How to Change the Save to AutoCal Number: A Complete Guide
AutoCal is a calibration and tuning software platform widely used in automotive performance tuning — particularly for saving, managing, and flashing calibration files (commonly called "tunes") to supported vehicle ECUs. One frequently misunderstood setting within AutoCal is the "Save To" number, which controls which calibration slot your tune file is written to on the device. Changing it incorrectly can cause confusion, overwrite files you wanted to keep, or send the wrong tune to your vehicle.
Here's what you need to know about how this number works, what affects it, and why the right answer varies by user.
What Is the "Save To" AutoCal Number?
When you use AutoCal (most commonly the EFILive AutoCal device), the device can store multiple calibration files in numbered slots. The "Save To" number defines which slot a tune file gets written into when it's pushed from the EFILive FlashScan/AutoCal software on your PC to the AutoCal device itself.
Think of it like numbered folders on a USB drive. Each slot holds a separate calibration file, and the number you assign tells the software exactly where to place it. If your device supports, say, eight slots, you're working with numbers 1 through 8. Saving to slot 3 means that tune lives in position 3 — and that's the one the vehicle's ECU will receive when slot 3 is selected during a flash.
This matters because many tuners and end-users store multiple calibration versions on a single AutoCal device — for example, tunes optimized for different fuel types, operating conditions, or vehicle configurations.
How to Change the Save To AutoCal Number
The process takes place inside the EFILive Tune software on your PC, before you write the file to the AutoCal device. The general workflow looks like this:
- Open EFILive Tune and load the calibration file you want to transfer.
- Navigate to the AutoCal write/save settings — typically found under the File menu or the AutoCal device management panel, depending on your software version.
- Locate the "Save To" field or dropdown. This is where the slot number is displayed and edited.
- Change the number to your desired slot (e.g., change from 1 to 2, or from 4 to 6).
- Proceed with writing the file to the AutoCal device as normal.
The exact menu path and UI layout can differ slightly between EFILive software versions, so if you're running an older build, the option may appear under a slightly different label or location within the interface.
Some users also encounter this setting when working with tune packages prepared by a remote tuner. In that case, the tuner may have pre-configured the slot number in the file — and you may need to change it if it conflicts with an existing file on your device that you don't want overwritten.
Variables That Affect How This Setting Works 🔧
Not everyone's experience with this setting is identical. Several factors shape how the "Save To" number behaves in practice:
| Variable | Why It Matters |
|---|---|
| AutoCal hardware version | Different device generations may support different numbers of available slots |
| EFILive software version | UI layout and menu paths shift between major and minor releases |
| Number of tunes already stored | Existing files in slots can be overwritten if the number isn't checked first |
| Tuner-configured files | Remote tunes may have slot numbers pre-assigned that need manual adjustment |
| Vehicle/ECU type | Some ECU configurations use specific slot conventions by tuner preference |
If you're using a dealer-level or professional AutoCal setup, your device may be locked or managed differently than a standard end-user device, which can restrict which slots are available for editing.
Why the Slot Number Matters More Than It Seems
A common mistake is treating all slots as interchangeable backups. They're not always that simple. Some tuners deliberately assign specific tune types to specific numbers — for example:
- Slot 1: Base street tune (91 octane)
- Slot 2: Performance tune (93 octane or E85 blend)
- Slot 3: Tow/haul or conservative fuel economy tune
- Slot 4: Diagnostic or stock restore calibration
If you write over slot 4 with a modified tune without realizing it was your stock restore file, recovering your original calibration becomes a separate, more involved process. Keeping track of which number maps to which tune — and intentionally choosing where new files land — is the practical reason this setting deserves attention. 📁
The Spectrum of User Situations
How much this setting matters to you depends heavily on how you use AutoCal:
Single-tune users who only ever flash one calibration rarely need to think about this at all. Slot 1 works fine, nothing conflicts, and the number never needs changing.
Multi-tune users — those running different fuel types, seasonal tunes, or performance variants — need to actively manage slot assignments. For them, changing the "Save To" number before writing each file is a routine part of the workflow.
Remote tune customers receiving files from a tuner are often in the middle ground: they may receive files pre-configured for a specific slot, but their device already has something in that slot. Understanding how to check and change the number before writing prevents accidental overwrites.
Tuners building packages for clients deal with this at the highest level of complexity — assigning slot numbers deliberately across a full set of calibrations, ensuring no conflicts, and sometimes including documentation explaining which number corresponds to which driving scenario. 🎛️
The version of EFILive you're running, how your specific AutoCal device is provisioned, and the conventions your tuner uses all shape what "changing the Save To number" actually looks like in your specific situation — and whether doing so is a minor setting tweak or a step that requires careful coordination with whoever built your tune.