HELP r34 n/a turbo conversation

[Duncan]

So, in summary, there is a fair bit more work before this will run OK. Whoever gave you the idea that you could bolt on the turbo, injectors and ECU and it would run skipped a few steps.

1. One way or another you need to match the ECU wiring to the ECU.  You need the pin outs for both ECUs (old and new) and compare every difference. You either need to cut and rejoin your current loom at the ECU to match the new pins, or you need the ECU loom that matches your ECU, and then change a few of it's connections at the other end where they are different (and they will be). You may need help from someone who has done this before if that doesn't make sense

2. There are at least a few mechanical/electrical differences to deal with. I'm not familiar with this particular swap but the guys mentioned the boost sensor, I would expect there is also a difference with fuel pressure regulator needing to be a turbo version and have a boost input, some sort of boost controller, fuel pump is probably different, air flow meter might be different as well? 

3. The ECU you have may still not run the DE engine well due to differences in cam, VCT and compression. You will probably need a nistune at a minimum to get in running well. Since it is a manual ECU it won't talk to the auto; it will work but it won't give smooth shifts because the trans can't tell the engine it is changing gears and to reduce power (timing) momentarily

There is still a big job ahead to get it running properly, you've gone down a difficult path. Realistically you need to find some other way to get to work for a few weeks...

[Amghugs]

if i put a nistune on the ecu will it work? the ecu is for a manual though and my car is auto..

[GTSBoy]

R34 NA RB25s have a separate TCU in the car for the auto. On the turbos, the TCU is a board inside the ECU. The only real question is whether the turbo manual ECU will talk nice on the system bus to the TCU. I would expect that it probably would not. The reason is that the turbo auto ECU talks to the TCU internally (whispering in its own ear). The turbo manual ECU does not expect to have to talk to any TCU, so probably doesn't send or receive ANY auto trans related messages. That might leave your auto's TCU struggling to work out what's going on.

I predict bad things because of that.

And it's not as if you can get an auto image dropped into a Nistuned manual ECU either. You can, there's nothing stopping you, but I would not expect it to talk to the external TCU, because it would be just talking inside the ECU - whispering in an ear with an earplug in it (or an ear that looks a lot like Van Gogh's.)

The reverse situation is easy. I have an auto R34 ECU (with TCU inside) running the engine with a manual gearbox. That works because I am the TCU.

[Duncan]

Nistune in the new ECU will resolve my point 3 above, but it won't correct any physical wiring differences. On the other hand, if you can nistune your original ECU than both 1 and 3 are covered off.

[Rusty Nuts]

On 7/23/2019 at 9:05 AM, Duncan said:

Since it is a manual ECU it won't talk to the auto; it will work but it won't give smooth shifts because the trans can't tell the engine it is changing gears and to reduce power (timing) momentarily

With due respect, this is simply wrong. My experience from this conversion, the trans went into limp mode and was stuck in third all other gears except reverse were unavailable.

[Rusty Nuts]

On 7/23/2019 at 9:05 AM, Duncan said:

One way or another you need to match the ECU wiring to the ECU.  You need the pin outs for both ECUs (old and new) and compare every difference. You either need to cut and rejoin your current loom at the ECU to match the new pins

This was good advice, I PM'ed the young fella the complete R34 workshop manual and gave him the same advice, he PM'ed me back that he had no idea what he was looking for. So I PM'ed him all the pin numbers he should look at, but the eureka lights still did not come on!

Perhaps he could get some advice from Nistune on whether his original N/A ECU could be tuned, the VCT timing exists and could be changed, the boost control could be added using the variable inlet pinout. But would have to figure out fuel pump output for turbo. Obviously the ECU would need to be JECS and not Hitachi

Edited July 24, 2019 by Rusty Nuts

[Duncan]

24 minutes ago, Rusty Nuts said:

With due respect, this is simply wrong. My experience from this conversion, the trans went into limp mode and was stuck in third all other gears except reverse were unavailable.

Fair enough and thanks for saying. My experience is with Stagea W34 not Skyline R34. They run fine with manual computers and auto trans but it sounds like there are differences in later model/R34. 

Also, this suggests the Stagea ECU he has will not do the job with the later R34 auto trans for the same reason.

[Rusty Nuts]

8 minutes ago, Duncan said:

Also, this suggests the Stagea ECU he has will not do the job with the later R34 auto trans for the same reason

I have PM'ed him to find out whether his old N/A ECU was a JECS then advised him to talk to Nistune as to possibilities.

[Kinkstaah]

It IS possible to use an GTT ECU's 'TCM' I.e the inbuilt pins on the ECU)

to drive the n/a gearbox. Yes you can just bypass the n/a TCM and wire it to the GTT ECU.

The inputs of the n/a TCM DO translate to the extra pins of the R34 GTT auto ECU.

If you have a manual engine ECU tho then GL to you. Aftermarket auto ECU's do exist and DO work, but its utterly dumb when 'use anything other than the n/a auto gearbox' is by FAR the best solution.

[BK]

I think that's the point though, as in he's trying to avoid rewiring the auto tcu module directly to an auto turbo ecu directly.

I think that is what is going to have to be done in this situation though as you've pointed out.

[GTSBoy]

Yeah, I wasn't even going to go there!

[admS15]

What's that old saying. You can lead a horse to water, something something..

[GTSBoy]

You can lead a whore to culture, but you can't make her think.

[Kinkstaah]

I say this here because to his credit he did search and found I encountered the same issue and solved it back in the day.

I found that out by reverse engineering how my aftermarket transmission ECU had been setup and working. But really, the NA gearbox is a piece of garbage, and the GTT one while stronger when built (Mine is still going strong in the UK where I sold it....) pales in comparison. The answer is manual. And if you can't drive manual, have fun learning because it is fun and jesus the car is better manual than it ever was auto. The skyline gearboxes are not exactly lovely DCT's.

But yes in theory it can be done....  but in reality, ANY time or money spent working it out should be deferred to putting a manual gearbox in.

[Dil-Dog]

@Amghugs I private messaged you!