Jump to content
SAU Community

Recommended Posts

Hey guys new here but at my witts end with my car and really looking for some help.

 

 

 

 

 

 

 

Time for a long story. Owned my r34 NA Auto for about 9 years now. Car was running well until about 4 years ago when I started to get the A/T limp mode whenever the car went to shift into 3rd gear. Wasn't to fussed at the time as the car was about to go into the shop for a full motor and gearbox build.

Car ended up with a full forged motor with turbo and all the bells and whistles which I haven't had a problem with. Gearbox was also completely rebuilt from front to back and absolutely everything is brand new. Car is running a haltech 2500 elite if that helps. 

Now to the pain. After all the money and things replaced it still has the same AT problem when it tries to shift to 3rd and it just sticks on 3rd gear limp mode from there on out. 

Car has always been and is still auto. It has the original box and motor in the car and me and my mechanic can not figure out why the hell it keeps happening. 

My next move is replacing the TCU module as it's separate in the GT model but other than that I'm lost

Any ideas or help would be much appreciated 

Picture just coz I like to show it off.

Thank you guys

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

20230123_152025.jpg

Link to comment
https://www.sau.com.au/forums/topic/484399-r34-det-gearbox-problems/
Share on other sites

This is a normal and expected outcome from doing what you have done.

I'm tired of going over what is going to be needed to fix it. The best solution is to not fix it, and to put a manual in.

Can't drive manual? Learn.

This is both the best solution and the simplest solution.

The more complicated solution is to reconnect the OEM ECU (yes, ecu) and reconnect its relevant parts to the TCU. Then you effectively splice the Haltech into the engine-parts of the OEM ECU, and run the haltech like an old school piggyback.

But it's a NA gearbox which will not last at all. It won't last if you put a shift kit in. It just won't last, period, so doing all of the above work will cost you thousands and leave you very sad.

Still don't want to go manual? You could go a Turbo gearbox and build that, but it's still a $10K adventure to get it close to being able to perform the way you want, including an aftermarket gearbox ECU, which gets wired in similar to the TCU's original setup. You will need aftermarket flex plates (they do not exist) and other bespoke things.

Your other option is to fully manualize the transmission.

The crux of the issue is that the R34 Turbo ECU has the gearbox/TCU pins on the engine ecu. The NA has them spaced out to a seperate TCU with the same inputs/outputs for Nissan reasons. It is plausible to rewirewire wires that lead to the NA TCM pins into their corresponding R34 GTT ENGINE ecu pins. This _will_ work, and then you could feasibly run a Nistune Engine ECU, which also only works for the Turbo/GTT ecu. The workshop manual pinouts are a treasure.

In theory you could look ingo the workshop manual and see what inputs the R34 TCM actually needs so it can operate the gearbox. It probably has wiring for power, tach, TPS and such from the engine ECU. Probably. I never looked into this.

Lots of ECU wiring and f**king about ahead for you. All of it more expensive than a manual swap. Much more complex than a manual swap. Much worse result than a manual swap. My car spent years at a workshop with them trying to figure this out until I did it with a mate in about 30 minutes by actually reading the manual.

Oh look I said manual again.
Go manual.

Any excuse you have about this is invalid. Refer to this post in the future, so you can re-read it and be like "lol shit yeah he was right I'm glad I went manual"

  • Like 2

I understand the whole going manual thing but I had a work accident a couple years back where I lost alot of feeling in my left leg so I am unable to feel things like clutch pressure so unfortunately manual is not an option for me.

 

 

 

 

 

 

 

 

  • Like 1
24 minutes ago, theonlypancakeofdoom said:

I understand the whole going manual thing but I had a work accident a couple years back where I lost alot of feeling in my left leg so I am unable to feel things like clutch pressure so unfortunately manual is not an option for me.

 

Then you're in for a rough spot.

I would legitimately consider the crazy path of a BMW DCT conversion. Anything else is going to be underwhelming. Sensible me says buy a car with a decent auto in it. A V8 10 speed mustang is going to be a lot more fun and a lot more fast, and a lot more everything than the anguish of going down this path.

It really depends on how irrationally compulsive you are with regards to keeping a R34, or whether you want what an R34 can do. If in your mind this is a 100K, once in a lifetime car, BMW DCT is your answer. If logic is being applied in any way, shape, or form... A10 Mustang or one of the many other automatic-optioned vehicles is going to be far faster, simpler, easier, more enjoyable, less regrets.

8 minutes ago, Kinkstaah said:

Then you're in for a rough spot.

I would legitimately consider the crazy path of a BMW DCT conversion. Anything else is going to be underwhelming. Sensible me says buy a car with a decent auto in it. A V8 10 speed mustang is going to be a lot more fun and a lot more fast, and a lot more everything than the anguish of going down this path.

It really depends on how irrationally compulsive you are with regards to keeping a R34, or whether you want what an R34 can do. If in your mind this is a 100K, once in a lifetime car, BMW DCT is your answer. If logic is being applied in any way, shape, or form... A10 Mustang or one of the many other automatic-optioned vehicles is going to be far faster, simpler, easier, more enjoyable, less regrets.

I would sell it tomorrow if I could get what I wanted for it lol. But I'm so far invested that 

Ahhh. Greg's rage is palpable from here.

A version of Greg's ragey recommendation would be to look at https://support.haltech.com/portal/en/kb/articles/transmission-control and see that it should be possible to get this transmission (or, more sensibly, a turbo transmission, for the longevity reasons raged about) working direct from a Haltech ECU.

Having said that, in light of

22 hours ago, theonlypancakeofdoom said:

@GTSBoy so are you saying that if I got rid of the tcu that the haltech could also control gearing? If so why in the world did my Tuner not do that in the first place?

I can't speak for your tuner's willingness to get involved in trying to program the transmission control. He might not know that it's possible. He might be scared, or too lazy, or any of a number of other reasons.

Regardless, as per Greg's rage out - there is wiring to be done. You have to obtain all the wiring that is currently present at the TCU, work out which wire is which input and which output (and which might be able to be ignored, if they were originally signals to/from the ECU) and then marshal them to the Haltech.

But.....this now I think leads us to the answer. The TCU is probably having a shit fit because you have removed the factory ECU. It will not be happy about that, because they like to talk to each other. The TCU relies on some info from the ECU to do its thing, and not having that would be enough to make it go to limp mode. So, some of Greg's rant regarding putting the factory ECU back in, in parallel with the Haltech would be a (shitty) path forward.

Just wire it to the Haltech and get someone competent to set it up.

  • Like 1

OK so update after today. Have plugged in a new tcu and actually have access to all gears and car shifts now. Still has AT light on but I assume that's now because this is a plain tcu and doesn't have any sort of tune on it

 

 

 

 

 

 

 

 

1 hour ago, GTSBoy said:

Ahhh. Greg's rage is palpable from here.

Just wire it to the Haltech and get someone competent to set it up.

Not really rage, but "I turboed my NA auto and it doesnt work now" is a thing. Because people do this cheaply (not necessarily OP) it is generally "how much of my original NA car can I retain?"

Which is effectively nothing. It's _probably_ still cheaper to sell the NA and buy a turbo 😛

Still does not solve the issue of the cheese gearbox which won't survive 150kw, let alone whatever the forged motor is wanting to be. Haltech when I did it, did _not_ have an automatic gearbox controllable ECU for sale. Nobody did...

If the elite can do it, do it. The main issue will be finding an auto elec at $150/hr with the confidence to give this a try, but once you do it is fairly straightforward as long as the auto (any auto) has its inputs in the realm it likes. It just won't, and cannot, and never will be a straightforward plug and play solution.

Until someone makes an adapter I suppose, to go from the NA TCM to the GTT OEM ECU...

 

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • For these last 7 years of ownership, I've always had to use a small scissor jack under one of the front tow hooks to raise the front just enough so my low-profile jack fits under to reach my subframe jack point. I'm beginning to get annoyed of always having to do this. Are there any lower low-profile jacks that fit under the gtr lip on a dropped car?
    • Seat of the pants assessment of the new intake: The car is way less "doughy" when hitting the loud pedal, especially off idle when stopped or in traffic, I did use a cheapo lazer thermal thingo to measure the temp around where the pod filter got its air, it was between 55 - 60°C, in saying this the car was shut off and not moving, so the OEM intake pipe was not supplying any fresh air to where the pod was when the car was at least moving A weird bonus was induction noise on the throttle in the cabin increased a bit,  I was worried that I was actually going to lose some of that induction noise I love so much, outside though, when I got the daughter to do a WOT drive by pass for me, the induction noise has increased alot when on the throttle, not quite ITB doort, but well up there I'm extremely happy with the results and have been exploring the country roads in the region  As for house mods: 1.New front fence is up and is awesome, it really upgraded how the joint looks from the street, and the added security is nice 2. Electricians have replace some interior lights, and with more lighting in the garage, a few new motion detecting lights out the front above the garage, front room, and at the front door, which I have already found heaps helpful coming and going, also now has fancy pants CCTV all round the house The only hold point for power though is the solar and batteries due to supply issues, although this will happen over the next few weeks 3. I have done a heap of landscaping out the front and I'm almost ready to do a new small retaining wall with some nice blocks to replace the brick and cemented in rocks around the raised garden beds cemented in river stone "was the fashion at the time" the house was built. I currently have a pallet of retaining wall blocks and 2 bulka bags of 20mm blue metal to replace the wood chip that is in the raised garden beds around the house 4. I now have 3 big raised garden beds for out the back to grow some vegetables, about 70cm high, 200cm long and 100cm wide 5. My 2 compost bins are already pretty full with brown, green and kitchen waste from the landscaping I'vedone so far, but they will probably take a few months to break down, so anything else that gets chopped, trimmed, and kitchen waste will just start filling the base of the raised garden beds to about 30cm before I start throwing 40cm of good compost, and stuff, for the vegetables to grow in, I'll need a few ton of compost and soil, but the local supplier can sent me bulka bags of the stuff Basically the logs, wood chips and a few strategically placed rocks for drainage, will give the beds some good organic materials down low to break down over time, and they will hold moisture during the warmer months to save the water in my big arse water tank if we don't get alot of rain So, all in all, the car and house mods are going well, and I'm really enjoying being retired, I sleep in too 0700 and slowly plod around inside until I feel like actually doing anything, and only work in the yard for as long as want, which has actually been alot over the last few weeks,  although when you look at it, it seems that not a huge amount of work has been done,  until I look at the before I started the work pics Happy days and good times indeed 
    • hahaha yeah. Plan is to get side skirts and probably just rear pods. But going to do them one-by-one. I've got a set that I really like from RHDJapen, but that one isn't shipped to AU. So need to find someone who can get it for me
    • Here's an idea, answer the questions I asked you as they are trying to work out WHY the LSD will be binding up in a straight line.
×
×
  • Create New...