New Corolla auto - occasional rough shifts

[ADH]

I have a brand new 2006 Ascent Auto. For the first 3 weeks everything was fine (approx 1200 KM) and then the last 2 weeks I have been noticing the occasional rough shift or miss-shift. Fluid level is normal.

Most often this will happen going up a hill in peak hour traffic. You a crawling along at 10 KM/H up a hill and as you touch the accelerator to move along you will get a rough shift as the drive engages. It has also happened moving from a standing start going down a hill. The transmission seems to spin free for a second then engage hard or roughly. Air conditioner is ON.

95% of the time everything is fine and I cannot replicate the problem on demand.

Are these transmissions adaptive ? Is this normal and will it settle down ? I was expecting the transmission on the car to be flawless but currently, it isn't.

Advice appeciated.......

Edit: Sorry, wanted to put this in Corolla section but didn't by mistake

Edited March 28, 2007 by ADH

[negatron]

complain to toyota before u do anything else, its a new car so get it on record that its acting up.

i never had this happen and my old ascent had racked up 50ish thousand kms...

[Saiya]

Hrrrm Ive got a 06 auto and I dont think ive come accross that problem.

With mine if I push on the accelerator a tad down too much theres a brief pause until its like the engine "kicks" in then you feel a sharp bump as the car is taking off. You just gotta find the sweet spot so it doesn't do that.

The thing is if I floor the accelerator from standstill I do not get this issue.

Get Toyota to have a look at that issue, does not sound normal at all.

[ADH]

Spoke to Toyota and as I expected, unless I can reproduce the problem on demand, it is a waste of time bringing the car in

However, I am coming to some conclusions about this issue and believe the problem could be caused by overheating ATF (auto trans fluid). Problem arises in the following conditions:

- coming off motorway after running in overdrive (makes trans nice and hot because there is a fair amount of slip in O/D) and get stuck in stop/start traffic (stop/start very hard on ATF, made worse being on a hill and because there is no airflow through radiator which contains ATF cooler)

- I ALWAYS run the aircon which is a dealer-fitted unit not a factory-fitted unit (this worried me when I bought car 5 weeks ago). I am thinking they fit big ones to Australian cars because the heat exchanger sitting in front of the radiator is MASSIVE and is as big as the radiator itself (4 times the size of the one on my old commodore ). According to various cooling sites I visited, the radiator/ATF cooler effciency could be reduced to as little as 75% when the aircon is running

- my symtoms (delayed engagement followed by harsh engagement if the above conditions are met) could be explained by torque converter problems caused by overheating ATF in a transmission that shifts beautifully at all other times (ie. assuming no mechanical problem). Torque converter shudder (I get this in overdrive too) is also a characteristic symptom. Ford trucks have quite a few TSBs on this issue and FORD will fit a free auxiliary ATF cooler for trucks experiencing shudder in overdrive

- the A245E trans has a small ATF reservoir (2.9L) and is quite hard on ATF from what I have read. Other cars that have Aisin-Warner auto transmissions are the same. Also, the OEM ATF cooler in the radiator does very little from what I have read (at most 10% ATF cooling compared to after market coolers which can do as much as 60%)

So, I will have to experiment. It is getting cooler now as winter approaches and I will not use the aircon for a while and will do an ATF change. I will see if the problem reoccurs. If it doesn't, I will assume I have found the reason and will get my trans guy to fit an auxiliary trans cooler (very cheap). In fact, additional trans coolers are so cheap and can protect the ATF so well, you might as well do it anyway.

Of course, I could be wrong as I have a hard time explaining why this would happen in a new Corolla with a reputation for reliability and in a transmission that Toyota say can run forever on the factory fill of T-IV ATF (I could write another thread on this issue alone ....). Toyota don't even sell an auxiliary ATF cooler with their 950KG tow pack for the Corolla. I doubt I would be the only one with this problem however, from what I am told, I could easily be the only one sensitive enough to be worried by it

[Rolla_Boy]

i rented a 2006 or 2005 corolla auto accent couple weeks ago and i had the same problem with miss shifts it just wouldnt change.

Only when it was cold

[shmicko]

not sure, never happened to me.

[Saiya]

ADH what state are you in?

[ADH]

ADH what state are you in?

NSW

ps Does anyone know if the differential and transmission share the same fluid or is the fluid on the 2006 auto separate ?

[CAP]

The transmission seems to spin free for a second then engage hard or roughly.

That sounds like it's slipping.

When you check the oil level, are you checking it hot or cold? Auto Trans oil levels should always be checked hot.

If you forget to do it just after driving the car, there's another way to check the level from your driveway.

To do so, open your bonnet, start the car and allow to idle a minute in P or N. Then with your foot on the brake, place the car in D, leave for a couple of seconds, then move to R, leave for a couple of seconds and return to D. Repeat this 4 - 5 times with your foot on the brake (Even if the handbrake is on).

When you've repeated this 4-5 times, return to P and check the oil level quickly (Remember - pull out the dip stick, wipe clean then put right in again and pull out) The oil level should be between the two marks on the dip stick.

[ADH]

I've been checking the ATF levels regularly, while hot, and it is between the two hot notches as expected. I concur that there is more slip in the transmission while hot, what feels like the converter to me. It is too bad there is no Toyota-certified T-IV synthetic ATF that you can use under warranty because synthetic ATF often fixes quality issues.