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ThunderMax ECM With Auto Tune Closed Loop System
ThunderMax ECM With Auto Tune Closed Loop System
ThunderMax ECM With Auto Tune Closed Loop System
ThunderMax ECM With Auto Tune Closed Loop System
Made in the USA
Read ( 32 ) Reviews

ThunderMax ECM With Auto Tune Closed Loop System

J&P Cycles Part Number: 126-885

Manufacturer Part Number: 309-382


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Important Fitment Note

Will require the use of an exhaust system with 18mm sensor bungs or head pipes must be modified to accept 18mm sensors.


Description for ThunderMax ECM With Auto Tune Closed Loop System

• ThunderMax ECM with Auto-Tune module mounts conveniently in place of the factory ECM and plugs in to the existing harness

• Utilizes wide-band O2 sensors and works as a closed-loop control system to continuously self-adjust and properly tune the motorcycle’s air/fuel ratio for all riding conditions

• Easy installation: replace the factory ECM, install new O2 sensors and harness, load the correct map for your bike, and ride

• Includes ThunderMax ECM with Auto-Tune Module, plug-in harness and two wide-band sensors, TMax software and communication USB cable, Quick-Start Easy Install and Comprehensive User’s Manual, technical support and free software and updates

• Hundreds of maps available to download for your bike (based on model, engine size, exhaust system air cleaner, pistons, cams, etc.) load the map of your choice and the integral auto-tune will do the rest

• Improves throttle response, exhaust sound and driveability

• Does not require dyno tuning

• Rider can adjust idle speed, rev limit and speedometer calibration

• Adjustable front and rear cylinder AFR maps, ignition timing (spark) maps, and startup maps

• Works with all popular exhaust systems and is compatible with high-performance camshafts

• Supports turbo, nitrous and supercharger applications

• Software program allows live monitoring, recording and examination of diagnostic codes and datalogs including number of starts, engine temperature and rpm operation

• New maps, software, firmware updates, map analysis and tech support available online at no charge

• Will require the use of an exhaust system with 18mm sensor bungs or head pipes must be modified to accept 18mm sensors

Product Specs

Product Specs for ThunderMax ECM With Auto Tune Closed Loop System

Manufacturer Part Number:
Open or Closed Loop:
Sold in Units:
Warehouse Part Number:
With/Without 02 Sensor:
Fitment Note:

Will require the use of an exhaust system with 18mm sensor bungs or head pipes must be modified to accept 18mm sensors.

Fitment Questions?

With over 750 years of experience combined, our tech staff has the answers!

Compatible Models

Harley-Davidson® Models

  • Dyna Fat Bob FXDF : 2012–2017
  • Dyna Low Rider FXDL : 2012–2017
  • Dyna Street Bob FXDB : 2012–2017
  • Dyna Street Bob FXDBB : 2015–2016
  • Dyna Street Bob FXDBP : 2013–2016
  • Dyna Super Glide Custom Anniversary FXDC : 2013
  • Dyna Super Glide Custom FXDC : 2012–2014
  • Dyna Switchback FLD : 2012–2016
  • Dyna Wide Glide FXDWG : 2012–2017
  • Softail Blackline FXS : 2012–2013
  • Softail Breakout FXSB : 2013–2014
  • Softail Deluxe FLSTN : 2012–2015
  • Softail Fat Boy Anniversary FLSTF : 2013
  • Softail Fat Boy FLSTF : 2012–2015
  • Softail Fat Boy Lo Anniversary FLSTFB : 2013
  • Softail Fat Boy Lo FLSTFB : 2012–2015
  • Softail Heritage Classic Anniversary FLSTC : 2013
  • Softail Heritage Classic FLSTC : 2012–2015
  • Softail Slim FLS : 2012–2015
  • Softail Standard FXST : 2012–2015
  • Sportster 1200 Custom XL1200C : 2014–2020
  • Sportster 1200 Custom XL1200CA : 2014–2016
  • Sportster 1200 Custom XL1200CB : 2014–2017
  • Sportster 1200 Custom XL1200CP : 2014–2016
  • Sportster 1200 Forty Eight Anniversary XL1200X : 2018
  • Sportster 1200 Forty Eight Special XL1200XS : 2018–2020
  • Sportster 1200 Forty Eight XL1200X : 2014–2020
  • Sportster 1200 Iron XL1200NS : 2018–2020
  • Sportster 1200 Roadster XL1200CX : 2016–2020
  • Sportster 1200 Seventy Two XL1200V : 2014–2016
  • Sportster 1200 SuperLow XL1200T : 2014–2017
  • Sportster 883 Iron XL883N : 2014–2020
  • Sportster 883 Roadster XL883R : 2014–2015
  • Sportster 883 SuperLow XL883L : 2014–2020
Customer Reviews

Customer Reviews for ThunderMax ECM With Auto Tune Closed Loop System

Overall Rating

5 out of 5 stars (based on 32 reviews)

5 stars (28)

4 stars (4)

3 stars (0)

2 stars (0)

1 star (0)

0 stars (0)

BILLY on 12/20/2019

Quality and install is great still trying to find a tune that matches my set up

CAMERON on 10/14/2019

I was having misfiring issues and loss of power at low RPM with my bike for years. I took it to Harley and they said it was fine, then I took it to another shop who knew it wasn't right but couldn't find the problem. I read that there are issues with some stock ECM's. The ThunderMax was the best investment to replace my stock ECM and customize my tune. It runs like a new bike!

JACOB on 9/5/2019

easy to install and load base map haven’t got bike in a day I yet but tuning software is easy to use but could be set up a little better

Swifty67 on 7/22/2019

Easy to install and easy to get started with

WES on 6/17/2019

The hardest part is finding the right tune. After that you HAVE TO CONNECT to the computer after riding it a few hundred miles and set the learned as the base. After you shut off the bike it goes back to the base tune and relearns the fuel air ratio. I’m getting great mileage with this new computer and have good power.

TROY on 6/3/2019

It fit like OEM on my bike. I have yet to use the tuning feature. A little pricey but worth it. Program was easy to download and use.

AARON on 5/23/2019

Spend the money. Nothing else compares.

RICHARD on 5/7/2019

So far so good?? More money than I wanted to spend but I really like the auto tune. Installed and tuned it all myself.... can't say that it didn't make me nervous, but it runs great!

TERRY on 5/5/2019

Great purchase and straight forward hookup. TMax tech was great to work with and helped find the perfect map.

ROBERT on 4/15/2019

Installation and set up was very easy. So far it is working great. I look forward to learning and using the system to improve performance in the future.

Important Product Notes

Not legal for sale or operation in the state of California. Check with the U.S. EPA and your respective state and local regulations to confirm emission compliance. This item cannot be returned once the package is opened. Manufacturing defects must be addressed through the manufacturer directly.

Shipping Note

Due to state regulations we cannot ship this item to the state of California.

Pickup in our Retail Stores
Out of Stock in Retail Center Anamosa, IA
Out of Stock in Retail Center Daytona, FL
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