How often should I turn on overdrive?

B

billsauce

New member
Hey guys,

I just got a '99 4runner and I was wondering how often I should have overdrive on. I drive it as a commuter car, and I drive it in the city and sometimes on the highway. I hear that it gives better fuel efficiency? I'm not sure, so I was hoping you guys could help me out. Thanks.
 
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I believe your suppose to leave it on at all times. The only time you want to turn it off is when your towing something or have a heavy load in the car or even 5 passengers. The reason for turning it off is that it allows your engine to rev higher so that you get more TQ.
 
Ya it should already be on, if it's on u get slightly better mpg but not much I only turn it off when i go up a steep hill or towing. Also there is a button right next to the rear defrost button it's called ECT and also allows for more power I use ECT more often because I feel a little more power than overdrive off.
 
The question should be "when should i turn it OFF?", not ON. Leave it on and let it do its thing. Only turn off when towing something of significant weight.

Thats why it has an indicator light for OD Off (exception to normal), instead of OD On.
 
T4R_Finally said:
The question should be "when should i turn it OFF?", not ON. Leave it on and let it do its thing. Only turn off when towing something of significant weight.

Thats why it has an indicator light for OD Off (exception to normal), instead of OD On.
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Yuppers. Only turn it off when necessary. If your transmission is hunting or under a lot of strain. It can also greatly reduce transmission temperatures.
 
I leave OD and ECT on at all times.
I find ECT on lets the engine rev a bit higher before it shifts (closer feeling to a standard tranny).
I only turn OD off when i go up big hills or want to manually downshift....
 
Greg_Canada said:
I leave OD and ECT on at all times.
I find ECT on lets the engine rev a bit higher before it shifts (closer feeling to a standard tranny).
I only turn OD off when i go up big hills or want to manually downshift....
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I do exactly the same. STEEP hills at 50 mph seem to be my 4Runners weak point, OD OFF cures that.

On a side note, welcome to the forum, Greg. I think I've messaged with you a bit on YT in the past.
 
I use it while Merging onto the interstate, and sometimes as a downshift to slow down, or when i want to pass a jeep or something :lookout:
 
Leave OD on. You really only need to turn it off if you are towing a heavy load where the transmission wants to downshift. Turning it off when towing will put less stress on the gears and clutch plates from constantly up and downshifting. OD is mostly affected at higher speeds when towning too. 40+ mph.

AS far as ECT goes, it's a normally off function. You shouldn't really need to turn it on, unless you are towing and want to stay in a gear longer to keep your speed up. As far as just turning it on to move up to higher RPMs... you don't really gain much as far as acceleration is concerned. Yes it will stay in the gear longer, but this is a function in which the computer controlls the shifting points in the transmission to best suit your current towing / added vechile weight / ascending loads. If you leave it on for normal driving you'll mainly just be wasting fuel. Even in passing a car, it's not really needed unless you have added weight. Most people think your engine makes the most power at redline... which is not true. Redline is the limit at which your engine can rev without producing damage to the mechanical components. You can play around with the ECT and see that the computer will shift the transmission earlier than redline with ECT on if you're not depressing the pedal to wide open throttle. Just saying that staying away from redline will help prolong a good strong lasting engine. Looking at the torque and hp specs the v6 will probably make the most power around 4500 rpms. If anyone has dynoed their T4R they could tell you peak RPM power.

Hope this helps.
 
Yep, I'm similar to you guys. I only turn OD off when towing the boat. It helps the tranny from having to continually shift.
As for ECT, I leave it off. I read a while back that some people leave it on, so I tried that. I ended up losing an mpg or two. Once I turned it off, they came back.
 
86SupraMKII said:
Leave OD on. You really only need to turn it off if you are towing a heavy load where the transmission wants to downshift. Turning it off when towing will put less stress on the gears and clutch plates from constantly up and downshifting. OD is mostly affected at higher speeds when towning too. 40+ mph.

AS far as ECT goes, it's a normally off function. You shouldn't really need to turn it on, unless you are towing and want to stay in a gear longer to keep your speed up. As far as just turning it on to move up to higher RPMs... you don't really gain much as far as acceleration is concerned. Yes it will stay in the gear longer, but this is a function in which the computer controlls the shifting points in the transmission to best suit your current towing / added vechile weight / ascending loads. If you leave it on for normal driving you'll mainly just be wasting fuel. Even in passing a car, it's not really needed unless you have added weight. Most people think your engine makes the most power at redline... which is not true. Redline is the limit at which your engine can rev without producing damage to the mechanical components. You can play around with the ECT and see that the computer will shift the transmission earlier than redline with ECT on if you're not depressing the pedal to wide open throttle. Just saying that staying away from redline will help prolong a good strong lasting engine. Looking at the torque and hp specs the v6 will probably make the most power around 4500 rpms. If anyone has dynoed their T4R they could tell you peak RPM power.

Hope this helps.
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Going to have to disagree with you here.
I've noticed it makes NO difference at WOT, it only makes a difference at part throttle (where it will rev to 22-2500 rpm instead of 2000 rpm before it shifts)... this actually returns BETTER mileage because once it hits the next gear, it is not struggling so hard to accelerate from such a low RPM. It feels more like a standard tranny (with the A340H, it needs all the help it can get).

BTW, last few tanks were 10.7 L/100km average.... (22 US MPG) calculated the good ol' fashioned way. This is a limited 4runner with people and gear and a 150lb sub box, roof racks and push bar, average highway speed 65-70mph... definitely not affecting my mileage. EPA is 13.7l/100km or 17mpg.... i'm doing pretty well...
 
A.Wilson013 said:
I do exactly the same. STEEP hills at 50 mph seem to be my 4Runners weak point, OD OFF cures that.

On a side note, welcome to the forum, Greg. I think I've messaged with you a bit on YT in the past.
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Thanks bud, yep i remember your handle...

Admin had to manually make my account for some reason... been lurking for a bit, seems they have the most 5th gen info here :)
 
OD Off basically tries to keep your truck in 3rd. You only want to use it when towing have a bunch or people in the rig or going down a canyon as a way to stay off your brakes. As for ECT leave it off you will lose the MPG I did the test and lost 1-2 as well. Some people say with bigger tires you want it on. I have 33"s and thats total BS it just increases the shift points so you can hold rev's longer and thats a waste since I don't think any of us race our trucks? Well atleast I hope not haha
 
Yeah all OD OFF does is keep the runner from shifting into its top gear. Like everyone else said, better for towing, hills, etc...
 
Overdrive is just 4th gear on these automatics.

It's not different than me shifting from 4th to 5th on my manual transmission because it is less than a 1:1 ratio.
 
Greg_Canada said:
Going to have to disagree with you here.
I've noticed it makes NO difference at WOT, it only makes a difference at part throttle (where it will rev to 22-2500 rpm instead of 2000 rpm before it shifts)... this actually returns BETTER mileage because once it hits the next gear, it is not struggling so hard to accelerate from such a low RPM. It feels more like a standard tranny (with the A340H, it needs all the help it can get).

BTW, last few tanks were 10.7 L/100km average.... (22 US MPG) calculated the good ol' fashioned way. This is a limited 4runner with people and gear and a 150lb sub box, roof racks and push bar, average highway speed 65-70mph... definitely not affecting my mileage. EPA is 13.7l/100km or 17mpg.... i'm doing pretty well...
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If you have ECT on with added weight, leaving ECT on probably does work better for you.

When I was writing about WOT this was in relation to other peoples post about wanting to shift to as close to redline as possible. Which is something you do not want to do all the time. As you are close to WOT with ECT on. I mentioned in my post that if you have ECT on and don't give it WOT it will shift much sooner... it is depedant on throttle position. Go back and read it again. I don't disagree with you. With an unloaded vechile (which it sounds like you have a lot of gear / people) is what I was refering to.
 
I actually get slightly BETTER gas mileage with ECT ON in my area because it is all stop and go and a lot of up and down hill driving.

I only turn ECT off when I get on the Highway.

As for OD I have never turned it off.
 
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