Laggy auto transmission

[toml]

Hi again - I searched around but couldn't find much relevant info on my AT problem (plus I wanted my own thread! )


Anyway... Accelerating from stand still my car is very.. nonlinear. As I press the accelerator smoothly, sometimes (not always) the car will rev to around 1900rpm before actually kicking into gear with a big jerk forward.

I assume this isn't normal. Now, pretend I don't know anything about how an auto transmission works (hehe, pretend )... any ideas what it could be?


Tom


ps. Now that I think of it, most gear changes seem to be a bit of a 'jerk' instead of a nice smooth transition...

 

[koulee]

It should be a very smooth transition, but thats only with brand new trannys and low mileage trannys.

Some things to do:

Have the trans flushed and the oil strainer replaced
Adjust the throttle cable

When I still had my 92 AT Turbo, the tranny shifted like new, then again it only had about 40k miles on it.

 

[toml]

The throttle cable... do you mean the actual accelerator cable or the one that goes to the tranny?

Is there an actual proceedure for adjusting or checking those cables, or does everyone just eyeball it?

 

[Allan_MA70]

99% chance your auto is fucked

 

[toml]

99% chance your auto is fucked

"fucked" is very descriptive but really doesn't tell me why/how/what is broken....

 

[Allan_MA70]

without hearing it i would say 2nd gear is dead as the supra go's 2nd then 1st when you take off to make it smoother... tryed pulling it into L ?

 

[koulee]

The throttle cable... do you mean the actual accelerator cable or the one that goes to the tranny?

Is there an actual proceedure for adjusting or checking those cables, or does everyone just eyeball it?

See if the tranny is throwing any codes at all first:

http://www.cygnusx1.net/supra/library/TSRM/at/AT_014.html

Checking to see if the throttle cable is correctly adjusted:

http://www.cygnusx1.net/supra/library/TSRM/at/AT_019.html

For our trannys, the a340e, the throttle cable controls the line pressure in the tranny which controls how much fluid pressure there is. If the cable is off, it will be whack and you will have lots of noticeable shift shock or slippage.

Other things that can go wrong are dying solenoids which control the upshift and downshift.

 

[Doward]

5 speed swap ftw.

That's what I'm doing.

Things to try -

Check the damn fluid level, warmed up, car running.

When I got my '88 Turbo, the auto did all kinds of random shit (it would downshift and never upshift, for instance)

I flushed it out with 14 qts of Toyota's Type IV ATF - works like a damn charm now! Perfect shifts and everything!

 

[iwannadie]

See if the tranny is throwing any codes at all first:

http://www.cygnusx1.net/supra/library/TSRM/at/AT_014.html

Checking to see if the throttle cable is correctly adjusted:

http://www.cygnusx1.net/supra/library/TSRM/at/AT_019.html

For our trannys, the a340e, the throttle cable controls the line pressure in the tranny which controls how much fluid pressure there is. If the cable is off, it will be whack and you will have lots of noticeable shift shock or slippage.

Other things that can go wrong are dying solenoids which control the upshift and downshift.

what do you use to connect the terminals as mentioned in the manual? just wire and gator clips?

 

[koulee]

You have to use the following Special Service Tool (SST):

http://www.officedepot.com/textSear...gv4cgjt?uniqueSearchFlag=true&Ntt=paper+clips

 

[toml]

I checked the transmission codes - nothing.

It's got fresh fluid in there, synthetic dexron III.

That TSRM proceedure to check the throttle cable - I assume that's checking the throttle cable where it connects to the tranny, not where it connects to the throttle body? I'll test that on the weekend and flush out the fluid again..

Allan, from what you describe that sounds about right - the TSRM seems to think it could be the valve body, the electronic control system or the solenoid valve(s)...

Tom

 

[koulee]

I checked the transmission codes - nothing.

It's got fresh fluid in there, synthetic dexron III.

That TSRM proceedure to check the throttle cable - I assume that's checking the throttle cable where it connects to the tranny, not where it connects to the throttle body? I'll test that on the weekend and flush out the fluid again..

Allan, from what you describe that sounds about right - the TSRM seems to think it could be the valve body, the electronic control system or the solenoid valve(s)...

Tom

Where it connects to the throttle body. With the engine off, open the butterfly to WOT. There's a stopper on the throttle cable that should only peek out 0 - 1 mms from under the rubber boot.

 

[dbsupra90]

Where it connects to the throttle body. With the engine off, open the butterfly to WOT. There's a stopper on the throttle cable that should only peek out 0 - 1 mms from under the rubber boot.

yes sir.

ive talked about this many times and made a picture just for this occasion

you want the crimp on the cable where the red arrow is at wot. it makes a big difference in how the tranny behaves.

 

[toml]

Oh, right I wasn't aware of this! I'll have to have a look when I go out to the car. Thanks guys.

 

[theKnifeArtist]

dont wanna be jackin no threads but quick question. are all automatic tranny fluids alike? i due for a change and wanna know what fluid to get.

 

[toml]

I've been told that all Dexron III fluids are the same (close enough, anyway, that's how they get the Dexron III label)... so as long as you stick to one of those you'll be fine.

 

[toml]

Ok my little stopper on the transmission throttle cable was about 4mm away from the end of that rubber thing, so I've adjusted it so its right at the end and went for a quick test drive. Seems better so far! I'll see how it goes later tonight

 

[Doward]

I prefer the Toyota Type T-IV ATF over the Dexron...

 

[toml]

My transmission shifts really slow and hard from 3rd gear to O/D (4th).

I notice this mostly in the mornings on the way to the swimming pool which has a 100 km/hr section up a hill. With cruise control on, set to about 108km/hr, it kicks from overdrive down to third gear when I hit the bottom of the hill, when I reach the top of the hill it switches to overdrive again with a big THUD.

In the mornings, when the car+engine are cold, I also notice what seems to be the transmission either skipping third or sticking in fourth. After the transmission warms up (maybe 3 to 4minutes of slow and easy driving), it 'toughens up'. I know, poor explanataion, but I can't work out how to describe it!

Could these be related? What could be the cause?

Thanks

 

[jdub]

Did adjusting the throttle cable have a big impact? Is the cable sticking?

Sounds like you may have a solenoid sticking or has crap in it.