of questions lately. My 92 sat up for 3 years and now it's back in the game.
Problem is not without many little nuances.

My new problem today is it automatically downshifts when turning corners (I have an automatic). Just started doing this today. Don't know if this is related but after a cold start in the mornings I put it in reverse and it rolls back about 15 ft. each time and then just sits there. I let off the gas and punch it and it jumps back into backing up.
Acts fine the rest of the day, except turning corners.

Wierd issue.
Anyone ever heard of this craziness?
Thanks
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Old 02-28-2012, 02:52 PM   #2
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Gotta be honest, the rolling back thing is a new one to me. I thought the automatic was designed to downshift when cornering. Is it bringing the engine to a high rev?
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Old 02-28-2012, 03:05 PM   #3
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I have no clue, never even seen an automatic miata in my life.
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Old 02-28-2012, 06:29 PM   #4
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Automatic transmissions sense manifold vacuum, input shaft speed (with the governor) and usually a cable attached to the throttle to measure its opening. Wide open throttle + low vacuum + low governor speed + downshift. Closed throttle + high vacuum + low governor speed = downshift, also. High governor speed = upshift (but upshift can be earlier or later due to vacuum).

Clear as mud?
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Old 02-28-2012, 10:24 PM   #5
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Whats this fancy automatics transmission thing your talking about??


In all honesty, sorry, I dont work with or drive auto trans for a reason. I cant help you here.
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Old 02-29-2012, 09:12 AM   #6
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Quote:
Originally Posted by sixshooter View Post
Automatic transmissions sense manifold vacuum, input shaft speed (with the governor) and usually a cable attached to the throttle to measure its opening. Wide open throttle + low vacuum + low governor speed + downshift. Closed throttle + high vacuum + low governor speed = downshift, also. High governor speed = upshift (but upshift can be earlier or later due to vacuum).

Clear as mud?
So six your saying this is or could be a vaccum leak?
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Old 02-29-2012, 02:25 PM   #7
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Easy fix, buy a manual trans.
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Old 02-29-2012, 02:54 PM   #8
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Low on trans fluid? Filter clogged?
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Old 03-01-2012, 07:04 AM   #9
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Quote:
Originally Posted by shultzee13 View Post
So six your saying this is or could be a vaccum leak?
A vacuum leak could manifest itself in that fashion.

I was just throwing out some basics of automatic transmission shift modulation so that you could understand what outside elements act upon it and possibly decipher the root cause. A vacuum leak is an excellent thing to look for in this case. And it is easy/cheap to look for.
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Old 03-01-2012, 07:06 AM   #10
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the AT connects to the back of the intake manifold almost right under you fuel pressure regulator. where it goes from there idk.
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