Trans Downshifts at weird times - Toyota Yaris Forums

sxekevin · 06-27-2011, 11:51 PM

Intermittently the (auto) trans will downshift at weird moments, such as going downhill at higher speeds. Is there a recall for the solenoids on the Yaris or is there a different problem (or just a design flaw)?

Betrivent · 06-27-2011, 11:54 PM

is it downshifting while you're still applying gas? If not, that's the engine gearing down to slow you on purpose.

sxekevin · 06-28-2011, 01:35 AM

No. I will be idling down hill, not at all applying the brake, and it will downshift. I just find it weird that this happens intermittently.

Betrivent · 06-28-2011, 01:36 AM

I don't think that's downshifting actually.. I think that's the DFCO kicking in. (Deceleration Fuel Cut Off). It's built in to help save gas.

TRDMarty · 06-28-2011, 08:53 AM

Quote:

Originally Posted by Betrivent

I don't think that's downshifting actually.. I think that's the DFCO kicking in. (Deceleration Fuel Cut Off). It's built in to help save gas.

sxekevin is right.
My car actually does the very same thing with auto trans.
It appears that the computer knows when you are not applying any
input to the accelerator pedal and as soon as you touch the brake
pedal, the trans will automaticly downshift. It appears to be an aid
in braking. It then stays in the downshift mode until you have applied
acceleration input back to the ''go'' pedal for a period of about 10 seconds
then it will shift back to high gear again.

Bluevitz-rs · 06-28-2011, 09:38 AM

All newer toyotas have this feature built into the auto transmission programming. It's to help slow the car if you're off the accelerator and gaining speed. It even works with the cruise control set.

sxekevin · 06-28-2011, 03:29 PM

That's a good feature for brake assist, and or quicker acceleration, but it goes against fuel mileage, especially while going downhill.

Thanks for the replies btw

R2D2 · 06-28-2011, 03:42 PM

Actually depending on the situation it can save gas because when no throttle is applied and you are engine braking down the hill the fuel injectors are not activated and no fuel at all is used.

If you want to keep momentum down a hill then ever so slight pressure on the accelerator will prevent DFCO/and the downshift.

R2

Bluevitz-rs · 06-28-2011, 04:04 PM

It should really only activate when you push the brake pedal.

Kiteless · 06-28-2011, 04:34 PM

Does the Manual have this fuel cut off? I find that if I coast and downshift the engine braking on the Yaris is better than any other car I have ever ownwed. I always thought it was the compression, but its only like 9.5/1 or something right? 92K miles and still on my original brakes from the dealer.

Betrivent · 06-28-2011, 04:42 PM

Yes, the manual also has DFCO

Kiteless · 06-28-2011, 04:50 PM

Quote:

Originally Posted by Betrivent

Yes, the manual also has DFCO

That also explains the tone change of the engine when coasting, and again, brakes lasting FOR EVAR with my driving style.

- Jason

06-27-2011, 11:51 PM	#1
sxekevin Drives: Blue Yaris Hatchback Join Date: Jun 2011 Location: Illinois Posts: 5	Trans Downshifts at weird times Intermittently the (auto) trans will downshift at weird moments, such as going downhill at higher speeds. Is there a recall for the solenoids on the Yaris or is there a different problem (or just a design flaw)?

06-28-2011, 03:42 PM	#8
R2D2 Crazy Oil Sniffer Drives: MM 09 Yaris 5 Dr LB "Click" Join Date: May 2009 Location: ME Posts: 498	Actually depending on the situation it can save gas because when no throttle is applied and you are engine braking down the hill the fuel injectors are not activated and no fuel at all is used. If you want to keep momentum down a hill then ever so slight pressure on the accelerator will prevent DFCO/and the downshift. R2 __________________ "The howl was the sound of God’s casting pot, the morphing of my cells into shape, the forming of oceans out of molten premordial plasma. And I could feel it. I could cry for it. I could cry with it." -The Fitful One

06-28-2011, 04:34 PM	#10
Kiteless Drives: US 2007 Yaris Liftback 5MT Join Date: Aug 2006 Location: Union City, CA - U.S.A. Posts: 205	Does the Manual have this fuel cut off? I find that if I coast and downshift the engine braking on the Yaris is better than any other car I have ever ownwed. I always thought it was the compression, but its only like 9.5/1 or something right? 92K miles and still on my original brakes from the dealer. __________________ 2007 Toyota Yaris Liftback Base 5 Speed. Mods: Netz/Vitz/RS badging, RS style spoiler, RS replica tails, Tenabe NT210 Springs, Tokico Blue Struts, Team Dynamics 14", fogs(Arrived), JDM HKS Exhaust.

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06-27-2011, 11:54 PM	#2
Betrivent Not quite a noob Drives: e46 325 Join Date: Jul 2009 Location: edmonton Posts: 1,408	is it downshifting while you're still applying gas? If not, that's the engine gearing down to slow you on purpose.

06-28-2011, 01:35 AM	#3
sxekevin Drives: Blue Yaris Hatchback Join Date: Jun 2011 Location: Illinois Posts: 5	No. I will be idling down hill, not at all applying the brake, and it will downshift. I just find it weird that this happens intermittently.

06-28-2011, 01:36 AM	#4
Betrivent Not quite a noob Drives: e46 325 Join Date: Jul 2009 Location: edmonton Posts: 1,408	I don't think that's downshifting actually.. I think that's the DFCO kicking in. (Deceleration Fuel Cut Off). It's built in to help save gas.

06-28-2011, 09:38 AM	#6
Bluevitz-rs 1NZ-6spd View User's Garage Drives: '05 6-Spd Vitz RS Join Date: Oct 2008 Location: Oshawa, Ontario, Canada Posts: 2,967	All newer toyotas have this feature built into the auto transmission programming. It's to help slow the car if you're off the accelerator and gaining speed. It even works with the cruise control set.

06-28-2011, 03:29 PM	#7
sxekevin Drives: Blue Yaris Hatchback Join Date: Jun 2011 Location: Illinois Posts: 5	That's a good feature for brake assist, and or quicker acceleration, but it goes against fuel mileage, especially while going downhill. Thanks for the replies btw

06-28-2011, 04:04 PM	#9
Bluevitz-rs 1NZ-6spd View User's Garage Drives: '05 6-Spd Vitz RS Join Date: Oct 2008 Location: Oshawa, Ontario, Canada Posts: 2,967	It should really only activate when you push the brake pedal.

06-28-2011, 04:42 PM	#11
Betrivent Not quite a noob Drives: e46 325 Join Date: Jul 2009 Location: edmonton Posts: 1,408	Yes, the manual also has DFCO