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Old 04-30-2001, 11:24 AM   #1
Joncas
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Post Auto downshift in 4Eat

My auto downshifts from 4th to 3rd sometimes when i just tap the brake. But I can't seem to figure out what the deciding factor is for the car to do it. Anyone have this figured out.

Ok same note, sometimes once it does it the transmission stays in 3rd for like 30 or 40 seconds before going back to 4th. Normal?

I know one of you knows this stuff.

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Old 04-30-2001, 11:44 AM   #2
Blindeye_03
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auto trannies are w--e--i--r--d...

This is my first 5speed(my impreza) & I love it soooooo much more!! .

---edit---
spelling

[This message has been edited by Blindeye_03 (edited May 01, 2001).]
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Old 04-30-2001, 01:36 PM   #3
grimlock
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Probably a little logic the FHI engineers put in to allow for engine braking with the auto tranny. Try decelerating a few different ways to see what the tranny does.

First, try getting to about 40mph and snapping off the gas, but not hitting the brake. Does the tranny downshift? Try this on level ground and while going down a hill.

Second, if the tranny downshifted the first time, try easing off the gas and see if it does. It probably won't.

Third, if the tranny didn't downshift the first time, try snapping off then gently squeezing the brake. If the first case didn't make it shift, perhaps this will.

Bear in mind that I have no idea whether this will actually work, it's just what I'd try to do if I were programming the shifting algorithms for an electronically controlled auto tranny and had access to all sorts of sensor readings. Hope this rambling helps...

Ross N.
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Old 04-30-2001, 02:04 PM   #4
KITTbri
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ross you have no clue... you're talking out of your a$$...

seriously though... it will downshift on hills when light braking, tapping, the brake pedal... mine does it all the time, but only at higher speeds on longer hills... it will also do it when cresting a hill under heavy throttle when i lift off the gas... this is due to "fuzzy logic" in the TCU. all perfectly normal... it usually happens in respnse to me tapping the brake or light braking on the backside of hill... it will stay in 3 until the TCU realizes the best efficiency is back down to 4/D.

sometimes you can trick the TCU but it is diffucult...

don't listen to ross he has a mannie...
-brian-
"has stick envy"
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Old 04-30-2001, 03:12 PM   #5
Overtime
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As far as I know, the trannies adapt to your driving style. Thus, if you're always gassing it as soon as you let off the gas, it engine brakes some.
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Old 04-30-2001, 04:07 PM   #6
grimlock
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Have a Nice Day?

Yeah, well at least I can keep my car out of peoples' front yards...
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Old 04-30-2001, 04:11 PM   #7
WRX1
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Wgat is happening is that the locking torque converter is unlocking when you tap on the brakes (this allows the motor to freewheel). All cars with locking torque converters do this. If you watch your tach, the rpm should go up only about 300-500 rpm, where as if it downshifted, it would go up about 1000 or so.
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Old 04-30-2001, 04:26 PM   #8
Joncas
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Trust me, its down shifting. If I throw the lever in third nothing changes. Good idea, but defintely not a torque converter becoming hydrostatically uncoupled.
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Old 04-30-2001, 11:54 PM   #9
ivbdn
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That's the way it's designed. When you press the brake, it automatically downshifts to 3rd. It becomes the default gear during braking. I'm not too sure of the purpose, but I think it's so that when you get back on the gas, you won't have to wait so long for it to respond.
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Old 05-01-2001, 06:06 AM   #10
Blindeye_03
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Quote:
Yeah, well at least I can keep my car out of peoples' front yards...
Sounds like STORY time .
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Old 05-01-2001, 09:25 AM   #11
remarcable
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I think there was actually a TSB out for the 99 Outbacks that SOA put in a chip that was too sensitive and over-used engine braking on slight inclines. I believe it is supposed to start using engine braking heavily ONLY when you slam on the brakes and the computer senses that the wheels are in ABS mode and yet the speed of the car is not being reduced.

It's never bothered me and it is nice to have it in 3rd when I am ready to get back on the gas.
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Old 05-01-2001, 01:33 PM   #12
KITTbri
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Talking

blindeye - (oh i love this)do a search!!!
look under "how to drive like an idiot"

-brian-
"drives like an idiot"
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Old 05-02-2001, 12:27 AM   #13
subymamma
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Do you have your Subaru book (manual)? If you look in the section on transmission, I believe it will refer to this in there.
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