Ns auto ECU question.

[dwright74]

from what I understand, the torque converter acts like a hydrualic clutch, preventing stalling when the transmissions is spinning slower then the engine. When going up hill it's benefical as it allows power to be transferred smoothly and without stalling, going down hill it acts similary to depressing the clutch on a manual, but not as dramatic. By locking the torque converter, the engine and transmission are directly linked, so going down hill you get maximum engine braking.
I'm sure someone else can explain it better, but it's what I understand.

[studog]

Torque Convertor Operation

Hi Guys
A Torque Convertor is effectively a Fluid Coupling, 1 set of vanes driven by the engine forces ATF against another set of vanes that drive the input shaft. In a torque convertor there is a stator in between the two that locks in 1 direction and directs oil from the drive vanes into the driven vanes and assits in turning the driven vanes, this is what multiples the Torque produced by the engine as transfered to the transmission input shaft (similar to riding the clutch in a manual.) The size of the TC and the angle of the vanes determine the stall speed of the unit, this being the max rpm under FULL LOAD.
This is a major benefit when towing or steep hill climbing in rough conditions, but is a disadvantage in hill decent due to lack of engine braking due to TC slip at closed throttle.
Modern cars have a clutch that locks the two halfs together that the manufacturer uses for fuel economy purposes by partially applying the clutch via a duty cycle to modulating solenoid, meaning when applied the clutch is rarely operating at 100% pressure.
We apply 100% pressure with an external switch giving total control of lock-up operation at all times in all forward gears, this allows 100% engine braking capability during decent and lock-up control when cruising.
In some cases 1st gear lock-up is not availablle without the Valve body being modified due to the OEM hydraulic design.
The other major advantage is that the lock-up can be used to control temperature , the TC creates enormous heat when unlocked and under load and you can alter driving style if the temp is monitored and by locking up the convertor heat generation ceases and you will see the temp drop on a gauge immediately with the lock-up applied.
Hope this is of assistance
Stuart Kitto
Wholesale Automatics

[dwright74]

See I told you someone else could explain it better.

[Ian Sharpe]

I was told it w as only for towing & low range downhill not for general driving on HW, also you have to turn it off when you pull up as it will stall the vehicle. To me this would just be a PIA & if you are worried about downhill gearing in low then get the reduction gears

[dwright74]

I've got reduction gears and love them, but I find that 1st is too low for anything but the steepest decents and second is generally still a little fast. If this switch can bridge the gap between first and second, then I think it will be a good investment.

[pauld]

I happily use on the highway towing or not. Also useful for engine breaking on mountain roads. You certainly wouldn't use around town. If you forget you get a few seconds of vibration as you pull up and I have found that is enough time to flick it off, a steering wheel paddle would be nice

[oldmate]

Sorted !

OK so I got the home made switch sorted last night.
Drove to work this AM no problems - about 60Kms, no codes no warning lights.
Definitely makes a difference to drive. As mentioned by others it gives a "manual" feel on acceleration and engine braking.
I only tried it on the highway at about 80 and 100 K's - not a great deal of difference at 100 odd, but a definite difference at 80.
You can feel that you are on the limit of the engine torque at 80 in 5th without the extra revs from the TC, but just give it a tiny little boot and it drops to 4th and feels very responsive.
Will be very interesting to feel how it goes when I get my Chip It, will order one this week. Will also be very interesting next time I tow the van.

[4ePikanini]

so the auto still changes up and down with the torque converter locked?

Is it jerky?

[Pickle]

so the auto still changes up and down with the torque converter locked?

Is it jerky?

Nah !
Dave

[oldmate]

Nah !
Dave

As Dave said it isn't jerky.
A little firmer shift though I would say.

[oldmate]

OK so I got the home made switch sorted last night.

Just need to fiddle with the resistor value now - the one I'm using (2.8 ohms) is getting a bit hot, might need to try something a bit bigger to limit that current draw

[Gulfstream]

Here's my switch installed:

[drew4x4]

Hi all,
Has anyone got some advice on the correct value resistor to use and possibly wiring diagram? Feel free to PM me if prefer.
Cheers,
Drew

[4ePikanini]

I made my own kit after scouring through the wiring diagrams and manuals.

I have gone one better though......I think......

I have been feeling uneasy about that resistor generating a fair amount of heat when the ecu allows 12volt through it. Essentially the ecu acts as ground so if it normally would lock up 12volt will pass through the resistor.

To combat that i have added another relay that will bypass my wiring and render the gearbox in stock form when the ecu wants to use lockup. So essentially when my switch is on and the ecu wants lockup it locks through it's own process but as soon as it unlocks my relays kick in and keeps it locked up.

With the switch off the gearbox wiring is essentially stock.

So the resisitor essentially will never see 12volt but for the split second in relays switching power around. In this method i dont know if the relay is crucial but im leaving it there to avoid the ecu maybe throwing a code.

Taking another test drive today i can clearly see how the slippage in the box wastes fuel. This mod will definitely save me on fuel economy. I will almost put a wager on it.