ECUs, CDIs & Computer Modules
About ECUs, CDIs & Computer Modules
ECUs, CDIs and similar modules are the electronic brains of the engine. They control when the spark fires and, on fuel-injected bikes, how much fuel is injected. Riders buy them to replace a failed unit, to add a programmable ignition, or to change the fuel and spark settings.
The first split is the kind of unit. A CDI or ignition module controls spark timing and is common on simpler and older ignitions. An engine control unit, or ECU, manages the ignition and the fuel injection together. The listings here also include fuel processors, which adjust fuel injection signals, rev boxes, and engine control module kits such as the ThunderMax with auto tune. Many are listed for Harley-Davidson, Honda, Yamaha, Suzuki, Kawasaki, Indian and Polaris models. Some plug in, while others need programming or tuning. Match the unit to the exact model and year, and check any note about off-road or competition use.
Brands in this category include GET, Custom Dynamics, S&S Cycle, Dynojet and Thundermax. Pick your bike in the Ride Finder at the top of the page. A module depends on the rest of the ignition, so see Ignition Coils, Electrical & Ignition Sensors & Switches and Ignition Kits. The whole group is Electrical & Ignition Components.
FAQs on ECUs, CDIs and ignition modules
What is the difference between an ECU and a CDI?
A CDI is an ignition unit that stores energy and releases it to the coil to fire the spark. An ECU is a computer that controls ignition and, on fuel-injected bikes, fuel as well. Which one you need depends on how your engine is built.
Does a performance ignition module need tuning?
Some are plug-in and ready, and others have adjustable maps or need a tune. Read the listing and the maker's instructions for your model, and set it up as directed before riding hard.
What is a fuel processor?
A fuel processor is a module that changes the signals going to the fuel injectors to adjust the air-fuel mixture. It works alongside the stock ECU rather than replacing it, and it must be set up for your model.
Can I use an ECU from another model or year?
Not safely. An ECU is set up in software for a particular engine, set of sensors and wiring, so a unit from another model or year may not work or may run the engine badly. Use the unit listed for your bike.
Are aftermarket engine control modules allowed on the street?
Some are sold for competition or off-road use only. Check the product notes and your local emissions rules before you buy one for a street bike.
