Torque Converter Lock-Up Control System (1 Viewer)

[mep1811]

I had the Cruiser Brothers Torque Converter Lock-Up Control System and transmission cooler installed on my 2013 200 Series.

The lock up feature is great . Engine braking is just like having a manual transmission. Where I would have to constantly hit the brake when downshifted to slow down I do not have to do that when locked up.

With the trans cooler , the transmission runs about 10 degrees cooler than before. I did one test towing my off road trailer the converter locked up and the trans ran about 10 degrees cooler that usual.

I'm curious to see if there is any mileage improvement locked up while on the highway. I think these upgrades are well worth the money.

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[wardharris]

I had the Cruiser Brothers Torque Converter Lock-Up Control System and transmission cooler installed on my 2013 200 Series.

The lock up feature is great . Engine braking is just like having a manual transmission. Where I would have to constantly hit the brake when downshifted to slow down I do not have to do that when locked up.

With the trans cooler , the transmission runs about 10 degrees cooler than before. I did one test towing my off road trailer the converter locked up and the trans ran about 10 degrees cooler that usual.

I'm curious to see if there is any mileage improvement locked up while on the highway. I think these upgrades are well worth the money.

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No trans cooler, but the WAT TCLU Kit was good for 3-4 mpg in my GX 460 with A760F. Basically the same engine and trans as a 5.7 200 Series.

 

[mep1811]

That is great news. If I can get up to 10-12 MPG with my trailer from 7-8 I would be a happy camper.

 

[linuxgod]

That is great news. If I can get up to 10-12 MPG with my trailer from 7-8 I would be a happy camper.

I seriously doubt that will happen unless you’re spending a lot of time with the torque converter unlocked but I’m subbed to this thread now so post your results.

FWIW in my experience watching the mileage there’s about a 10% diff between locked and unlocked. So if you’re getting 7mpg when towing (like me), I wouldn’t expect you’d see more than 0.1 or 0.2 mpg difference overall since either way you’re probably locked most of the time.

City driving around town perhaps you’ll see a bit more improvement overall, assuming you’ve got unlocking up at low speed?

I assume this is just a push-button lock/auto control? What would be ideal IMO is to reprogram the ECT PWR button to force Lock-Up AND force the gear you’re in (not just limit it), so that you can put the truck in, say, 4th gear locked on a hill climb and not have the truck want to downshift to 3rd. That lack of downshifting would have more short term MPG benefit… at least in my case on the 6 speed with 4.88 gears where 5th gear locked will be 7mpg but dropping down to 4th on a slight incline is a 20+% hit

 

[mep1811]

This truck is not a daily driver . I drive it only on trips. I'll see what happens when I go on a trip in August. There will be lots of highway driving where I plan to be locked up.

 

[skrypj]

That is great news. If I can get up to 10-12 MPG with my trailer from 7-8 I would be a happy camper.

Thats not going to happen. Its only the lower gears where the TC spends a lot of time unlocked.

Also, the transmission is thermostatically controlled as far as I know, so adding more cooling is only going to change your peak temperatures, I doubled the size of the cooler on my F150 and all it did was change it from operating between 198 and 212F to operating between 198 and 210F. Same happened when I added an air cooler to my GX460 which was also thermostatically controlled. Normal operating temp was 195 and I had seen it get up to 250 once or twice towing. With the new cooler it still continued to operate at 195 normally but would only spike to 210F max.

The same will happen with the LC. Your lower bound will not change but your upper extreme should.

 

[mep1811]

Thats not going to happen. Its only the lower gears where the TC spends a lot of time unlocked.

Also, the transmission is thermostatically controlled as far as I know, so adding more cooling is only going to change your peak temperatures, I doubled the size of the cooler on my F150 and all it did was change it from operating between 198 and 212F to operating between 198 and 210F. Same happened when I added an air cooler to my GX460 which was also thermostatically controlled. Normal operating temp was 195 and I had seen it get up to 250 once or twice towing. With the new cooler it still continued to operate at 195 normally but would only spike to 210F max.

The same will happen with the LC. Your lower bound will not change but your upper extreme should.

I lock the converter up and if I'm going to on the highway for 7 hours that has to impact the mileage. Any improvement is welcome. I don't care about trans temps when I'm not towing. I got the trans cooler to keep temps down when towing.

 

[skrypj]

I lock the converter up and if I'm going to on the highway for 7 hours that has to impact the mileage. Any improvement is welcome. I don't care about trans temps when I'm not towing. I got the trans cooler to keep temps down when towing.

Yes but your TC shouldnt be unlocked all the time in the first place.

At least I know with the 8 speed in my 2018, the TC only unlocks if I am in 4th gear or lower. 5th 6th and 7th it stays locked even with my 5500 lb travel trailer. So basically its locked except for big climbs.

 

[gluaisrothai]

Yes but your TC shouldnt be unlocked all the time in the first place.

At least I know with the 8 speed in my 2018, the TC only unlocks if I am in 4th gear or lower. 5th 6th and 7th it stays locked even with my 5500 lb travel trailer. So basically its locked except for big climbs.

Can you tell from the OBD when it’s locked, or is it by feel?

 

[mep1811]

Does you truck lock up automatically? I have to push a switch to lock up and my understanding is if I stop locked up the truck will stall.

 

[TeCKis300]

I struggle with the idea of this mod and have tossed it back and forth in my mind for awhile. Watching how it behaves under tow. The trade and advantage is not as it first appears. My other car is a manual so I have a good feel for what direct drive feels like. I've also seen how the tranny heat management works when it forces lockup, and how the vehicle behaves at that point.

It's worth considering why the torque converter unlocks in the first place. If it were as simple as locking up 99% of the time for a big MPG advantage, OEMs would have jumped on that long ago. IMO, there's no free lunch.

The torque converter generally stays locked. It's not until there's a torque request from the skinny pedal, to work against grade or load, that it unlocks.

When it unlocks, the engine spins up 2-300 RPM higher. The torque converter also creates additional mechanical advantage, i.e. gearing. So instead of a straight 4th, 5th, or 6th gear, in magically creates a 4.2, 5.2, and 6.2 gear. Both of those mechanisms are advantages when working against load: higher engine RPM makes more HP available, and incrementally more gearing makes more torque at the wheels.

Without those mechanisms, the drivetrain is left to perform at a lower level or downshift. It's also useful to note, it takes fuel to make power.

So is the TCLU kit really creating efficiency or is it forcing efficiency? The trade might really be performance vs MPG. The loss of efficiency maybe only slight due to unlocking, but rather that the engine is spinning faster and trying to make more power because that's what the foot asked for.

As one that suffers from lead foot-itus a lead foot, I know I can save gas by modifying my own driving style. When towing, driving style has a huge impact. And that's where's I've landed. With OBD-II tools such as OBD Fusion, I can see lockup, and also instant MPG, HP output, fuel trims. So I modify my driving style to suit, or press on if I'm trying to make time.

 

[mep1811]

Another factor of the lock up I like is the engine braking downhill. I did a test and it was amazing. I will see how it is when I go on my long trip in August.

 

[TeCKis300]

Another factor of the lock up I like is the engine braking downhill. I did a test and it was amazing. I will see how it is when I go on my long trip in August.

Yes, very curious how this works and is a dimension I've not had experience with. Other than the torque converter always unlocks with engine braking.

 

[mep1811]

Yes, very curious how this works and is a dimension I've not had experience with. Other than the torque converter always unlocks with engine braking.

I have an aftermarket lock up system. It cannot unlock when I down shift unless I make it unlock.

 

[skrypj]

Can you tell from the OBD when it’s locked, or is it by feel?

Yes, from OBD. There is a PID in OBD fusion for it. My 8 speed absolutely never unlocks in 5th gear or higher except for a brief second after lifting off the throttle and then rolling back into it.

4the gear and lower it is never locked.

 

[mep1811]

Yes, from OBD. There is a PID in OBD fusion for it. My 8 speed absolutely never unlocks in 5th gear or higher except for a brief second after lifting off the throttle and then rolling back into it.

4the gear and lower it is never locked.

Well, you have a different vehicle than mine.

 

[kcjaz]

Well, you have a different vehicle than mine.

Works on 2013-2015 with 6 speed too:

The blue ring indicates lockup in the display that says “gear”.

 

[mep1811]

OK thanks

 

[Nothinghead]

Yes, from OBD. There is a PID in OBD fusion for it. My 8 speed absolutely never unlocks in 5th gear or higher except for a brief second after lifting off the throttle and then rolling back into it.

4the gear and lower it is never locked.

Weird. I occasionally get lock up in 4th when towing and a lot of unlocked 5th and 6th. When I rarely choose 7 or 8 when towing, I also see it unlocked when coasting downhill and maybe half the time under any load (this is hard to say since it downshifts with the slightest pedal pressure.

 

[TeCKis300]

Weird. I occasionally get lock up in 4th when towing and a lot of unlocked 5th and 6th. When I rarely choose 7 or 8 when towing, I also see it unlocked when coasting downhill and maybe half the time under any load (this is hard to say since it downshifts with the slightest pedal pressure.

IIRC you have pretty large tires on your cruiser?

This may very well be one of the consequences of large tires. The vehicle ECU doesn't understand the tires, and sees it as additional load. When combining tire load with towing loads, the increased of both is such that it's not allowing the transmission to get into lockup.

As we still don't have proven ways to retune the transmission ECU, though we might be close - @skrypj ...

Perhaps this lockup ECU might be a fix? The other known way to resolve this at the moment is to re-gear. The 8-speed guys will want a 3.9 form the pre-2016 cruisers.

With corrected gearing on mine, I can see it readily lockup in all upper gears once I'm in cruise and the load is low enough. Normal to see it unlock on coast or engine braking.