hesitation problem - Toyota Yaris Forums

larryn2o · 07-16-2011, 04:48 PM

is there a cure for a hesitation just off idle? car has done it since new and is getting worse. it feels like the torque converter is disengaging and will make the car lunge forward unexpectedly.

thanks

Liu997 · 07-16-2011, 06:50 PM

Yeah, mine has been doing it since new also. I don't think there is a way around it. It is especially bad when nearly stopping from a high speed and accelerating again.

I believe that the transmission is just downshifting. There is no way to eliminate the effect but I noticed when I changed the transmission fluid that it is slightly less problematic.

thepartsmancometh · 07-17-2011, 12:48 AM

sometimes, issue like this can be a "learned" response from the ECU. I had our master tech check my wife's yaris out because of a throttle hesitation (or, more accurately, a lack of sensitivity). We tried everything: swapping the gas pedal, swapping the t-body, etc. I finally fixed it by unhooking the battery (for an unrelated install) and resetting the ECU. its worth a shot.

CTScott · 07-17-2011, 07:58 AM

+1 on the learned response.

After installing my supercharger I reset the AT memory in the ECM (this can only be done with the TechStream tool) and it made a huge difference on how and where the transmission shifts. The AT learning occurs during the first 15 minute drive cycle, so even when buying a new Yaris it is possible to miss that opportunity if the dealership does a checkout drive with your car.

Unplugging the battery for a couple of minutes will reset the short term fuel trim, but will not reset anything in regards to the transmission.

larryn2o · 07-20-2011, 09:46 PM

thanks for the feedback , sounds like i need to get ahold of a Techstream tool.

bronsin · 07-21-2011, 06:24 AM

My Yaris (and my wifes 2005 Camry) do not make smooth transitions when they start moving. You have to push on the gas pedal quite a bit and even then the car doesnt move right away. When it does it tends to be faster than you would like because you have pressed the gas pedal so far to initiate movement.

Is this the same thing you guys are talking about?

And will resetting the transmission help?

WHat is this Techstream tools so I can look it up on the internet?

Thanks!

CTScott · 07-21-2011, 06:31 AM

Quote:

Originally Posted by bronsin

My Yaris (and my wifes 2005 Camry) do not make smooth transitions when they start moving. You have to push on the gas pedal quite a bit and even then the car doesnt move right away. When it does it tends to be faster than you would like because you have pressed the gas pedal so far to initiate movement.

Is this the same thing you guys are talking about?

And will resetting the transmission help?

WHat is this Techstream tools so I can look it up on the internet?

Thanks!

The deadband on the throttle is mostly due to the drive by wire throttle, and that is significantly helped by a throttle controller, like cammell is talking about.

How the AT shifts between gears is the part that is learned by the ECM. The TechStream tool is Toyota's computer based diagnostics tool.

bronsin · 07-21-2011, 10:32 AM

How do you install it? Where does it go!

And where can I get one?

bronsin · 07-21-2011, 11:03 AM

pm sent

camelll · 07-21-2011, 07:47 PM

Sorry guys the throttle controller is sold.

07-16-2011, 04:48 PM	#1
larryn2o Drives: 08 yaris Join Date: Nov 2010 Location: MS Posts: 51	hesitation problem is there a cure for a hesitation just off idle? car has done it since new and is getting worse. it feels like the torque converter is disengaging and will make the car lunge forward unexpectedly. thanks __________________ http://www.youtube.com/watch?v=izq4B5Q5oLQ http://www.youtube.com/watch?v=_pvT1QTy9WI http://www.youtube.com/watch?v=PYf5W9CLQ1I

07-17-2011, 07:58 AM	#4
CTScott ULTIMATE View User's Garage Drives: 09 5dr LB, 2x 08 3dr LB Join Date: Oct 2008 Location: USA, CT Posts: 13,460	+1 on the learned response. After installing my supercharger I reset the AT memory in the ECM (this can only be done with the TechStream tool) and it made a huge difference on how and where the transmission shifts. The AT learning occurs during the first 15 minute drive cycle, so even when buying a new Yaris it is possible to miss that opportunity if the dealership does a checkout drive with your car. Unplugging the battery for a couple of minutes will reset the short term fuel trim, but will not reset anything in regards to the transmission. __________________

07-20-2011, 09:46 PM	#5
larryn2o Drives: 08 yaris Join Date: Nov 2010 Location: MS Posts: 51	thanks for the feedback , sounds like i need to get ahold of a Techstream tool. __________________ http://www.youtube.com/watch?v=izq4B5Q5oLQ http://www.youtube.com/watch?v=_pvT1QTy9WI http://www.youtube.com/watch?v=PYf5W9CLQ1I

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07-16-2011, 06:50 PM	#2
Liu997 Drives: 2008 Red Yaris LB Join Date: Nov 2008 Location: Hicksville, LI Posts: 125	Yeah, mine has been doing it since new also. I don't think there is a way around it. It is especially bad when nearly stopping from a high speed and accelerating again. I believe that the transmission is just downshifting. There is no way to eliminate the effect but I noticed when I changed the transmission fluid that it is slightly less problematic.

07-17-2011, 12:48 AM	#3
thepartsmancometh Drives: '08 LB, '07 WRX Join Date: Jan 2009 Location: midwest Posts: 187	sometimes, issue like this can be a "learned" response from the ECU. I had our master tech check my wife's yaris out because of a throttle hesitation (or, more accurately, a lack of sensitivity). We tried everything: swapping the gas pedal, swapping the t-body, etc. I finally fixed it by unhooking the battery (for an unrelated install) and resetting the ECU. its worth a shot.

07-21-2011, 06:24 AM	#6
bronsin Drives: 2009 Base Hatch 2 Dr Auto Join Date: Dec 2008 Location: nj Posts: 4,790	My Yaris (and my wifes 2005 Camry) do not make smooth transitions when they start moving. You have to push on the gas pedal quite a bit and even then the car doesnt move right away. When it does it tends to be faster than you would like because you have pressed the gas pedal so far to initiate movement. Is this the same thing you guys are talking about? And will resetting the transmission help? WHat is this Techstream tools so I can look it up on the internet? Thanks!

07-21-2011, 10:32 AM	#8
bronsin Drives: 2009 Base Hatch 2 Dr Auto Join Date: Dec 2008 Location: nj Posts: 4,790	How do you install it? Where does it go! And where can I get one?

07-21-2011, 11:03 AM	#9
bronsin Drives: 2009 Base Hatch 2 Dr Auto Join Date: Dec 2008 Location: nj Posts: 4,790	pm sent

07-21-2011, 07:47 PM	#10
camelll Drives: 07 sedan Join Date: Jun 2007 Location: Home Posts: 108	Sorry guys the throttle controller is sold.