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

    • Hi, is the HKS  Tower Bar still available ? negotiable ? 🤔
    • From there, it is really just test and assemble. Plug the adapter cables from the unit into the back of the screen, then the other side to the car harness. Don't forget all the other plugs too! Run the cables behind the unit and screw it back into place (4 screws) and you should now have 3 cables to run from the top screen to the android unit. I ran them along the DS of the other AV units in the gap between their backets and the console, and used some corrugated tubing on the sharp edges of the bracket so the wires were safe. Plug the centre console and lower screen in temporarily and turn the car to ACC, the AV should fire up as normal. Hold the back button for 3 sec and Android should appear on the top screen. You need to set the input to Aux for audio (more on that later). I put the unit under the AC duct in the centre console, with the wifi antenna on top of the AC duct near the shifter, the bluetooth antenna on the AC duct under the centre console The GPS unit on top of the DS to AC duct; they all seem to work OK there are are out of the way. Neat cable routing is a pain. For the drive recorder I mounted it near the rear view mirror and run the cable in the headlining, across the a pillar and then down the inside of the a pillar seal to the DS lower dash. From there it goes across and to one USB input for the unit. The second USB input is attached to the ECUtec OBD dongle and the 3rd goes to the USB bulkhead connected I added in the centre console. This is how the centre console looks "tidied" up Note I didn't install the provided speaker, didn't use the 2.5mm IPod in line or the piggyback loom for the Ipod or change any DIP switches; they seem to only be required if you need to use the Ipod input rather than the AUX input. That's it, install done, I'll follow up with a separate post on how the unit works, but in summary it retains all factory functions and inputs (so I still use my phone to the car for calls), reverse still works like factory etc.
    • Place the new daughterboard in the case and mount it using the 3 small black rivets provided, and reconnect the 3 factory ribbon cables to the new board Then, use the 3 piggyback cables from the daughterboard into the factory board on top (there are stand offs in the case to keep them apart. and remember to reconnect the antenna and rear cover fan wires. 1 screw to hold the motherboard in place. Before closing the case, make a hole in the sticker covering a hole in the case and run the cable for the android unit into the plug there. The video forgot this step, so did I, so will you probably. Then redo the 4 screws on back, 2 each top and bottom, 3 each side and put the 2 brackets back on.....all ready to go and not that tricky really.      
    • Onto the android unit. You need to remove the top screen because there is a daughterboard to put inside the case. Each side vent pops out from clips; start at the bottom and carefully remove upwards (use a trim remover tool to avoid breaking anything). Then the lower screen and controls come out, 4 screws, a couple of clips (including 3 flimsy ones at the top) and 3 plugs on the rear. Then the upper screen, 4 screws and a bunch of plugs and she is out. From there, remove the mounting brackets (2 screws each), 4 screws on the rear, 2 screws top and bottom and 3 screws holding in the small plates on each side. When you remove the back cover (tight fit), watch out for the power cable for the fan, I removed it so I could put the back aside. The mainboard is held in by 1 screw in the middle, 1 aerial at the top and 3 ribbon cables. If you've ever done any laptop stuff the ribbon cables are OK to work with, just pop up the retainer and they slide out. If you are not familiar just grab a 12 year old from an iphone factory, they will know how it works The case should now look like this:
    • Switching the console was tricky. First there were 6 screws to remove, and also the little adapter loom and its screws had to come out. Also don't forget to remove the 2 screws holding the central locking receiver. Then there are 4 clips on either side....these were very tight in this case and needed careful persuading with a long flat screw driver....some force required but not enough to break them...this was probably the fiddliest part of the whole job. In my case I needed both the wiring loom and the central locking receiver module to swap across to the new one. That was it for the console, so "assembly is the reverse of disassembly"
×
×
  • Create New...