Autotuning the Apexi PFC – New Product I'm building

The Development:

At First, I used an Arduino uno to establish a serial/uart connection into the PFC. This was the first milestone. I was going in pretty blind but was able to establish a connection and was relatively quickly able to view the realtime data, though didn’t yet have everything parsed. I was viewing the data through the serial console in Arduino.

Next up, I added a screen and was able to output some of the data in real time. First was the RPM and wheel speed, and then I was able to wire in the WB02, view knock levels, etc. 

I then purchased a screen, rotary knob and button combo and got it all wired in. I was then able to view a few more items and began creating a menu system. At this point I had established that I was able to parse almost all of the “Live” data from the PFC, but the next big step was getting a board that had enough power and the features to actually make this worthwile. At this point I purchased the Teensy 4.1 board(without ethernet).

I also purchased a few other things to build out something that looked somewhat usable instead of just a bunch of hacked together boards. I also had to start designing how it would be layed out. It introduced the first few potential issues. First, the Teensy runs on 3.3v and is not tolerant to 5v like the arduino is. The PFC has four wires for it’s output, VCC which is 5v, TX, RX and Ground. The RX line is also 5V, so I had to add a voltage stepdown using a few resisters. I also added a 1k resistor on the TX line to help alleviate some potential noise; more of a safety than anything. 

Slowly got everything connected and the screen wired up and had the controller functional(though not fully programmed yet). 

Screen on and working. Powered by computer USB still. 

At this point, the big programming has started. I also got very tired of having to run back and forth to/from my car, so I pulled the PFC and powered it externally to run on my test bench(technically just from my couch, but i digress). Progress is being made. 

# PowerFC Gauges & AutoTune Bridge Overview

## Purpose

PowerFC Bridge is a companion display and tuning assistant for the Apexi PowerFC. It is designed to show live engine data, help confirm the car is ready for tuning, back up map data, and support fuel and ignition tuning workflows.

The current focus is Toyota PowerFC support, with the project structured so other PowerFC platforms can be added later.

## What It Does

– Displays live PowerFC data such as RPM, speed, AFR, knock, coolant temperature, intake temperature, and boost when enabled.
– Reads and backs up PowerFC map data to the SD card in an FCEdit-compatible format.
– Loads the injector correction map as the expected AFR target map.
– Supports wideband oxygen sensor input through the Teensy analog input.
– Provides readiness checks before allowing fuel or ignition tuning.
– Supports fuel logging, safe fuel autotune, and live fuel autotune modes.
– Provides ignition autotune controls and ignition advance controls for future tuning logic.
– Saves settings to the SD card so configuration can persist between sessions.

## Controls

The interface uses three physical buttons plus the rotary encoder.

– Confirm button: moves forward through pages.
– Back button: moves backward through pages, or cancels confirmation prompts.
– Rotary knob: scrolls through selectable items on the current page.
– Rotary button: toggles or activates the selected item.

## Startup

On startup the screen shows:

“`
PowerFC Gauges & AutoTune
Waiting for connection…
“`

Once valid PowerFC data is received, the display moves into the normal page flow.

## Main Pages

### 1. Gauges

The Gauges page is the primary driving display.

It shows:

– Large RPM display.
– Speed.
– Current AFR.
– Expected AFR, only when O2 feedback is disabled and a valid AFR map is loaded.
– Knock value.
– Autotune status.
– Boost, when enabled in settings.
– Engine coolant temperature.
– Intake air temperature.

This page is intended for quick viewing while driving or testing.

### 2. Readiness Checks

The Readiness Checks page shows whether the system is ready for tuning or logging.

Current checks include:

– Water temperature: must be at operating temperature(Greater than 160f)
– Map backup: confirms the relevant maps have been backed up.
– O2 feedback: must be disabled for tuning.
– AFR map: must be loaded from valid injector correction map data.

Fuel and ignition tuning are locked out when required checks are not met.

### 3. Fuel AutoTune

The Fuel AutoTune page controls fuel-related tuning and logging.

Options:

– Start Live Auto Tune / Stop Live Auto Tune.
– Start Safe Auto Tune / Stop Safe Auto Tuning.
– Start Logging / Stop Logging.

Starting either fuel autotune mode disables O2 feedback. This is intentional because the PowerFC O2 feedback system would otherwise interfere with wideband-based tuning corrections.

Live Auto Tune is intended to update the running PowerFC maps directly once enough valid samples are collected. This should only be used once write behavior is fully validated.

Safe Auto Tune updates a working tune file on the SD card instead of directly changing the running ECU map. This allows the generated map to be reviewed in FCEdit or similar tools before being written manually.

Logging records AFR samples by load cell for later review.

### 4. Ignition AutoTune

The Ignition AutoTune page is dedicated to ignition tuning controls.

It displays:

– Current ignition angle.
– Knock value.
– Ignition autotune status.
– Ignition advance enable status.

Ignition tuning requires the required checks to be met before it can be enabled.

### 5. Sensor Data

The Sensor Data page is a more detailed live-data view.

It is intended for checking raw or supporting values such as:

– Speed.
– RPM.
– AFR.
– Coolant temperature.
– Intake temperature.
– Knock.
– Battery voltage.
– O2 feedback state.

This page is useful during setup, troubleshooting, and sensor validation.

### 6. Settings

The Settings page is used for configuration and storage actions.

Common settings and actions include:

– Enable or disable O2 feedback.
– Back up maps.
– Save or load settings.
– Load the AFR map.
– Format the memory card.
– Enable or disable boost display.

The Settings title area displays short status messages while actions are running, such as backing up maps, backup complete, loading settings, or loading the AFR map.

### 7. WB02 Type

The WB02 page selects the wideband oxygen sensor calibration.

Current options:

– Innovate.
– AEM.
– Custom file.

Innovate is the default. For custom wideband support, the SD card includes a placeholder calibration file that can be edited with the sensor’s 0-5V AFR range.

The custom wideband example file is:

“`text
/PFC/custom_wb02.txt
“`

Example contents:

“`text
# Custom wideband 0-5V linear calibration
# Edit these AFR endpoints to match your controller.
# Example: 0V=8.0 and 5V=22.0
0V=8.0
5V=22.0
“`

## Readiness Checks

The tuning and logging checks are intended to prevent collecting bad data or making corrections under unsafe conditions.

Required conditions include:

– Coolant temperature above operating threshold.
– Wideband O2 actively reading.
– O2 feedback disabled.
– Required maps backed up.
– Valid injector correction map loaded as the AFR target map.

Autotune and logging can be enabled at 0% throttle and below the minimum road-speed threshold. Samples are only collected once speed and throttle are both above the sampling thresholds, currently 16 km/h and 3% throttle, so idle or stationary data does not affect the tune.

Fuel tuning also requires:

– Base fuel map loaded.
– Injector correction map loaded and converted into valid AFR targets.

Ignition tuning also requires:

– Ignition map backed up.

## AFR Target Map

The expected AFR map comes from the injector correction maps:

“`text
inj_86
inj_87
inj_88
inj_89
“`

These maps are converted into target AFR values. If the injector correction maps are missing, incomplete, or invalid, fuel autotune is disabled.

There is no default 14.7 AFR fallback. This avoids tuning against an assumed target that may not match the actual PowerFC map.

## Fuel Autotune Modes

### Live Auto Tune

Live Auto Tune collects AFR samples and is intended to write fuel map updates back to the PowerFC once enough samples are collected.

This mode should be treated carefully because it changes the running ECU map.

### Safe Auto Tune

Safe Auto Tune collects AFR samples and updates a working map file on the SD card.

This mode is intended for review-first tuning. The updated map can be opened in FCEdit or another tool before being written to the PowerFC.

### Logging

Fuel logging records AFR samples into a 20×20 map-shaped log. Each cell stores averaged AFR data for the load and RPM area where samples were collected.

Ignition or knock logging records the highest knock values seen in each load and RPM cell.

## SD Card Use

The SD card stores:

– Settings.
– Map backups.
– Versioned backups.
– Working map files.
– AFR logs.
– Knock logs.
– Wideband custom calibration files.

Map backups are saved in a format intended to remain compatible with FCEdit.

Starting fuel logging creates or refreshes the AFR log file immediately, even before enough throttle is applied to collect samples.

Avoid removing the SD card while a backup, save, load, format, or logging operation is active.

## Safety Notes

This device is intended as a tuning aid, not a replacement for careful calibration.

– Confirm wiring before powering the PowerFC or Teensy.
– Confirm wideband calibration before using AFR data.
– Back up maps before enabling tuning.
– Use Safe Auto Tune when validating new behavior.
– Review generated maps before writing them to the ECU.
– Do not tune while the engine is cold or the wideband is warming up.
– Treat knock data conservatively.

## Current Development Status

The project can display live data, read maps, back up compatible map files, load AFR targets from injector correction maps, and provide the UI structure for fuel and ignition tuning.

Fuel and ignition tuning logic is still being developed and should be validated carefully before direct live writing is used.

@pattielipp thanks for what you’re doing!

Hope you’ll have the greatest success on this project! 

Interested to buy when is fine. 

You find my pvt messages in messanger.

Raffaele 🖐️