WinOLS Guide (5/10): Scripts, Checksums, Comparison & Workflow Tips

Editing maps is only half the job of professional ECU tuning. The other half — the half that separates a reliable, efficient operation from a chaotic one — is workflow. Checksum correction, file comparison, scripted automation, version management, and disciplined project organisation are the tools that let you work faster, make fewer mistakes, and build on your own experience over time. This guide covers every major WinOLS productivity feature in depth.

Checksums — Why They Exist and How They Work

Every ECU binary contains one or more checksum values — mathematical signatures calculated across specific blocks of calibration data. Each time the ECU boots, it recalculates these signatures and compares them against the stored values. If even a single byte in the covered region has changed, the recalculated checksum will not match the stored value, and the ECU will either reject the file, log a fault code, or enter limp mode.

The algorithms vary by ECU family. Common types include:

• Simple additive sums — all bytes in a region added together; the result stored as an 8-bit, 16-bit, or 32-bit value
• CRC-32 — a polynomial-based cyclic redundancy check that is highly sensitive to any change in the data
• XOR checksums — all bytes XORed together, producing a single value
• Proprietary algorithms — some manufacturers (notably Siemens/Continental) use custom algorithms that are not publicly documented

Many ECUs use multiple checksums covering different memory regions. A Bosch EDC17, for example, may have separate checksums for the calibration area, the program code area, and the driver software area. Changing a map in the calibration region only invalidates the calibration checksum, but you still must correct it before flashing.

WinOLS Checksum Correction

WinOLS includes a built-in checksum correction module with support for hundreds of ECU types. The process is straightforward:

1. Complete all your map editing work first.
2. Go to Misc → Checksum correction (or click the checksum button on the toolbar).
3. WinOLS identifies the ECU type automatically from the binary content, or you select the correct type manually from a list.
4. The software recalculates every checksum based on your modified data.
5. The correct values are patched into the addresses where the checksums are stored.
6. A log window displays which checksums were updated and shows both old and new values.

Critical rule: Always run checksum correction as the very last step before exporting the binary. Any edit made after checksum correction will invalidate the checksums again, and you will need to re-run the correction. Never manually edit bytes at checksum addresses unless you fully understand the algorithm — an incorrect checksum can cause a non-start condition that requires recovery flashing.

When Built-In Correction Fails

Not every ECU type is supported by WinOLS’s native module. When the built-in correction does not recognise your file or reports zero corrections on a file you know was modified, you have several options:

• Third-party checksum plugins — available from EVC (the makers of WinOLS) and from the tuning community. These install as plugins within WinOLS and extend the supported ECU list. EVC also offers a Checksum Dongle — a hardware device that provides checksum correction for additional ECU types not covered by software plugins.
• External checksum tools — standalone applications that process the binary file outside WinOLS. You export your modified .bin, run it through the external tool, and re-import the corrected file.
• Manual checksum calculation — for rare or exotic ECUs where no automated solution exists, you can sometimes identify the checksum algorithm by analysing the ECU’s disassembled code, then calculate the correct value manually or write a small script to do it. This is advanced work reserved for ECUs where no other option is available.

Project Comparison — Detailed Walkthrough

Comparing two versions of an ECU file is one of the most powerful capabilities in WinOLS. It is essential for learning, quality assurance, and reverse-engineering tuned files. Here is the full workflow:

1. Open the stock file as a project (or open your modified project — whichever you want as the “base”).
2. Go to Version → Import version from BIN and load the second file (e.g., the tuned file). This adds it as a new version within the same project.
3. Press Ctrl+D to toggle difference highlighting. Changed bytes now appear in colour in the hex view.
4. Navigate between differences using F7 (next difference) and F8 (previous difference). WinOLS jumps the cursor directly to the next address where the two versions differ.
5. Interpret what you see:
   • Large contiguous blocks of changes — these are map modifications. The block size and location correspond to a specific map table.
   • Small scattered changes (typically 2–4 bytes at isolated addresses) — these are almost always checksum values that were recalculated after the map edits.
   • Single byte changes — often flags or switches (e.g., a DPF enable/disable bit, a speed limiter toggle, or a feature activation byte).

When you view an identified map with a comparison loaded, WinOLS shows both versions overlaid in the 2D or 3D view, making it immediately clear which cells were changed and by exactly how much. This is the fastest way to reverse-engineer someone else’s tune and understand their approach.

Scripts — The Power User Tool

What Scripts Are

A WinOLS script is a recorded sequence of map modifications that can be saved and replayed on different files. Think of it as a recipe: instead of manually editing a map cell by cell each time, you record the changes once and apply them with a single action on future projects.

How to Create a Script

1. Open the map you want to modify.
2. Press F8 to start recording (the status bar indicates recording is active).
3. Make your edits — select cells, apply percentage changes, add or subtract values.
4. Press F8 again to stop recording.
5. Save the script with a clear, descriptive name (e.g., “Stage1_Boost_Target_plus15pct”).

Script Types

WinOLS supports three fundamental script operation modes:

• Absolute — set cells to a fixed value X. Useful for limiters or switches where the target value is always the same.
• Difference — add or subtract a fixed amount Y from existing cell values. Useful for timing adjustments (e.g., “add 3° to all cells”).
• Percentage — multiply existing cell values by Z%. Useful for boost and injection quantity changes where a proportional increase is more appropriate than a fixed offset.

Use Cases

• Batch processing — tune 50 identical vehicles with the same ECU software version by applying the same script set to each file.
• Standardised tuning stages — define your Stage 1, Stage 2, and custom recipes as script sets for each common ECU type, ensuring consistency across all jobs.
• Training and handover — share scripts with new team members so they can produce consistent results while learning.

Critical limitation: Scripts reference specific map addresses and dimensions. They only work correctly on files with the same internal structure — meaning the same ECU software version. Applying a script to a different software version where maps have shifted addresses will modify the wrong data. Always verify results visually after applying a script to any file.

Version Management

WinOLS includes a built-in version system that stores labelled snapshots of the entire binary within the .ols project file. Effective version management is your safety net against editing mistakes and your record of how a tune was developed.

Best Practice Naming Convention

Create a version snapshot before every significant editing session. Use a consistent naming scheme:

• v0_stock — always create this immediately after importing the original binary, before any edits
• v1_stage1_boost — after increasing boost targets
• v2_stage1_timing — after adjusting ignition or injection timing
• v3_stage1_final — the completed tune before checksum correction
• v4_stage1_checksum — the final version with corrected checksums, ready for export

To roll back, go to Project → Version → Select version and choose any previous snapshot. WinOLS restores the binary to that exact state. You can then branch off in a different direction without losing the work recorded in other versions.

Professional Workflow

Project Organisation

Organise your file system by manufacturer, then model/ECU combination:

/Tuning_Projects
  /BMW
    /F30_320d_B47_EDC17C50
      /Customer_Jobs
      /Reference_Files
      /Mappacks
  /VW
    /Golf7_2.0TDI_CUNA_EDC17C74
      /Customer_Jobs
      /Reference_Files
      /Mappacks

Use descriptive file names: 20260415_BMW320d_Stage1_KM12345.ols for customer jobs, EDC17C50_B47_v3.kp for mappacks, and B47_8xxxx_stock.bin for reference originals.

Backup Strategy

Keep untouched original .bin files in a read-only archive folder. Back up your entire WinOLS project directory to both an external drive and cloud storage. A corrupted .ols file means losing all versions and editing history for that project. Export critical final versions as standalone .bin files for portability.

Working with Multiple Monitors

WinOLS supports detaching map views into separate windows. On a dual-monitor setup, keep the map list and hex view on one screen and the active 2D/3D map view on the other. When doing comparison work, place the stock map view on one monitor and the modified version on the other for side-by-side analysis.

Template Projects

For ECU types you work on frequently, maintain a “template project” — a clean .ols file with all maps identified, axes configured, and categories assigned, but with stock calibration data. When a new customer file arrives for the same ECU type, import the customer’s binary into the template project to instantly inherit all map definitions without re-applying a mappack.

Complete Keyboard Shortcuts Reference

Pro tip: Ctrl+M (multiply) is the shortcut you will use most often. Select a range of cells, press Ctrl+M, enter a multiplier (e.g., 1.15 for +15%, or 0.90 for −10%), and confirm. This is faster and more consistent than editing cells individually, and it preserves the relative shape of the map curve.

Next in the Series

WinOLS Guide (6/10): Writing Your Own WinOLS Mappacks will teach you how to create, export, and share your own mappack files — the reusable map definition templates that eliminate hours of manual identification work on every project. Stay tuned.

If you don’t have the time or expertise to tune files yourself, upload your original ECU file to fileservice24.at and receive your professionally modified file in about 60 seconds.