Reverse gear: no power....

[PatrolSlave]

Hi everyone
Just to update; its been a while.
I took her to the Diagnostics-Tuner-man this past week. He hooked her up to his computer and all was reported as normal. He re-iterated that the computer diagnoses will only show computer controlled sections. Any mechanical probs will not show. Then we took her to a suitable incline where I could demonstrate the issue while the computer was attached. No problem reported again....
As the revs, in 4-high reverse, stand and remain at 2.5, but rise quickly in low range (Ok with rockcrawler gears in the transfer case), and with the larger tires (285/75/16), he recons the engine does not generate enough torque for the tc to engage completely as that would kill the engine. ie the engine does not have time to reach closer top maximum torque when the delivery of the power is expected (the wheel on the street is against the curb). With about 10 cm of run-up the wheel gets on the curb without much hassle.
If he is right:
The good news is..... there is no problem that will leave me stranded somewhere with more damage.
The bad news is..... I still have to engage low range to reverse up a curb on an incline!
Still, the gnawing doubt and lack of faith when I sit on the "couch" behind the steering wheel dilutes my enjoyment of this machine. Until I know for sure I will remain a mistreated patrol slave.
If anyone finds something of use: please let me/ the rest of us know.
Thanks for your help so far.

[Bruin Beer]

Patrolslave,
Ek sien jy reply nou op 'n ou storie.
Jy het van tevore op die volgende gesels oor die reverse issue:
http://www.patrol4x4.co.za/viewtopic.ph ... t=no+power
Sien die link.
Sterkte.
Bruin Beer

[Peter Connan]

Patrolslave: I do not know if this is possible with the tiptronic box, but I want to request that you try going up the same curb forwards, in exactly the same way (IE stopping against the curb) but with the gearbox in second gear.

As the ratios of reverse and second are similar, that should give a similar situation?

[Bruin Beer]

Peter,
Unfortunately the tiptronic will still pull off in first.
It would have been nice to have a full manual emulation.
When selecting tiptronic second the box will only up-shift to the gear selected but will operate below the selected gear as normal auto.
I think the European versions had a snow button which I guess forced the car to launch using second gear. This might have simulated what you intended.
Bruin Beer.

[Peter Connan]

Darn

The other alternative is to find a steeper hill and use reverse in low range and go forward in high range?

[Stefaansie]

Stupid question,

Can one not program the ECU to gooi more juice and deliver the required torque?

Sorry if this was mentioned before, I didn't read all 3 pages.

[David]

I wish! But you would need a piggyback computer for the TCU - similar to an engine chip

[PatrolSlave]

Good afternoon!
I have tried Peter's suggestion (Locking in 2nd and trieng it forwards). Unfortunately it is as Bruin Beer says: the ECU realizes that more torque is needed than second gear can supply, and therefore changes down although "locked" in TripTronic. Engine revs at a leisurely 1.5 while the car easily swallows the curb in 1st.
Stefaansie's suggestion: I have no idea if that can be programmed. I am sure someone else would have posted something like that in the past. But then, it seems this "problem" is also a fairly new one considering how long the 4.8s have been around.
Thanks Bruin Beer for the link to the other discussion re "reversing up a slope". That is exactly what I experience.... at least I'm not alone!!
I think the best bet would be to take the car to a dyno tuner and have the torque and gears' performance assessed. How does one go about that with this "clever" gearbox?