R34 N/a And R34 Turbo (gtt) Transmission.. Uh, Problem.

[Kinkstaah]

Hi All.

I apologize in advance for:

a) Lack of mechanical knowledge

b) Lack of mechanical terminology

c) Lack of the ability to create a proper disclaimer-apology-list.

I own a skyline which has been off the road for almost 9 months now, at a very reputable shop in Melbourne. It was a NA+T (R34 GT Sedan) that has been decided the best course of action is to put in a GTT Engine.

However, the car is an Automatic. Apparently this causes a massive issue for my mechanic as they seem to be rather stuck with how to proceed. The car is stuck in limp mode, and due to (reasons unknown to me, and them) they are unable to get a reading from the ECU to find out why. (it is a stock ecu)

The only reasoning they can give is maybe the R34 N/A Triptronic has a different computer and setup to a R34 Turbo Triptronic Auto ECU. They are pretty much clutching at straws here when it comes to this, so I appeal to the gods of the internet to provide some insight or a link, or some documentation, or an olf wives' tale even as to the differences between the two gearboxes.

Everything else has been replaced engine wise, so effectively they are trying to get a RB25DET Neo engine working with a R34 N/A Transmission (which has been updated with a MV Auto shift kit, if that helps any). All the wiring and loom has come from the turbo engine. Nothing else from the original N/A Car is connected.

Anyone ever done this? Is it doable? WTF is going on here? Winning answer I will literally pay for a slab of beer to your most convienient location.

[666DAN]

The R34 N/A has the shift computer built into a seperate ECU in the drivers side of the car, this alone controls the gearbox, not the main ECU.

If you've put in an auto GTT ECU, it has the shift computer internal, so both shift ECU's will be sending signals to the box (confusing the fark out of it)

If you just put in the manual GTT ECU, it should all work just fine as it won't be getting the second lot of interfering signals. I ran a manual GTT ECU in my NA+t and the gearbox worked just fine.

[Kinkstaah]

The R34 N/A has the shift computer built into a seperate ECU in the drivers side of the car, this alone controls the gearbox, not the main ECU.

If you've put in an auto GTT ECU, it has the shift computer internal, so both shift ECU's will be sending signals to the box (confusing the fark out of it)

If you just put in the manual GTT ECU, it should all work just fine as it won't be getting the second lot of interfering signals. I ran a manual GTT ECU in my NA+t and the gearbox worked just fine.

I do remember reading this, but other than your comments I have found that noone (at all, anywhere) has been able to confirm this anywhere, at all. Though I do recall you writing this up in your NA+T Thread.

Is this extra ECU Disconnectable? Or should I just shell out and get a Manual GTT ECU? Will this cause problems with the box and shifting in general down the track?

Just wondering whether the best option is to get a manual ECU, or try and bypass the shifting ECU and continuing to use the standard Turbo ECU

As Nistune is a potential future option - Which is the best way to go here?

[666DAN]

Just get the manual ECU, from memory the shifting points in the n/a control unit are more favourable with regards to box life.

Alternately you could disconnect the current setup, but I'd say that would be a lot of messing around tracing wires and finding where things need to be bypassed etc etc

I've seen numerous well-priced manual ECU's in the for sale section

Edited June 24, 2010 by 666DAN

[splice]

hi i recently swap an r34 rb25de neo with automatic transmission into my 1989 nissan cederic unfortunately for me i didn't realize i need a separate transmission CPU for the transmission.I would appreciate if someone can help me find the part number for this tcm.

thanks.

splice.

[Kinkstaah]

Just get the manual ECU, from memory the shifting points in the n/a control unit are more favourable with regards to box life.

Alternately you could disconnect the current setup, but I'd say that would be a lot of messing around tracing wires and finding where things need to be bypassed etc etc

I've seen numerous well-priced manual ECU's in the for sale section

For what its worth.. this was actually tried and still isnt working with turbo OR manual ECU, with N/A Loom, Turbo auto loom, or turbo manual loom

[AZZA R34]

I may need to apologize as well my knowledge is not as vast as some, but could you use you None turbo ecu and nistune it. (assuming that it was not in limp mode befor you did the conversion).

[matturbo]

I may need to apologize as well my knowledge is not as vast as some, but could you use you None turbo ecu and nistune it. (assuming that it was not in limp mode befor you did the conversion).

Hey I got a 34 we used an mv auto s r33 valve body and black and b& m pro ratchet in the standard box as I am running a vipec which has no control out put s for gear box this setup is great

[Kinkstaah]

I may need to apologize as well my knowledge is not as vast as some, but could you use you None turbo ecu and nistune it. (assuming that it was not in limp mode befor you did the conversion).

That I don't know, I had thought about it. The problem is the workshop it is at doesn't do NISTune and there aren't many (any) workshops in Victoria that I have found that have ever, ever put a rb25det neo into a R34 N/A Auto.

Having no knowledge on it, I'd imagine the original NA loom won't work for the new engine. I'm willing to pretty much do anything at this point, the only info I've found about it in a year is posted by 666DAN who I might just pay to fly down and fix it, lol.

[GTTR34 4 door]

This may sound silly but have the solenoids been checked?

[turboedsloth]

Are the pinouts on the wiring harnesses in the same order as each other?

[Kinkstaah]

Wish I had an answer for this, the most detailed response I got was "its f**ked" and that they had stripped the car down to get access to all the wiring to no avail

..and noone else in the state wants to try their hand at it. Bit sad about it all, after spending a large amount of cashola on a shift kit and such on the box when I was under the impression that this would all work, a manual conversion to get this going pisses me off when I know that it should be 'doable' as opposed to dropping huge cash for a crap "i dunno lol /give up" solution.

[zebra]

Is the box farked? are you sure its the ecu/auto trans thats causing issues and not the swapped wiring etc for the new engine. I.e was something missed? could be something simple like the speed sensor. or coolant temp sensor cause the limp mode.

If the mechanic couldnt get consult to work it sounds like something is very wrong with the wiring,

Ive seen R32 RB26's bolted to an auto from an r34 and that worked...in an r34 GT. so 1st things 1st find out why the ecu isnt giving any signals, because I'll bet the problem starts there.

[Kinkstaah]

Is the box farked? are you sure its the ecu/auto trans thats causing issues and not the swapped wiring etc for the new engine. I.e was something missed? could be something simple like the speed sensor. or coolant temp sensor cause the limp mode.

If the mechanic couldnt get consult to work it sounds like something is very wrong with the wiring,

Ive seen R32 RB26's bolted to an auto from an r34 and that worked...in an r34 GT. so 1st things 1st find out why the ecu isnt giving any signals, because I'll bet the problem starts there.

Yep, thats what I'm going to get them (RE Customs) to do. I've also heard there's plenty of times this has happened, though noone ever has any details of the workshop that has successfully completed this. If someone has a name, and I can confirm that name so I can call them I'm happy to get the car sent there on a truck. Even if it's interstate.

I believe the issue is they couldn't get any signal from the TCM, or rather, a signal that they could interpret. Apparently its possible to bypass the seperate TCM entirely, and just set it up as you would with a normal GTT Auto, with the integrated TCM in the GTT ECU. Unfortunately there's a lot of 'apparently' and 'should' and 'I saw it once' and there seems to be no instructions on this anywhere, or at least in Victoria, lol.

The only info I have about the box being dead is, well, it wasn't dead when I was driving the car around for the whole month or so I drove it, and it wasn't dead when I drove it to the workshop. They arent even sure what combination of wiring they are even using now, given the fact they have the entire looms for GT, GTT Auto, GTT Manual and ECU's to match them all. But after a year, I doubt their enthusiasm to finish the job is sky-high.

So I live vicariously through this forum.

[zebra]

Have you tried a GTT auto, big outlay for something that might not work I know, but if you are running out of ideas....and if you have the full loom there might be worth a shot

[Galois]

Not sure if you've tried this, but maybe call people recommended on this forum in NSW as well? I've only had simple problems in comparison, but calling people recommended on here helped me out. My local mechanic was questionable though...

[Kinkstaah]

Have you tried a GTT auto, big outlay for something that might not work I know, but if you are running out of ideas....and if you have the full loom there might be worth a shot

This is potentially becoming a 'solution'. I called MV autos and they said that their shift kit should (love that term) work fine on a GTT Auto box. Like said before, apparently electrically the box is the same, so I 'shouldn't' need to actually get a GTT box to make it work.

Not sure if you've tried this, but maybe call people recommended on this forum in NSW as well? I've only had simple problems in comparison, but calling people recommended on here helped me out. My local mechanic was questionable though...

Another option is sending the car interstate, but at this point the costs are getting rather astronomical. Unfortunately not being technical it means that someone giving me instructions isn't going to work so well, I'd need something so mind numblingly step by step I'd have to pass on to someone who is handy with wiring, skylines, and this specific transmission.

Which I'm happy to call, find out, pay for, it just seems this person doesn't exist. Do not attempt, I guess, is the point here, lol.

[AZZA R34]

It sucks your having so much trouble and buy the sounds of it the shop its at doesn't want to deal with it any more. Maybe fully manualising the auto and going to a full stand alone ecu is the logical option. For somthing that should have been so simple i suprised you havn't burt it yet. good luck

[Bayside Blue R34 GTV]

Maybe you can try and put a transmission from a gtt and sell your current transmission. do you own the silver late 2000 or 2001 model r34? as i went to RE customs the other day to discuss about the na+t conversion and they told me about how a pain in the ass that silve NA+t r34 was (fixing someone elses f**k up).

Edited October 15, 2010 by Bayside Blue R34 GTV

[KiwiRS4T]

666 Dan is spot on. The RB25DE version has a seperate computer for the auto on the right of the steering wheel. The automatic transmission is exactly the same so no point in changing it. The other difference is I believe that the DET has traction control and the DE does not so that could be a problem.

You can download an R34 manual from Paul's website:

http://www.paulr33.com/

and scroll down to the problem solving sections under AT (for auto trans) - it may not mean much to you but you may get some ideas.

You say it is in limp mode so the engine goes OK? I would guess that you need an RB25DET manual ecu off a GTT.

I have suggested an alternative for you. If that is no go as a last resort I would trailer the car to MV autos if there is no auto shop in your town who wants to sort it for you!!