Auto and torque converter issues

Any of you guys found solutions for the auto box? The issue being the torque convertor does not lock up until 3000rpm - hence the hunting on, slurred shifts and lack of engine breaking.

This mob in melb. seem to have addressed the issue.

Any thoughts on this solution?

Wholesale Automatic Transmissions

Wholesale Automatic Transmissions

They seem to be addressing a problem that I just haven't experienced. Admittedly, I'm only towing up to 2T and not 3T, but 30,000km of towing in not quite 2 years of owning it hasn't revealed any major issues with the auto box.

I wonder if the choice of oil has anything to do with it? Nissan are extremely specific on the grade of oil used in the gearbox - so specific, in fact, that using anything OTHER than the oil they want you to use voids the warranty on the gearbox (for certain failures). From the manual, page 13/50 of MA.PDF:

*5: Using automatic transmission fluid other than Genuine NISSAN ATF Matic Fluid J will cause deterioration in driveability
and automatic transmission durability, and may damage the automatic transmission, which is not covered by the warranty.

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That's not to say those guys haven't produced something really worthwhile. When my warranty is gone and my 120,000km of capped-price servicing is over AND my torque converter starts giving me grief, I've now got a place to go looking at.

As for the engine braking, mine does it but it's mild to say the least. I have been thinking about fitting an exhaust brake (jake brakes are controversial at best, illegal at worst) but I'm not sure what the added compression will do to the exhaust manifold and turbocharger. I need to learn more about this - having a heavy duty engine brake will be valuable, especially when hauling the 'van down a long steep hill like Mt Ousley, Mt Victoria, Bulli Pass, Alpine Way etc.

I am not sure that I have experienced any "problems" either but I would dearly love to be able to lock the thing in overdrive when towing, the choice being mine as to when it comes out.

With something heavy on the back, I find it quite tiring trying be ever so gentle with the pedal so as to keep it in overdrive. It generally won't mainatain a reasonable speed in overdrive unless condition are perfect & all of the stars are aligned.

I am really not one for modifications but would seriously consider a chip if it would solve the issue.

Oops, maybe I strayed off topic, but that would be my only criticism with the vehicle I think?

Joe, mine doesn't slip out of overdrive as much as it unlocks the torque converter. I had considered trying to hack the TCM so that you could flick a switch on the dash that kept the TCC (Torque Converter Clutch - the locking mechanism) in a locked state but considered it to be a little too dangerous.

It WOULD be nice if, once the TCC locked, you could put your foot down a little harder than we are able to at the moment. However, I was watching the ECU's reported "Engine Load" figure while driving along with the van behind and it wouldn't unlock until the load figure passed 70%-ish. I don't know if that figure can be adjusted to 85-90% so you could give the thing a bit more of a squeeze to maintain speed.

I do know that when the engine load is 80% or higher, the engine temps rise dramatically. In order to be successful, you'd have to (in order):

1) Improve the cooling system to a significant degree
2) Probably chip the motor so you could HAVE extra power
3) Make the TCC changes

There might be some advantage, if you could get enough hp & torque out of it, in changing the diff ratios. You'd then force the TCC to lock at 1300rpm instead of the current 1600rpm, and have the thing cruise (100km/h) at about 1700rpm instead of the current 2,000rpm.

I suppose you could buy a 550, which already does that, but if the changes to achieve the above weren't too expensive, it's somewhat appealing.

I really do apologise for hijacking this thread but for me to sit comfortably in the 90's, the box is usually in 4th & sitting roughly around the 3000rpm mark. As soon as it kick back into 4th, the wife has started making slurping sounds, imitating the amount of juice it is sucking?

I think a load of 2500kg plus is too much it unless you have deep pockets or an oil refinery

I was hoping a chip might give it a bit more torque to mainatin a reasonable speed in overdrive.

I wouldn't sweat about hijacking the thread, it's all about what you're talking about.

At those RPM the fuel rail pressure is definitely higher. The ECU even knows it's gobbling more fuel, which is why I try to get into overdrive as much as possible. At Christmas on the fuel we picked up @ Kings Creek Station I was amazed to get mid-15s. There was one key difference - we were NOT in any sort of rush at all - so ambling up to speed (and I mean a long, drawn-out wind-up not a rush to 90km/h then backing off) was the order of the day.

I'll try to get some actual figures of fuel rail pressures and ECU-reported LPHK. Ideally, I want to record the following:

1) Vehicle speed
2) Engine RPM
3) Throttle position
4) Engine load
5) Fuel rail pressure
6) LPHK
7) MAF rate
8) Boost pressure

I might write to Ian Hawkins (developer of the superb Torque application that I'm using) and see if something like this could be done.

joe2006 i was on the phone to wholesale automatic today about the auto and towing my caravan 2500kg and 3.2m h. So im going full make over in the box a new converter and nomad body .Now the TC locks in at 1500rpm and when you put your foot down it doesnt slip so you dont have to drive like and old man. He said the D40 are saving 5-10% fuel with the new box and when your towing the van it will be like a new truck .

D40 AUTO said:

joe2006 i was on the phone to wholesale automatic today about the auto and towing my caravan 2500kg and 3.2m h. So im going full make over in the box a new converter and nomad body .Now the TC locks in at 1500rpm and when you put your foot down it doesnt slip so you dont have to drive like and old man. He said the D40 are saving 5-10% fuel with the new box and when your towing the van it will be like a new truck .

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Thanks for the info.

When do you plan to have the modifications done?

Please keep us informed how you go.

not getting it dun till xmas need the truck for work and its about $3000

Very interesting, my nav holds o/d much better whilst towing since I had the Chip installed and have more torque , some of the shifts fell a bit doughy especially the 1-2 with the van on the back and I have the shudder issue, which again was improved with the chip surprisingly. However this new converter sounds promising for future reference, I think I'll take the "it aint broke so i won't fix it" route at the moment though.. But I'll be very interested in the outcome D40 auto..

Rich, if yours is shuddering around the 80-90km/h mark (which is normally accompanied by a drop of about 500rpm) then your torque converter clutch might have an issue that Nissan have been replacing under warranty (faulty torque converter clutch/valve). The TCC is responsible for the solid engagement between the output of the motor and the input to the gearbox. Faulty ones don't engage cleanly and cause a shudder.

Interestingly, that wholesale auto transmission place also has a Torque Converter Lockup Manual Control Kit although it doesn't appear they've done one for the D40 yet. This device would seem to be able to do a couple of very interesting things, how's this list grab you:

* Will keep the TC locked all the way down to vehicle stopped and will stall the engine
* Will allow much more effective engine braking
* Will allow full throttle to be used in any gear (eg overdrive)

I'd also imagine that you could now "clutch start" the Navara by rolling it with the gear selector in '1' then flicking the switch.

I might want one of these.

I made a manual torque converter lock-up circuit for my previous vehicle (a 2003 Patrol with the dreaded 'hand grenade' engine) and can vouch for their effectiveness. When towing my van I was sitting in 4th gear at 2,100 RPM and the transmission temp was 150 Deg C (converter unlocked).
I used to change back to 3rd gear (1:1 gearbox drive ratio) and then I locked the converter, the rev's went to 2,500 for the same speed as before but the transmission temp came down to 85 Deg C. (Note: the slipping torque converter made lots of heat, to make heat you need energy and that came from extra fuel). So driving at third with the torque converter locked up, I actually saved fuel even though the engine was reving more.
For Old.Tony - Sorry but you can't 'clutch start' the vehicle as the hydraulic fluid pump is directly connected to the input shaft of the gearbox and turns only when the engine turns. Towing the vehicle may turn some of the internal gears, however the internal clutch packs will not get any hydraulic fluid under pressure so they may not have the clamping force required to turn their respective drive gears. (That's why you can't tow an auto and doing so may burn out the clutch packs real quick). In addition, the stator/rotor combination 'power input' will be reversed and will not transfer the amount of energy required to turn the engine over. Sorry to rain on you parade.

I digress.

Benefits of a lock-up - less fuel, less heat and less wear and tear on the torque converter.

I have been toying with the idea of making one for my D40 and if I can hide it from Mr Nissan (warranty conditions) I will try. The problem is with these new computer controlled
vehicles is if the computer detects an abnormality, it places the car in a a 'limp home' mode and this may happen if the torque converter is locked when it should'nt be. (Testing required).
If anyone can advise what the wire code is (and where to find it)
that controls the solenoid for the lock-up clutch, I would be very greatful.

Regards to all.

Foxy

Not worried about rain, have mastered the umbrella skill many years ago. If it doesn't work, then it doesn't work. I know in the manual it says I'm allowed to flat-tow my vehicle for a small distance (a few km) at no more than 55km/h (I think) and then have to stop. At that rate, I ought to be able to start the car numerous times - but if it ain't gonna work, it's no big deal. The better bonuses were the engine braking and the removal of the unlocking.

As for the wires, the TCM happens to lie inside the sump of the automatic transmission in the D40 and that's where the decision about locking/unlocking is made. Reading between the lines in the manual would indicate that there's not a function available to command the TCM do lock up anyway - so you'd have to replace the TCM. That auto transmission place does sell a whole new TCM and valve assembly for the D40 - perhaps they could advise further.

I haven't examined the connections from the ECU to the transmission. It's possible there's a means of forcing it externally. If you're experienced with that sort of thing, grab a manual and have a good read. Unfortunately it's not the easiest thing to work through.

Hey Old.Tony
That's a bugger.
The TCM for the patrol was in the LHS kick panel in the front of the cabin and was easy to trick. The problem I see with the D40 is the amount of 'tricking' required due to the amount of sensors in the transmission system. I must admit, I pressed for time these days to sit down and work these thing out (family commitments) so I think the best bet would be the transmission upgrade through Wholesale Auto Transmissions (I have dealt with them before and they are very good people to deal with and they certainly know their shit).

I'll have a quick look in the manual and if I work anything out I'll be sure to let everyone know.

Foxy

That's probably why Nissan moved it to where it is!

D40 AUTO said:

joe2006 i was on the phone to wholesale automatic today about the auto and towing my caravan 2500kg and 3.2m h. So im going full make over in the box a new converter and nomad body .Now the TC locks in at 1500rpm and when you put your foot down it doesnt slip so you dont have to drive like and old man. He said the D40 are saving 5-10% fuel with the new box and when your towing the van it will be like a new truck .

Click to expand...

Revising an old thread did you ever get this work done and if so what was the result.