ThunderMax 2021-Up Touring® Models (w/o Center Cool Motor)

ThunderMax 309-591 ECM for 2021-Up Touring® Models

For applications without center-cooled engines. Excludes 2023.5-up center-cooled models—see part number 309-605.

Replace your factory engine control module with ThunderMax EFI management and AutoTune technology. The 309-591 uses wide-band oxygen sensor feedback to adjust fueling as you ride, helping your motorcycle respond to changing conditions and your engine’s configuration.

How AutoTune works

Start by selecting and loading a basemap suited to your motorcycle’s engine, exhaust, and other modifications. After initial setup, AutoTune uses exhaust oxygen readings to make ongoing air/fuel ratio corrections while you ride.

A basemap provides the starting calibration. AutoTune refines fueling from that starting point.

Key features

• Complete replacement ECM: Replaces the factory module and connects to the motorcycle’s wiring harness.
• Wide-band AutoTune: Uses 18 mm oxygen sensors to monitor exhaust oxygen and make fueling corrections.
• Knock correction: Uses the factory knock sensors to detect engine knock and automatically adjust ignition timing.
• Adjustable settings: ThunderMax software provides access to air/fuel targets, ignition timing, idle speed, rev limits, and other tuning parameters.
• Diagnostics and data logging: Monitor engine information and record operating data to help evaluate performance and support troubleshooting.

What’s included

• ThunderMax ECM with AutoTune
• Wide-band oxygen sensors
• Plug-in harness
• USB communication cable

Check your exhaust before ordering

ThunderMax requires compatible 18 mm oxygen sensor ports in the exhaust head pipes. Verify your exhaust’s port size before installation.

If your exhaust has smaller ports or no suitable sensor ports, modifications may be required. Weld-in sensor bungs are not included.

Installation and setup

Review the application-specific installation instructions before beginning. Installation includes replacing the factory ECM, fitting the oxygen sensors, and completing the software setup.

Download ThunderMax software · View 309-591 installation instructions

Emissions Notice

This product is intended for "RACE READY" vehicles only and is not for sale or use on vehicles otherwise subject to emission control requirements.  In the state of California, this product should not be used on any vehicle that is registered for use on public roads. Please view the ThunderMax 50 application guide for "STREET APPROVED" & ARB compliant products.