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This article will help you decide whether or not the Nexus R3 is the right VCU for your application, and if not, what other options are available to you from Haltech. We’ve already covered all the specs and features of the Nexus R3 in another article, we highly recommend reading it first.





From single cylinder motorcycle engines, through to 4, 6 or 8 cylinder engines in Straight, V or Boxer configurations and everything in between –  the Nexus R3 will run most popular performance engines. 

If your engine is not listed on our website, just contact us via email or call any of our regional Haltech offices to confirm whether or not one of our ECUs can support your engine configuration and the sensors fitted to it.



The Nexus R3 can control port-injected engines up to 8 cylinders in Sequential operation (meaning each injector and each coil would be fired individually), and up to 12-cylinder engines in Semi-Sequential operation.

Things get a little more complicated if you want to run Staged Injection with two injectors per cylinder. The Nexus R3 has a total of eight injector outputs so it can fire two injectors per cylinder in sequential mode on engines up to four cylinders. On a six or eight cylinder engine you can still perform Staged Injection, but not in sequential mode – this is where we’d probably recommend stepping up to the Nexus R5.


Popular Applications

 Performance six cylinder engines like Toyota’s 2JZ, Nissan’s RB and Ford’s Barra that come with sequential injection and one injector per cylinder from factory – go with the Nexus R3. For two injectors per cylinder setup on these engines – step up to the Nexus R5.
The same rule applies to all V8 engines like the GM LS, Ford’s Godzilla or Coyote. The R3 will handle single injector setups while staged two-injector setups should go with the Nexus R5.







Mazda’s rotary engines run two injectors and two spark plugs per rotor so with 8 injector outputs and 8 ignition outputs, the Nexus R3 will control a single, twin, triple or quad rotor engine. However, if you’re planning to run more than 8 injectors on your rotor, you’re entering the Nexus R5 territory.



Well, with 10 PDM channels, the R3 might fall short of being able to run the entire electrical system of your car, front to back. You have two options here:  First – is to expand the PDM channels available to you by adding a PD16 Power distribution module to your R3. 

Use the R3 to control all the engine functions and leave all the body functions like headlights, tail lights, indicators, wipers, and basically anything in the car that is normally powered through a conventional relay or fuse to the PD16. This is still an elegant and easy to setup that you control fully through the R3 within the NSP (or Nexus Software Programmer) software. 

The other option is to use the R5 which, with its 15 PDM channels can control the entire vehicle. Keep in mind that you can also add up to four PD16s to your Nexus R5 should you need it.



This is probably one of the least talked about attributes of the Haltech Nexus system – its versatility, and its almost infinite expandability.  You can add up to four PD16s to your Nexus R3. Granted, you probably wouldn’t do that simply because at that point you’ll be better off stepping up to an R5 but the option is there if you need it. The same applies to the R5 – it can also be expanded with up to four PD16s. 

You can also expand the functionality of your Nexus R3 with CAN keypads. Both the R3 and the R5 accept up to four keypads – that’s two 8-button and two 15-button keypads.



The Nexus series VCUs use Haltech latest technology and are the most advanced computers in the range. So where does that leave the Elite series ECUs? As it happens there are still plenty of cases where you could opt for an Elite instead of a Nexus.

As good as they are, the Nexus series VCUs are still relatively new on the market. What that means is that they are primarily geared toward new builds, re-wired from the ground up. The Elite series has been around for well over a decade and over the years it has built up a huge assortment of engine and car specific wiring options. 

Along with the standard universal wiring looms, the Elite series ECUs are available with fully terminated engine harnesses for popular engines like the LS, RB, 2JZ, Barra or Mazda’s 13B. The Elite series ECUs also have over 40 model-specific Plug and Play adaptor kits that plug directly into the OEM harness. So if you’re using an existing engine harness or doing a simple EFI conversion or engine swap, then the Elite series ECUs are still your best option. And remember you can expand the functionality of your Elite ECU by adding a PD16, or a keypad.


The Budget Option 

Let’s not forget the price. If you’re on a budget, the entry level single connector Elite ECUs offer great value for money while still running the same NSP software that controls the Nexus Series.



Q: I want to swap my Elite 2500 for a Nexus R3, can I repin the existing wiring?
Q: I repin anElite Plug’n’Play adaptor to suit the R3? 

Both the Elite and the Nexus series use the AMP 1.0mm Superseal pins. This means you can pull the pins out of the Elite connectors and push them into the Nexus plugs. Keep in mind the keyways on the plugs for the R3 and R5 are different from each other (this is so you can’t push the wrong plug into the wrong socket). The R3 and R5 have heavy SurLok connectors that would need to be added in order to supply the current required associated with the PDM part of the R3 and R5.

Q: Can the R3 control E-gates?

The R3 can control up to 2 E-gates, the same as the R5. Each E-gate requires 2 analog inputs (used for temperature and position sensing) as well as 2 outputs to control the DC motor.

Q: Can we do Torque Management Driveshaft RPM targeting with the R3?

Yes, in a drag racing application we can configure a Target Engine RPM and a Target Driveshaft RPM then set up fuel, ignition and boost cuts as well as limits in order to achieve the desired targets.

Q: Does the R3 do Automatic Transmission Control?

The R3 can control A340, 4L60, 4L80, ZF6HP, or you can configure a custom automatic transmission with up to 10 speeds, torque converter lockup, line pressure control, accumulator pressure control and everything in between. There are even specific control strategies for Liberty and Lenco drag racing gearboxes.

Q: Does the R3 control Nissan’s ATTESA 4WD system?

Yes, you can map the 4WD system vs. wheel slip, acceleration, steering angle or a combination of these.

Q: What is the NSP Quick Tune Feature and how does it work?

The Quick Tune feature works in two different ways. If you press Q while the engine is running, the ECU will look at the current air-fuel ratio, then look at the target air-fuel ratio and make a change to the fuel map in order to make them the same. Alternatively it allows you to take a log of the current air fuel ratios, across as many engine load and RPM sites as you like. You can then press R in order to make bulk changes to all the sites you have visited – this significantly cuts down the fuel map tuning process. 

Q: Can the R3 detect individual cylinder knock? Can it control individual cylinder knock retard?

The R3 and R5 both detect knock per cylinder, meaning you will know which cylinder is the one making the scary noises. Both the R3 and R5 offer short and long term knock control. The short term control takes a programmed amount of ignition timing out on initial knock, while the long term knock control will fill out a 3D table per cylinder of knock trims. You can then choose to apply common values between the long term knock tables to the base ignition map.

Next article Technical: What Camshaft Is Right For you?

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