The s300 version 3 is a plug in module to the OBD1 factory Honda Engine Computer (not
vastly expands the capabilities of the factory ECU. Forced induction,
datalogging, real time programming, Bluetooth and engine protection are but a few
of the comprehensive s300 features.
Designed, manufactured and assembled in the USA.
Note that there is a rectangular frame ECU version of the s300 and a square
frame ECU version (s300J). Available now.
Counterfeit and on-line auction site warning
It has come to our attention that counterfeit s300's -
green circuit board Version 1 are being sold as new and
used. Protect yourself from purchasing a
Do not purchase new Hondata items from online
auction sites such as E-Bay. There is a high risk of being
scammed or being sold a counterfeit. Hondata dealers do not sell
through on-line auction sites. Do not purchase from
Sehablaauction / PrecisionProposition.
s300/s300j Price, Availability and Options
s300/s300j Real time programmable circuit
Upgrade from older s300 to the new s300 V3 (use this
Upgrade from an older system - s100/s200 to s300/s300j Use this form
S300J available June 1
Sold separately, these are two great add-ons for the S300:
High and low speed 24 x 20 ignition and fuel tables for correct VTEC tuning
Injector size fuel trim
Fuel trim for starting, throttle tip in and individual cylinder trim
Rev limiter with fuel cut or fuel and ignition cut
Launch control with anti-lag
Full throttle shift
Adjustable VTEC window with load and throttle control
Secondary intake runner control
Adjustable idle speed
Adjustable boost cut with hot and cold settings
Closed loop control
Air temperature compensation
Water temperature compensation
Fuel and ignition correction based on gear
A/C shutoff conditions
Three general purpose outputs for nitrous control, quad boost control or
The s300 can be updated in real-time with the engine running without affecting the operation of the vehicle. This means that calibrations and changes can be uploaded to the ECU very quickly (2 seconds for a new calibration, a fraction of a second for anything else), without interrupting the operation of the engine. Changes made in the
SManager software are uploaded to the ECU instantly and you can see the effect immediately. The s300 does not use an EEPROM
or equivalent, so you never need to open the ECU to change chips nor 'burn'
ROMs. No EPROM programmer is necessary - you just need a laptop with USB port or
Radio technology capability.
The s300 has datalogging to the SManager software built in via the USB or
Using a laptop or mobile device the various ECU sensors can be data-logged, viewed, graphed and
saved for later analysis.
Additionally the s300 has on board flash memory which allows a datalog to be made without a laptop, for later access and download. Multiple recordings can be made and stored in the s300 for a total
of around 120 minutes of total datalogging time. An external switch can be
used to start and stop recordings, or engine conditions can trigger recording. For instance in a drag race, the s300 can be set to start recording once the rpm
is bought up to near launch rpm and automatically stop once past the traps and
the rpm drops below a certain level.
Details on preparing the ECU can be found
here. It is
strongly recommended that you have this professionally installed. If the ECU has been previously socketed
you run a high risk of damaging the ECU (lifting tracks or burning
s300j Specific Notes
PCS output is not present on the JDM ECUs and cannot be used for nitrous
controls. All other inputs and outputs are present and can be used for
nitrous controls. Boost control uses a different output pin on the JDM ECU.