engine load sensor controlling gearbox?

[allante666]

Hi

2000 2.5 legacy. Auto. Is there some sort of sensor that measures engine load which controls the gearchange points? MIne just seems to change at strange points sometimes. Often if im coasting down a hill it will change down a gear. If Im cruising on the flat and I floor it, instead of dropping straight into like 2nd it will change down through the gears to get there, ok, very quickly but if you need to take off quick you have to wait a second or so while it changes down.

Is this normal?

Or, is there a seperate ecu for the gearbox which i need to reset?

[Kiwi GT]

The TCU (transmission control unit) is a separate computer to the ECU and can be reset. I can't for the life of me remember how to do it without a Select Monitor. I'm not sure that flicking the battery leads off for a while will work or not.

Anyway, the TCU takes inputs from the TPS, MAF etc to calculate engine load and decide shift points.

[allante666]

Well after all the trouble I had curing my lumpy idle (which turned out to be the valve clearances), most sensors etc have been checked and set up correctly. I have a BMW and the gearbox on those always benefits from a gearbox ecu reset so wondered if subarus were the same.
I only have ecuexplorer though.
Do the symptoms sound like it could be that?

Sometimes I can floor it up a long hill and it will stay in 4th and then when I take my foot off and go downhill I expect it to drop into 5th but it doesnt. Other times I can cruise downhill and it will change down a gear suddenly and i get engine braking, which is handy but unexpected!
Its the slow kickdown that bugs me though.

(im assuming here its a 5 speed but if its a 4 speed just deduct a gear!!)

[Kiwi GT]

2000 will be a 4 speed. When was the last time you flushed the transmission fluid and changed the spin-on filter? New fluid can work wonders.

[allante666]

Never changed the fluid, only got the car about a month ago and dont know if it had been done by any previous owner, theres nothing in any of the history about it.

What spin on filter??

[Kiwi GT]

There should be a spin on trans fluid filter on the front bottom LH side of the trans case.

You can see it in this pic...

https://sl-i.net/FORUM/images/imported/2010/11/4eat-1.jpg

[allante666]

Ah ok the black thing there. So if I change the fluid, whats th ebest way of doing it? is there a filter inside the sump I need to be changing as well or is this canister one replacing the normal gauze filter inside? Is it just a drain and refill job or is there anything I should be doing in particular?

[Kiwi GT]

The sump filter is just a strainer to filter out the larger items of debris.

I like to drain, replace the filter, and refill, go for a 5 min drive, drain and refill again, another short drive, and then a final drain and refill. A drain only drops about 4 litres of fluid, whereas a 4EAT holds around 12L total, so it needs to be done a few times to completely flush it.

[allante666]

Dexron 2 or Dexron 3?

[Kiwi GT]

Possibly DX3, but possibly something else too. Check your owners manual on fluid spec. Here in NZ we use a Castrol fluid, LE95 for the 4AT up to MY06, and Transmax E for MY07 on and for all 5ATs.

[jewbaru]

so does anyone know the sequence to reset this without a computer?

[jewbaru]

if not i have access to a modis, solus, and the verous. im not to keen on any of them, so if theres just a simple way of resetting it id perfer that method.

[ouch1011]

The downshifting thing (where it downshifts through all the gears) is normal, I've noticed that about the phase 2 transmissions. They downshift very slowly compared to the phase 1 trans I had. I suspect they had durability issues from trying to downshift too quickly on the phase 1 transmissions, Ford had the same issue on their 4R70W.

[Huffer]

Ah ok the black thing there. So if I change the fluid, whats th ebest way of doing it? is there a filter inside the sump I need to be changing as well or is this canister one replacing the normal gauze filter inside? Is it just a drain and refill job or is there anything I should be doing in particular?

If it's never been done, I like to drop the whole pan and clean it out, then reattach and use fresh fluid. I usually do this during the summer so the fluid stays fairly runny. Otherwise, you have to heat the garage to around 75F.

[ouch1011]

Or take the car for a short drive 1st :)