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RB25det NEO Wiring


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Hi everyone

Im new to this forum, have just recently purchased my first link ecu xtreme g4+, iv been building my car for a while now and now down to last stages, I would like to give a go at wiring the engine up myself. I have never wired a engine up before from scratch, but have modified looms before when transplanting a engine, so I have more than basic electrical knowledge, nearly a fully qualified mechanic after 4 years training, am really hooked into performance modifications after building this car from scratch, all work done by my own hands. I want a career in Performance tuning, been reading as much as I can but a lot goes over my head, as expected when having no one to teach you (boss is to old for this stuff :P) I asked my local tuner if he could tune my car and if I could watch to understand things, but he said no due to osh reasons and not giving away his secrets and missing something out from me watching him, which I fully understand.

Modifications are:

  • stock internal r34 rb25det neo
  • custom holset HRC35/2 twin scroll turbo
  • 1000cc bosch injectors
  • raceworks twin entry fuel rail
  • -6 fuel lines
  • turbosmart 1200 fpr
  • custom ffp
  • custom exhaust top mount twin scroll manifold
  • 3inc straight pipe
  • front mount intercooler
  • standard throttle body
  • 044 fuel pump
  • running tablet for link race display
  • Made and installed a homolgated rollcage  

Being built for one purpose only drifting. running e85 fuel wanting 400hp for reliability

So am drawing diagrams planning how I will make this custom loom to make things easier, im keeping things simple as I can, Have a main, ingtion, fuel, fuel pump and fan relays with inbuilt fuses, main kill switch, switch for ingtion and fuel pumps. 

I have worked out the wiring for injectors, coils, tps, map, engine, air and oil temp, oil pressure

I am unsure how to connect the cas correctly, exhaust gas sensor, fuel and fan ground signal for relay, boost switch and boost controller, switch for two fuels for different tunes, e85 race fuel and pump fuel.

Now I have a lot of wires left over what can I do with them all as in, warning lights for oil pressure engine temp etc, OBD2??


I cant wait to plug my computer into the link to get everything ready for start up and see what I can do and learn more. How have other people found the xtreme? and what do people think of the combo I have or what I could do to make better, as in other sensors, bolt ons, information to read for beginners etc etc. The engine will be stripped down for a full rebuild at some stage for big hp.

Would like to thank everyone in advance, as I can already see from reading a few posts there are some very clued up, experienced tuners out there that I would be super keen to sit down days on end learning from you!

Cheers Matt :DB)




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Good day to you Matt.

I'm happy that you are super enthusiastic about your investment with the Link brand. I'm sure the online community here on this forum will be more than happy to assist you along the way to ensure that your end user experience using the G4+ is the best possible.

You've said a fair bit with your introduction so it's going to be difficult to give a response that hasn't missed anything. Having said this, you sound as though you are quite comfortable with the basics of automotive wiring. To add to this, the G4+ ecus have a built in output test function which allows you to verify the wiring work completed as well as the device itself. It is available in a simple on and off manner, or you can simulate a low frequency PWM signal. This will be enough to validate the devices such the fuel pump, ignition coils, injectors as well as solenoids like a boost controller actuator are working as they should. If you have specific follow up questions you may post them accordingly.

I will also advise that you get the PCLink software installed to familiarize yourself with it, in particular, the help file is exceptionally written and can give great insight. You may use the help file as a search, or you may press F1 to activate the relative help documentation for an active field within the software. This can assist you with the wiring for the CAS you mentioned. I am assuming that the CAS has a Hall Effect/Optical sensor which will need a +12 volt signal with a matching ground installed. The CAS should output a signal for engine speed as well as a cylinder reference signal and these will need to go to the trigger 1 and trigger 2 inputs on the G4+ ECU.

Lastly, you mentioned that there were a fair bit of spare wires left over from the allocations you made for your setup. It is possible to make use of the spare outputs to power lamp/LED bulbs as warning signals reflecting specific operational conditions of the engine. You may also use engine protection strategies through the available general purpose output tables. You may read up on this through GP output section of the help file.

For help understanding EFI calibration I will openly recommend the High Performance Academy (www.hpacademy.com). You may find quite a few courses available which cater to a variety of EFI related topics. There's even a course dedicated to learning the G4+ family of Link ecus. The firmware used for the course is quite older than what we have today, but the course material is very much applicable. 

My apologies if I missed anything, and as I mentioned previously, please feel free to post follow up response so that you may be better assisted.


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