I "fixed" my poor fuel economy

[IBallEngineer]

A while back I read through clownmeats thread and he said that while looking at the wiring for the automatic transmission he found that he could lock up the torque convertor electronically. Is that even possible? I was under the assumption that the torque convertor locked up by itself at a certain rpm if there wasnt too much torque going through it. id love to be able to lock the torque convertor around town, with my tires and gearing it wont lock until i get up to about 51 mph.

Yup, you can lock it by grounding the wire that would be grounded by the ECU, on the 02 diagram that would by connector E9 terminal 1. I played around with this circuit in a GM 7004R I had in my 51 Chevy. I made it lock up in 3rd, but that required 12V switching and I never made it something permanent. Let me tell you, locking up in 2nd made that thing a dog! haha.

 

[D Farms]

Yup, you can lock it by grounding the wire that would be grounded by the ECU, on the 02 diagram that would by connector E9 terminal 1. I played around with this circuit in a GM 7004R I had in my 51 Chevy. I made it lock up in 3rd, but that required 12V switching and I never made it something permanent. Let me tell you, locking up in 2nd made that thing a dog! haha.

Thats pretty cool, but what happens if it tries to change gears when its locked up. i would want to have it stay in 4th gear while its locked and then have it unlock for any gear change.

 

[WallyWest]

Thats pretty cool, but what happens if it tries to change gears when its locked up. i would want to have it stay in 4th gear while its locked and then have it unlock for any gear change.

Some drag racers with automatic transmissions install a switch to lock up the torque converter. Exactly how it works depends on how the lockup is engaged, but usually it's a simple circuit that when open locks the converter.

So if you wire a switch into it and leave the switch closed the car acts like it always did. If you flip the switch the torque converter locks regardless of gear. (Might be vice versa on the open/closed part, but that's the idea).

I don't know if this is true for all cars, but I had a friend with a lock switch and he said he would flip the switch just after launching and leave it that way through the run. However if he didn't switch it back when decelerating the transmission wouldn't downshift.

It would in theory give you a bit better gas mileage if you locked the converter shortly after hitting the gas from a stop. You would probably have to accelerate a bit harder than normal, and/or use the ECT button, to keep the shift points high enough so you didn't bog down when hitting the next gear. And possibly it would lock you into 4th gear when you got there. Kinda doubt it would be worth the hassle.

 

[IBallEngineer]

Thats pretty cool, but what happens if it tries to change gears when its locked up. i would want to have it stay in 4th gear while its locked and then have it unlock for any gear change.

Well now you want sophistication! You'd need some sort of logic circuit to do that. In reality you would want the converter to unlock if you had to accelerate even in the same gear, because without the stall of the converter, you'd have some serious lag.

I bet you could do some relays that would only ground if you were in 4th gear, so if you shifted it would turn off, and even a throttle switch to turn it off. But that would be clumsy at best, and the ECU already does some of that, just not to your taste.

 

[D Farms]

does the torque convertor not act like a clutch in a manual transmission?

 

[Slowgoat]

you do know why the odometer is off right? its because you increased your tire size, and there is nothing you can do short of getting new abs rings with more teeth machined that will correct it. mine is off 25% because mine came with the 28" tires and now im running 35s.

Speedohealer

Here's a thread:

http://www.toyota-4runner.org/4th-gen-t4rs/51210-speedohealer.html

 

[jgigmj]

you do know why the odometer is off right?

 

[WallyWest]

does the torque convertor not act like a clutch in a manual transmission?

Kind of.

It's a fluid coupling that allows the engine to be permanently mated to the transmission. At idle the input of the torque converter spins, while the output doesn't, even though there is still a connection between the two. It does this through some nifty fluid dynamics that you can google if you're interested. Bottom line at this point it acts like an extremely tall gear with some slippage allowed. When you start to accelerate for a split second the engine rpms rise quickly while the transmission is only spun a little bit. Then the torque converter hits it's stall speed, which is where it simulates a clutch drop. Again, nifty fluid dynamics come into play and the torque converter "shifts" down to nearly a 1:1 coupling. Not quite, but close. Then at cruising speed lockup is engaged and there is a real, mechanical link made that takes the torque converter out of the equation.

 

[D Farms]

Kind of.

It's a fluid coupling that allows the engine to be permanently mated to the transmission. At idle the input of the torque converter spins, while the output doesn't, even though there is still a connection between the two. It does this through some nifty fluid dynamics that you can google if you're interested. Bottom line at this point it acts like an extremely tall gear with some slippage allowed. When you start to accelerate for a split second the engine rpms rise quickly while the transmission is only spun a little bit. Then the torque converter hits it's stall speed, which is where it simulates a clutch drop. Again, nifty fluid dynamics come into play and the torque converter "shifts" down to nearly a 1:1 coupling. Not quite, but close. Then at cruising speed lockup is engaged and there is a real, mechanical link made that takes the torque converter out of the equation.

right so it acts just like a clutch, meaning that it needs to be unlocked in order to shift, otherwise you will grind gears. im just spitballing here but if you forced it to stay locked in 4th while forcing the torque converter to be locked there would be no chance of damage. if this was all on a switch you could engage the switch when you get to cruising speed and then have good gas mileage below the normal locking point. if you didn't unlock it and came to a stop it would stall, just like a manual. [MENTION=75824]Clownmeat[/MENTION] any input on this?

 

[IBallEngineer]

right so it acts just like a clutch, meaning that it needs to be unlocked in order to shift, otherwise you will grind gears. im just spitballing here but if you forced it to stay locked in 4th while forcing the torque converter to be locked there would be no chance of damage. if this was all on a switch you could engage the switch when you get to cruising speed and then have good gas mileage below the normal locking point. if you didn't unlock it and came to a stop it would stall, just like a manual. [MENTION=75824]Clownmeat[/MENTION] any input on this?

You are sort of on track, but not completely. Still, that doesn't matter. Locking the converter is only viable at a steady cruising speed, you need the converter to give you torque multiplication of the "slippage" to accelerate, and of course you need the coupling to take place at higher than idle speed. Locking the converter won't affect shifting, the transmission does the "slipping" with it's own clutches. But with the converter locked, you would have a hard time getting to upshift speed anyway. Well not a hard time, but if you want to move quickly you need to rev up a little and the TCC makes that slow. You could make a lock out so it would only lock in 4th, or both 3rd and 4th, but you'd still have to manually turn it off for normal driving. You wouldn't want it to automatically lock as soon as you it a gear. Also it is a very small clutch, you wouldn't want to subject it to heavy loads, not designed for that. That's why it automatically unlocks when you stomp the pedal.

 

[4RunnerFlip]

I have a 97, can confirm.

I also have a 97.. and i can also confirm

 

[Bad Luck]

I also have a 97.. and i can also confirm

We’ve all been waiting almost 7 years for more confirmation. Thank you. I can sleep better at night now.