Tune, flash, and diagnose your Subaru ECU

RomRaider, EcuFlash, and your own custom definitions are independently enabled with a configurable priority “main” source. Malformed or incomplete definitions show up as warnings in-app instead of silently vanishing.

A Definitions page that finds which tables exist for a ROM — identified automatically from its own ID bytes, or typed in — and shows how many were found and any parse warnings. The tables then appear in the sidebar tree, grouped by category, and the hex editor can add a selection of bytes to the definition as a new table.

Every selected parameter is drawn as a line graph over time (a rolling window you can zoom), next to the gauge tiles. Each run is kept as its own session that can be saved and loaded again, and recorded to CSV.

Connect to the FastECU J2534 adapter, including its wireless (WiFi) version, set its WiFi password and update its firmware, all from Settings.

A protocol’s transport, connect sequence, kernel and ROM layout, with its security-access and checksum definitions, can be described in a script and edited in Settings. If you want to add a protocol the app doesn’t have, you can write a script for it — a new protocol variant can be a script, not new code.

An optional local MCP server, off until you switch it on, lets an AI assistant read the open ROM, its tables and your datalogs and propose edits. You review every proposed cell before and after, and apply, reject or undo it — the assistant never changes a ROM itself. (Not in the Windows 7 build.)

FastECU checks for a new version when it starts and installs it with one click. Every update is signed with FastECU’s release key, so a swapped file is never installed. Switch to the Beta track in Settings to get test builds before they are released to everyone. Help → About shows the version, platform and build details to copy into a support message.

Windows 10 and later, Windows 7 / 8 (a separate 32-bit build) and a Linux AppImage, each updating itself. The theme is dark, light or follows the system.

Every change to a ROM — from a table window, the hex editor or a reviewed proposal — can be undone and redone. A Changes panel lists the tables changed since the ROM was opened, each one revertable, with named snapshots to go back to. Your changes can be saved as a small tune file without the ROM and applied to another ROM, also to another version of the calibration.

Two ROMs compared table by table, each read with its own definition, with the changed cells and the difference shown. A definition can be carried over to another version of the same calibration: the app finds where each table went and writes the new definition, marking the tables to check by hand.

A map finder finds calibration tables the definition is missing by their shape and adds them with a click. A definition check lists what is probably wrong with a definition against its ROM. The hex editor shows the whole ROM as a strip of code, data, erased and text areas with the tables and checksum ranges marked.

Checks a loaded ROM’s checksums and fixes them as an edit you can undo, for every ECU family the app knows; checksums of your own can be described too.

A table shown as a surface you can turn and zoom, with cells that stand out from their neighbours marked in the view and the grid.

Look at the code in a ROM: M32R (Hitachi, Unisia Jecs), SH-2 / SH-2A (Denso, Hitachi DIT) and HC16. The whole ROM is listed with its functions, labels and cross-references, a function can be read as C, and its control flow shown as a chart. The CPU is recognised from the ROM itself. Disassembler projects keep their own copies of the ROMs. (Not in the Windows 7 build.)

Math channels — formulas over logged values, such as boost, lambda or injector duty — drawn as their own lanes; full-throttle pulls found and outlined; notes pinned to moments; a second run drawn over the first; every value at the cursor. Recording can be set to write a file only while a condition holds, with seconds before and after it. Built, not yet tried with a real log.

A table window shows where the car was in it: the current cell, how often each cell was hit, or the mean of any logged value per cell. From that it proposes a per-cell correction you review: timing out where knock pulled it, fuel where the wideband read lean or rich against the target AFR, and wastegate duty where boost stayed under or went over its target. Built, not yet tried with a real log.

Target against actual boost for every full-throttle pull of a log — peak, overshoot, the engine speed where it reached the target and the error after — and per engine speed band, with the wastegate duty it took. Built, not yet tried with a real log.

Corrects the MAF Sensor Scaling curve from fuel trims (closed loop) and the A/F sensor against the target AFR (open loop), shows it against the curve in the ROM, and proposes it as an edit you review. Built, not yet tried with a real log.

Sniffs a CAN or K-Line bus through the adapter, decodes SSM, UDS and KWP messages, lights up the bytes that change per id, and sends messages by hand. Built, not yet tried on a car.

The original also works through a broker; NextGen adds pairing with a short code, so there is no address to type, and a relay run by FastECU. Someone else — with FastECU or the small FastECU Remote Client — works with the ECU connected to your adapter over the internet, end-to-end encrypted through a relay that only forwards bytes. Built; the relay run by FastECU is still being set up.

Fits the Injector Flow Scaling and Injector Latency of the loaded ROM from a datalog, shows them against the ROM’s values and proposes the change as an edit you review. The tab can start a log of just the values it needs. Built, not yet tried with a real log.

Power and torque curves from full-throttle pulls in a datalog of a manual car, from the car’s weight, drag and rolling resistance entered once and saved per car. Built, not yet tried with a real log.