What ECU should I use in my car?

Motec Plug in ECU

If you’re upgrading your car, then chances are you’re going to need to look at upgrading the ECU, or at least tuning it. What ECU should you use? Link, Motec, Haltech, Factory ECU reflash, Autronic, Life Racing, Chip tune…? There are countless ECUs on the market today. It can be confusing what brand, and even what type of ECU to choose for your project.

So what do I need to think about?

There are a ton of factors that come into choosing an ECU. Like any engine or car build as a whole, we recommend taking the time to plan EVERYTHING before you start. This will give you a really clear idea of where you’re going and what you want. Use this plan to figure out the finer details, including what ECU is required.

We’ll take a quick look at the factors you’ll need to think about when choosing an ECU.

Vehicle/Engine Combination

Pretty simple, that first thing to consider is the type of vehicle that you have and the engine that’s in it. If the engine you have is factory, then the wiring is likely factory. If the setup isn’t going to put huge demands on the ECU, then we’d be considering a Modified/Reflashed factory ECU or a Plug-in replacement ECU. A reflashed ECU is more common in modified vehicles with modern electrical systems that contain CAN-Bus and cannot be easily fitted with an aftermarket ECU.

If the Vehicle/Engine and engine wiring combination isn’t factory or it is going to be highly modified, we’d take a different approach. In this instance a full Wire-in ECU would typically be used to control the engine.

Purpose

It’s always important to match the purpose of the vehicle with the ECU selected. We usually find that a typical road car that goes to the track and back doesn’t require a Le-Mans level ECU, and that would only serve to add costs and a head ache.

In New Zealand, the ‘go-to’ brand is a Link ECU. This ECU covers a good section of the street and mid-end race car market, however wouldn’t suit the purpose of being used in a Le-Mans level race car.

In the same vein, we also see customers upgrading their ECU, when the purpose is only to be a road car with increased performance. In some examples, the factory ECU can be used to achieve similar/the same performance increase as an aftermarket ECU.

Consideration should also be made surround the environment the ECU will be subject to. If the purpose of the ECU is to run a jet-boat, then the ECU selected should be proof.

We recommend doing research and discussing options with your tuner before making a purchase.

Options

Once you’ve thought about the vehicle, engine and purpose of the vehicle, we recommend researching and compiling a list specific options that may suit your setup. An example of what this may look like has been listed, in no particular order:

Reflash factory ECU

  • ECUTEK software
  • Opensource software
  • Alientech tuning software

Chip factory ECU

  • Crome tuning
  • Hondata

Wire-in ECU

  • Link ECU G4+ Fury
  • Link ECU G4+ Storm
  • Haltech Elite 500
  • Motec M130
  • Motec M800

Plug-in ECU

  • Motec M800 Plug-in
  • Emtron Plug in
  • Link ECU G4+ Plug In
  • Haltech Elite Plug and Play

Inputs/Outputs

Now we’ve go options on the table, we need to look at each ECUs capability compared to what we need the ECU to do for us. The first thing to look at is the inputs and outputs.

Again, we suggest making a list using a spreadsheet, and comparing it to each ECUs offerings. We have a sample bellow:

In/Output ECU Pins Required (names may vary)
4x Ignition Coils 4x Ignition driver
4x Injectors 4x Fuel driver
Boost control solenoid Auxiliary output
Idle valve Auxiliary output
Check engine light Auxiliary output
Fuel pump Auxiliary output
Engine fan Auxiliary output
Tacho Auxiliary output
CAN Lambda unit CAN Signal -, CAN Signal +
CAN Racedash CAN Signal -, CAN Signal +
Coolant temp sensor Sensor Ground, Analogue Temperature
Crank angle sensor Trigger 2, Sensor Ground
Cam angle sensor Trigger 1, Sensor Ground
Intake air temp sensor Sensor Ground, Analogue Temperature
Fuel pressure sensor +5V, Sensor Ground, Analogue Voltage
Boost control switch Sensor Ground, Digital Input
MAP sensor +5V, Sensor Ground, Analogue Voltage
Throttle position sensor +5V, Sensor Ground, Analogue Voltage

Once you’ve done this, check all the ECUs you’re considering and ensure that they will have the required inputs and outputs. We recommend choosing an ECU that will provide a few additional inputs and outputs in the case you want or need to expand in the future.

Functions

It’s important that the ECU chosen will cater to all the functions required of it. Whilst not as in-depth, you’ll need to check for vehicle specific requirements. This will vary, but may include motorsport functions (launch control, antilag etc), Fly by wire, traction control, CAN Bus communication and internal lambda control. This would be the perfect time to get in touch with your engine builder, tuner and ECU installer.

Price

Price is usually an important factor when considering an ECU, however it’s important to ensure price does not compromise or cause limitations in the long term. Most ECU manufactures have a wide range of ECUs that cater to varying needs and price-points.

Typical ECU Types

Most aftermarket ECU manufacturers offer the easy-to-install plug-in option as well as a complete wire-in unit. These ECUs both have a place in the market and it reasonably easy to decide that the right one is for you.

Plug-in ECU

A Plug-in ECU is the most common type of ECU we install as they’re easy and cost effective. They generally replace the factory ECU and plug directly into the factory wiring, and have an expansion harness for wiring in additional sensors, switches or outputs. The plug in option is good if your wiring loom is in good condition and you only require a minimal amount of additional inputs and outputs.

Wire-in ECU

We typically use a wire in ECU in an application that doesn’t have a plug in available, or it’s a little more serious. Check out our wire in ECU page for more details. In general we use these on vehicles that have had an engine transplant, are a full race car, are building a full wiring harness or need a inputs and outputs that a plug-in ECU does not cater to.

Reflashable factory ECU

Many modern vehicles have a ‘re-flashable’ or tunable ECU. These are great for a reasonably modified vehicle, however have limitations. We typically use these on modern vehicles that are expensive or difficult to upgrade to an aftermarket ECU, or mildly modified engines.

Need help picking an ECU?

It can be a daunting task picking an ECU. We recommend talking to your tuner and ECU installer whilst selecting an ECU. Be sure to contact us if you have any questions!

About the author, Julius

Julius provides technical support and expertise to Possum Bourne Motorsport. He's been involved with the industry since 2009 and has stamped his mark as an industry leader.

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