R34 gt4 non turbo to rb25det conversion

[Mussy]

Hi, was wondering if anyone can help with my issue would be much appreciated.

r34 gt4 4wd non turbo originally

installed stagea 2.5 turbo 4wd engine into r34

got it running just fine with some niggly issues

few questions

idles at 900rpm cold or hot, ideally when cold should idle high and then drop. It sits consistently no missfire or cut off. Power to idle control valve is present, tps set correctly, diagnostics code 55 no faults. No engine light also.

 

currently using stagea turbo ecu would that cause a conflict?

 

injector resistor, not installed is this important? Will it need to be installed?

 

4wd light is on also , front abs sensors need replacing as they broke and are not on vehicle hence abs light is also on. 

 

Thank you in advance any support would really appreciate.

 

 

 

[GTSBoy]

1 hour ago, Mussy said:

currently using stagea turbo ecu would that cause a conflict?

No. Better than GTT ECU which would have a shit fit about not seeing the TCS system. Besides which, it's the right ECU for the engine, yeah?

 

1 hour ago, Mussy said:

idles at 900rpm cold or hot, ideally when cold should idle high and then drop. It sits consistently no missfire or cut off. Power to idle control valve is present, tps set correctly, diagnostics code 55 no faults. No engine light also.

If it's all working electrically, then expect that the IACV is dirty and stuck so that it won't close enough to drop the idle.

1 hour ago, Mussy said:

injector resistor, not installed is this important? Will it need to be installed?

What injector resistor? There is not supposed to be one.

1 hour ago, Mussy said:

4wd light is on also , front abs sensors need replacing as they broke and are not on vehicle hence abs light is also on. 

Well.....

 

[MBS206]

2 hours ago, GTSBoy said:

 

If it's all working electrically, then expect that the IACV is dirty and stuck so that it won't close enough to drop the idle.

 

Step one would be to unplug the IACV and see how low the idle drops. If the bypass screw isn't closed enough, it won't matter how well the IACV is working.

 

I do agree with pulling IACV and cleaning it though, would do it either way. Really should have been done before engine install into car.

[Mussy]

Hi there is power to idle control valve, issue is no cold start, it starts at 900rpm and will stay there.

 

changed idle control with another same issue

 

injector resistor is found on gtt models and stagea. Gt four non existent, with this car now turbo would it need this wiring in

[Mussy]

Unplugging iacv doesnt do anything no change

[GTSBoy]

47 minutes ago, Mussy said:

Hi there is power to idle control valve, issue is no cold start, it starts at 900rpm and will stay there.

OK, so the opposite problem of what I gathered (because I didn't read your OP properly). You see, 900 is high, so I presumed your problem was that it wasn't dropping down from 900 to the correct idle speed of 600-650.

So you actually have 2 problems.

The cold start on the Neo IACV is a wax pellet thermostat thingo that is heated by coolant. If you do not have coolant flow to it, then it simply won't close. So idle will stay high. The coolant path in these things can get plugged up. I had to extensively clean mine out after the engine swap to get it to flow coolant. Was full of red rusty deposits (as was the whole engine, which took ~5 coolant flushes to come clean). So....have a look.

Now, if the cold start valve is fully open, then that might explain the lack of dropping to proper idle speed. The ECU could be dialling the stepper back to minimum opening and not gaining control because the cold start is just too much for it.

[GTSBoy]

52 minutes ago, Mussy said:

injector resistor is found on gtt models and stagea

yeah. nah.

Here's the top part of the R34 ECU and engine wiring diagram. The injectors are on the left. See the resistor? No. I can't either. High impedence injectors just don't have them.

 

[Mussy]

This is the resistor found in engine bay that Iam askin about 

[Ben C34]

On 5/7/2023 at 6:55 PM, Mussy said:

This is the resistor found in engine bay that Iam askin about 

That's got to do with the auto gearbox.

[Mussy]

🙈 do the r34 gtt does not have any fuel resistors in place for the injectors?

When i google that image it comes back with injector resistor

 

 

 

[Ben C34]

That image is a fair bit different bro.

[GTSBoy]

11 minutes ago, Mussy said:

🙈 do the r34 gtt does not have any fuel resistors in place for the injectors?

So let's just pretend that I didn't post the actual wiring diagram.

[Duncan]

1 hour ago, Mussy said:

This is the resistor found in engine bay that Iam askin about 

Just to be clear, was that in your car or is it a sample pic?

Looks to me like an injector resistor pack

Either way, you need the wiring loom and engine to match, and it sounds like they do (plus, the engine is running OK). Therefore, I would not worry about anything that was in the car for the old engine setup

[Mussy]

sorry guys dont know how to respond to comments on here thanks for the wiring diagram, im confused as i have r34 gtt here with fuel resistor so i assumed i would need it for this car also.

 

it seems to be working just fine just want to be on safe side. Just need to sort this cold start issue out need it to idle high and then come down once warm

[GTSBoy]

I would like to point out that the RB26 injector resistor linked by OP is a rip off. US$165, but can get them here in Oz for AU$150 from Just Jap.

RB26 cars have injector resistors because they use low impedance injectors and the ECU actually wants to see high impedance. Nissan did some weird shit there to get the injectors to do the peak & hold stuff. There are actually 6 resistors in there. One for each injector, and that's why there are multiple wires in the lead and plug.

All other RBs use high impedance injectors. Therefore no resistor.

The resistor that you will see in the engine bay in other RB engined cars only has 2 wires. That one is the dropping resistor for the auto trans, as Ben said, and as shown in the manual on page AT-7.

[Mussy]

Hi alot of trouble shooting later, repaced the dump valve back to standard idles better no cutting off, still no cold start, changed iacv, coilpacks, theottle body, iat sensor, as inahve two sets of everything still no change.

 

now i may think it is ecu related as the ecu installed into r34 is  from a neo stage 4wd rb25det but it is auto my car is manual from factory.

 

Thanks for the reply guys dont know how to

reapons individually yet 🙈

 

attached is picture of ecu

[Mussy]

[Duncan]

A working auto ECU will run the car fine, I had the auto  one in my manual swapped stagea for a while

[GTSBoy]

Have you followed my other recommendation? Coolant flow?

[Mussy]

3 hours ago, GTSBoy said:

Have you followed my other recommendation? Coolant flow?

Hi yes fully cleaned, will remove today again and clean, have noticed when setting idle learn when i connect the tps plug revs increase ever so slightly,

will be checking neutral switch to pin 39 on ecu to ensure this is wired