Torque converter lockout

[Geof]

New NX, 1 month old, 1500 km inspection booked for next week. Last weekend was the first chance to do a >200k highway trip. I understand that the auto has a lockout for the torque convertor - does anyone know what speed or otherwise that it operates? Reason for asking - at steady 100 km/h on the flat - the slightest increase in accelerator pressure (for a slight uphill stretch) causes the revs to increase noticeably, reverting to previous reading when the road levels out. If the TC is locked out, how can this happen? Same when using cruise control. Same when transmission is in manual mode (5th gear) so it can't downshift.
Could it be that lockout is releasing too easily? It is rather annoying when on cruise control to have the engine noise change every time there is a slight rise in the road.
Previous vehicle 2001 Prado - lockup activated over 80 km/h and stayed until speed went back below 80.

[spot01]

Unsure about any converter "lock out"? The converter has a lock up feature which sounds like it is working normally on your car.

In manual mode, the box can change down but not up, but that is not what is happening here.

In my MY16 NX, the converter locks up at a true 90kph (per my GPS - about 96 on the speedo) and will unlock (regardless of auto mode or manual) on an incline or if you put your foot down a bit - it increases the revs by a couple of hundred & feels like a gear change, but isn't (still in 5th). Assuming you have a MY17 NX with the slightly taller gearing & different engine tune (a few kw less power & DPF), I wouldn't be surprised if the lock up is nearer 100 on the speedo (the price we pay for cleaner emissions).

I've had several Pajeros, & they have all behaved like this, so your car is normal IMO.

Difficult to compare to a Prado from 16 years ago - different car, technology & emission regulations, etc.

At least the Paj doesn't have 8 or 10 gears in the auto like some - they must be changing gears all the time!

Enjoy the Paj - it will serve you well.

[old Jack]

Geof,

Have a look at this,

https://www.mm4x4.com.au

This was specifically designed by a forum member for Gen 4 Pajero and he has been testing it on his NX with great results.

OJ.

[Stevenf]

Yep torque converter unlocking at low throttle settings at ~2000 rpm is the only thing i hate about the pajero.

The pajero always goes to 5th then unlocks. Some times going back to 4th allows the converter to lock up and lower the engine rpm.

When towing u have to use manual 3rd up to 80kmh and then stay in 4th to keep torque converter locked up.

Thought about a lock up kit. Then did some google research. Found https://www.schaeffler.com/remotemed..._symposium.pdf

The 3.2l 4 cylinder engine causes major tosional vibrations at low engine speeds and high torque. Torque converter unlocking stops the torsional vibrations.

U can sometimes feel a engine roughness at 2000 rpm just before torque converter unlocks. Heard some people with torque converter lock up kits say engine feels very harsh and not to lock up at low speed.

Im now use to it and does not bother me. Pajero engines seem to do fine at 3000rpm in 4th when towing.

I would not get a lockup kit. Suspect they could cause damage if used incorectly.

[NTBenny]

Interesting post Stevenf. I've been doing quite a bit of research on TC lock up and speaking with a few people about torque converters and why factories don't lock up the TC earlier and why so many people have to fit after market lock up kits. As your post explains and others have said to me it seems that manufacturers are attempting to reduce NVH by unlocking the converter. What I've also been told is lock up clutches are not designed to cope with large torque inputs and they should not be used up inclines or when using more than 80% throttle. Lock up is really intended to improve fuel economy at light throttle by reducing lost energy through the fluid coupling. The other benefit to that of course is less heat production.

Benny.

[old Jack]

Interesting post Stevenf. I've been doing quite a bit of research on TC lock up and speaking with a few people about torque converters and why factories don't lock up the TC earlier and why so many people have to fit after market lock up kits. As your post explains and others have said to me it seems that manufacturers are attempting to reduce NVH by unlocking the converter. What I've also been told is lock up clutches are not designed to cope with large torque inputs and they should not be used up inclines or when using more than 80% throttle. Lock up is really intended to improve fuel economy at light throttle by reducing lost energy through the fluid coupling. The other benefit to that of course is less heat production.

Benny.

Best lockup kit on the market has been developed by a forum member, technically it is light years ahead of all other lockup kits currently available.

https://www.mm4x4.com.au/

OJ.

[nj swb]

What I've also been told is lock up clutches are not designed to cope with large torque inputs and they should not be used up inclines or when using more than 80% throttle.

I had also been told that, so when I started developing my lock-up I did some testing to determine what load / throttle percentage the factory unlocked.

Climbing the South East freeway out of Adelaide, in 4th gear at 90km/h, the factory programming keeps the torque converter locked at 100% throttle. At peak engine torque, with full throttle on a sustained climb, Mitsubishi don't unlock the torque converter.

Some time after that, OJ posted some graphs from Mitsubishi that showed the same thing - above a certain rpm, the converter stays locked regardless.

[Stevenf]

Yep at 3000rpm full throttle torque converter is locked.

Peak torque is not a problem for the lockup.

But at low rpm around 2000 rpm there is a harmonic that causes a vibration above a certain throttle setting. Unlocking removes this vibration.

How does the pajero feel when you do a lockup override at full throttle from 1700 to 2500 rpm? Does it feel rough? Does this cause damage to the transmission or engine mounts?

[nj swb]

How does the pajero feel when you do a lockup override at full throttle from 1700 to 2500 rpm? Does it feel rough? Does this cause damage to the transmission or engine mounts?

Personally, full throttle locked feels fine to me from about 1800 rpm up. Below that, the amount of vibration depends on the amount of throttle. About 1400 rpm seems to be the lower limit for using the lock-up with light throttle - but it the conditions are that "light" I generally don't bother locking anyway.

If I want to accelerate hard but the revs are too low, I change down a gear or two - whether the converter is locked or not.

[m_and_m]

Best lockup kit on the market has been developed by a forum member, technically it is light years ahead of all other lockup kits currently available.

https://www.mm4x4.com.au/

OJ.

Thanks OJ - I've had a lot of interest in the kit, and also for the challenger too - so will be in touch in the new year to join forces and modify it to make the challenger perform how it should have from factory

Anyway, probably time for me to chip in on this discussion.

NJ is correct that under normal circumstances you don't need the torque converter to lockup and having it slip provides a nicer, and smoother experience (lower NHV)
The lockup clutch is also more than capable of handling full throttle an high torque. If you want to test this yourself, do a 3rd gear full throttle acceleration and you'll feel the TC lockup at about 80kph. Feels like a 'mini' gear change.

Above 2000-2300rpm under full throttle there's no difference in the NVH.

Between 1500 and 2000 though you'll certainly get slight shuddering (higher NVH) if there's too much torque - which to an typical customer is undesirable - hence why it unlocks.

My kit is optimise to allow you to lockup at below 2000 rpm and automatically unlock just prior to experiencing this unacceptable NVH - but in practice I'll change down to 3rd to ensure it stays locked up. My lockup point changes according to the load on the engine, fully automatically.

This means, for example, you can lockup in 4th at 60kph under really light throttle, but as soon as you apply say medium throttle it unlocks immediately. At higher speeds in the same conditions it's more tolerant and stays locked up.

After much investigation myself, I believe the reasons the factory will unlock the torque converter is not due to excessive load (or weaknesses), rather for a nicer and smoother feeling auto. The compromise is higher transmission temps, and lightly fuel usage.

So the transmission is optimised for smoothness at the expense of higher transmission temps, which under normal conditions are not a problem. It''s only when you start working the car hard (like towing or long steep inclines) in summer that the benefits of the lockup kits shine through.

Today was about 30deg in Adelaide and after 30 mins under city driving condition my temps hit 105 deg without the lockup kit active. Whilst pretty hot, this is still within limits. So you can imagine how easily you can get unacceptable temps with a load on the back! Anything over 125deg should be avoided.

If you want to keep up to date on my lockup kit's progress (and others in the pipeline) you can visit my site https://www.mm4x4.com.au/ and subscribe with your email address.

[Geof]

What do you recommend for reading the transmission temperature? I have the EDS from 4WDSupacentre which reads some engine data but nothing about the transmission.

[Pajshomoneroguntero]

What do you recommend for reading the transmission temperature? I have the EDS from 4WDSupacentre which reads some engine data but nothing about the transmission.

An app called Torque Pro (you'll need the Pro version) circa $5 for your Android phone/tablet and a Bluetooth dongle to send the ECU info to your phone (plugs into the OBD2 port by the driver's left knee).
It's also available for Apple devices however you'll need a WiFi dongle instead.

There is a small mod to program for the Torque Pro to read the trans temp. Details are within a thread I'll need to find the link for...standby.

[Dicko1]

What do you recommend for reading the transmission temperature? I have the EDS from 4WDSupacentre which reads some engine data but nothing about the transmission.

Many of us use an Ultragauge. A good value small screened device that is completely programmable to customise what ever data readings you want displayed. Mounted on dashboard on drivers side , it also has built in prgrammable alarms, reads codes and an clear codes. Plug in to OBD skt set it up and forget. Search on here for more info. Purchased in USA.

[m_and_m]

Many of us use an Ultragauge. A good value small screened device that is completely programmable to customise what ever data readings you want displayed. Mounted on dashboard on drivers side , it also has built in prgrammable alarms, reads codes and an clear codes. Plug in to OBD skt set it up and forget. Search on here for more info. Purchased in USA.

I use the ultragauge also. Very happy with it. Regardless of which product you choose though it must have the ability to read a custom entered CAN messages. The transmission temp is not in the OBD2 standard, and the gauge needs to be programmed to pick off the Mitsi proprietary message from the Canbus.

[Pwoffey]

I use the Scangauge II, as do quite a few others on the Forum. It's pretty comparable to the Ultragauge, and codes are available for the auto trans temperature from several threads on the Forum. Scangauge has an Australian distributor and support (Ample Outdoors).