As newer and more powerful factory ECUs are being produced it can be a challenge to determine when the right time to switch to an aftermarket. We’re breaking it down and talking about what and when you might want to consider an aftermarket ECU.

When to switch to an aftermarket ECU

Factory ECUs do a great job of managing the engine parameters in an OEM environment. However, when you start to exceed the limitations of the factory ECU you should look into the aftermarket. You can scale a tune to stay inside of these standalone ECU parameters but it will ultimately lose resolution in the long run. Safety also becomes a major concern when it comes to pushing the limitations of the factory ECU. When a boundary is pushed too far it may cause the factory ECU to fault into a “limp home” mode or create an unsafe driving condition for the operator.

Vehicle Specific Limitations

Below are some examples of newer platforms that require the help of an aftermarket ECU to aid in the limitations that the ECU or OEM parts have.

2013+ Dodge Viper - In forced induction applications the Factory MAF sensor range is exceeded and causes a “limp home” condition. There is currently no way to rescale the factory tables without losing resolution to help solve this condition. This is where running a Motec or a ProEFI system comes into play, two of the more popular upgrades.

2014+ Gen V LT Engine-Based Vehicles - When making “high” horsepower numbers with a Gen V platform it can be easy to reach the limitations of the factory fuel system. Even with a larger low side fuel pump and a camshaft with a larger fuel lobe for the high side fuel pump you can still outrun the fuel system around the 900-1000rwhp mark. This is where an aftermarket ECU like the Prospeed ACM comes into play. Its main role is to supply the vehicle with fuel via port injection. This ECU also allows the user to set up boost control, nitrous control, methanol control, as well as a number of other functions.

Aftermarket Functions

ProEFI, Motec, AEM, Haltech, Holley EFI, Megasquirt

These are a few of the names you might hear when looking into running an aftermarket ECU. Aftermarket ECUs come in many different shapes and sizes. They’re typically used on vehicles with engine swaps, vehicles with computers that aren’t programmable, application specific vehicles that require a large number of inputs and outputs for precision control over power management strategies, and as full-on replacements for factory ECUs that have exceeded their limitations.

Determining Which Aftermarket Computer to Use

There are several important questions you will need to think about before approaching the realm of aftermarket ECUs. From here you can decide which manufacturer to you use.

• What do I need to control?

While most swap vehicles are only looking to control Fuel, Air, and, this means they won’t need to run as complex of an aftermarket ECU.  By contrast, an X275 drag car may need to have precision control over power management strategies (such as traction control or boost controls) to run its best time at the track.

Another example would be aftermarket ECUs like ProEFI or Motec, which use CAN bus communication to control the same features that the factory ECU handles for a more seamless integration. This is handy when running an aftermarket ECU on a late model vehicle that has multiple creature comforts that will still need to be controlled when the factory ECU is no longer used, a different scenario than a swap vehicle’s needs.

• Do I need useful features like weatherproofing or power management strategies?

Several ECU manufacturers feature shockproof and weatherproof systems in their lineups. This means you can mount the ECU in the engine bay or in a location that wouldn’t normally work from an electronics durability standpoint. Not only does this allow you to mount the ECU where the elements can’t get to it, but it also cuts down on the length of wire needed for most of the ECU connector harnesses, and allows you to find an easily accessible location to mount the ECU should you need to access it in the future. When it comes to power management, you should ask yourself how in depth you need these strategies to be. Most ECU companies have traction control and boost control strategies, but how does the ECU control them? Some examples of a more in-depth power management strategy would be Boost by Gear, Boost by MPH, Boost by Time, Power Wheelie Management, Power Management by Driven and Non-driven wheel speed, etc. These strategies can be enabled using several different sensors to provide input to the ECU, so it can make an adjustment on the fly based on its configuration.

• What safeties can I set up within the software to help save my investment?

At the point of switching to an aftermarket ECU it’s safe to say you have put a bit of money and effort into your build. The best way to protect your investment is to enable the safety features and warning systems that some manufacturers have to offer. Useful safety features like Knock Detection, fault code display, or a warning you if are out of Nitrous, Fuel, or Methanol can be found on ProEFI and Motec ECUs and can be configured to work with multiple aftermarket displays.  On some expensive engine builds, these safety features alone make it worthwhile to switch from a factory ECU.

• Getting Comfortable

If at first, you don’t understand the software, it’s okay. Most aftermarket ECUs have specialized functions and nomenclature that is brand specific. The first thing you should look for is if the manufacturer has a training course or literature that you can read through to better understand their product. The next step would be seeing if they supply you with a base file for your specific vehicle or if they have a support line established in case you become stuck or experience a bug in the software. Last but not least - see if there is a community of individuals who also use the manufacturers’ products and can give their own feedback on their experiences.

Choosing which ECU features and strategies are a necessity to you is the most important step in the selection process. Whether you are looking to use a hyper-control system like Haltech, Motec, and ProEFI or an ease-of-use but powerful systems like Holley EFI and Megasquirt you can take your time, evaluate what’s right for your project, and then get comfortable with your new Aftermarket EFI control system.