This article was adapted for drivers and tuning professionals in the United States by Viezu USA. Measurements are shown in US units alongside the originals.
Based on our recent VTA Academy webinar, this technical guide walks through the core steps of writing your own map pack in EVC WinOLS. Whether your ECU is a Bosch EDC17 C46 or a similar diesel unit, knowing how to find, label and convert raw data is the bedrock of professional remapping.
Why the Map Pack Comes First
A map pack is an organized set of identified maps inside an ECU's hex data. Without one, you're tuning blind. Automated software can help, but a pro tuner has to be able to dissect the ECU by hand to find the specific fueling, boost and torque tables.
Spotting Potential Maps
When you first import a project, WinOLS runs a background search for "Potential Maps," found through:
- Bosch Recognition: matching against known Bosch structures.
- Statistical Recognition: logic that flags data patterns resembling maps.
Pro tip: Sort potential maps by size. In ECU logic, the biggest maps (20×20, for example) usually matter most, because they span the widest range of RPM and load points. Smaller maps tend to handle specific corrections or limp-mode strategies.
Must-Have Maps for a Stage 1 Diesel Tune
For a working Stage 1 map pack, find these maps and move them from "Potential" into "My Maps":
1. Driver's Wish (Torque Request)
Turns the driver's throttle input into a torque request.
- Axes: throttle position (TPS %) vs engine speed (RPM).
- Logic: higher values at low RPM, tapering off as the engine nears its limit.
2. Torque Limiter
The gatekeeper. It sets the maximum torque the engine may produce, protecting the drivetrain.
- Axes: usually RPM vs atmospheric pressure.
- Shape: a classic torque curve that climbs steeply, peaks, then falls away.
3. Injection Duration (Pulse Width)
Tells the injector how long to stay open; the ECU uses it as a calibration lookup table.
- Axes: rail pressure vs fuel quantity (IQ).
- Logic: the higher the rail pressure, the less time it takes to inject the same amount of fuel.
4. Start of Injection (SOI)
Sets the crank angle where injection begins.
- Sign function: SOI maps in WinOLS often need the Sign Function turned on to show negative values properly (degrees before or after top dead center).
5. Boost Pressure and Limiters
Defines the target turbo pressure and the ceiling that prevents overboost.
- Axes: RPM vs fuel quantity.
- Conversion: Bosch ECUs usually show raw millibar (e.g., 2300 mbar = 1.3 bar of boost, about 19 psi, plus 1 bar atmospheric).
Conversions and Factors
Raw hex is rarely human-readable. To make it tunable, apply conversion factors. Common Bosch ones:
- Torque: 0.1 (a value of 3200 becomes 320 Nm / 236 lb-ft).
- Fuel (IQ): 0.01 or 0.1, depending on ECU generation.
- RPM: 0.5 (typical on Bosch EDC17).
- TPS %: 81.92 (derived from 8-bit/16-bit bit rates).
WinOLS FAQs
Is fuel measured in mm3 (volume) or mg/str (mass)?
For Stage 1, it hardly matters because the numbers are so close. For Stage 3+ custom builds with bigger injectors, check a Damos or A2L file to confirm the exact unit.
Can WinOLS find DTC tables on its own?
No. DTC removal is advanced work involving individual data bytes and related "error class" data elsewhere in the ECU. Beginners shouldn't just zero out codes without understanding the logic.
What's the fastest way to build map packs for similar ECUs?
Save the configuration once you've defined a map. WinOLS lets you propagate, or transfer, map properties to similar files, which dramatically speeds up development on future vehicles.
What is WinOLS?
Professional software built specifically to modify the memory contents of ECUs. Unlike plug-and-play tools, it lets tuners dig into the raw hexadecimal data to find, name and edit maps for things like turbo pressure, fuel injection and torque limits. It's widely regarded as the most advanced tuning editor around.
How does WinOLS connect to an ECU?
It doesn't: WinOLS is editing software, not a read/write tool. You use separate hardware (such as Alientech KESS3) to read the file from the vehicle, import it into WinOLS to edit, then use the hardware again to write the modified file back.
What does WinOLS cost?
It depends on the version and any extra modules or credits you need. Options include the WinOLS 5 full version and an annual WinOLS subscription. Add-ons such as checksum plugins or "Super Mappacks" can add anything from a small fee to a significant extra cost. Contact us for current US pricing.
Is WinOLS legal to use?
WinOLS itself is legitimate proprietary software developed by EVC Electronic in Germany. But:
- Licensing: buy it through authorized distributors. Cracked or torrented copies are illegal and a serious security risk.
- Usage: whether a given tune is allowed depends on the emissions and road safety laws where you are (see the US emissions note below).
Can WinOLS damage my ECU?
The software won't, but user mistakes can.
- Bad data: writing wrong values (too much boost, for example) can cause mechanical engine failure.
- Checksum errors: if you modify a file without correcting the checksum (a mathematical safety check), the car may not start or the ECU could be bricked.
- Clone tools: writing WinOLS files back with fake or cloned hardware is a major cause of ECU damage.
Can I reprogram my own ECU?
Technically yes, but it's a professional sandbox with a steep learning curve. As Simon put it in the webinar, diving in untrained is "a world of hurt," given the math and conversion factors needed to make raw data readable. Proper training, like the VTA Remap 101 Academy, is strongly recommended before you write your own files.
About the Author
Simon White is Viezu's Technical and Managing Director. Focused on research and development, he keeps up with the newest tuning tools, software and techniques. An experienced tuner with EVC Platinum trainer status, he delivers vehicle tuning training courses worldwide for the Viezu Technical Academy.
US emissions compliance note
In the United States, modifying, removing or disabling emissions-control equipment (including DPF*, EGR*, SCR*/DEF* and catalytic converter systems) on a vehicle used on public roads may violate the federal Clean Air Act and EPA rules, and in California and other states that follow CARB standards, additional restrictions apply. Any off-road, race or competition-only modification described here is not intended for street use. Nothing in this article claims that any product or calibration is EPA- or CARB-certified or street legal. For guidance on options for your vehicle, contact Viezu USA.
US note: Performance modifications can affect your auto insurance. Tell your insurer about any ECU tune or modification before driving on public roads.
Talk to Viezu USA
Want to know what Viezu can do for your vehicle or your business? Request a performance upgrade quote, browse viezuusa.com or contact the Viezu USA team.
* EMISSIONS TAMPERING WARNING
Removing, disabling, deleting, or rendering inoperative any emissions control device or system (including DPF, EGR, SCR/DEF, catalytic converters, and related sensors or software) on a vehicle used on public roads is prohibited under the U.S. Clean Air Act and may also violate state laws, including California Air Resources Board (CARB) regulations. Violations can carry substantial civil penalties for vehicle owners, installers, and sellers.
Any reference in this article to DPF, EGR, SCR, or other emissions-related functions is provided for informational purposes and, where applicable, for closed-course competition or off-road use only where permitted by law. Viezu USA does not condone emissions tampering on any road-going vehicle. It is the customer's sole responsibility to ensure that any modification complies with all applicable federal, state, and local laws, regulations, and policies, regardless of what country you live in.