What TGVs and their sensors do
Tumble generator valves, or TGVs, are flaps built into the lower part of the intake manifold on many Subaru engines. They change how air enters the cylinder, adding swirl to help combustion in certain conditions such as a cold engine at closed throttle. Each side of the engine has its own valve, and each valve has a position sensor so the ECU can confirm whether the flap is open or closed.
The Elite's TGV Sensor 1 and 2 functions read those two sensors. That means you can log the valve positions, see them on your ESP pages and flag a fault if a sensor or its wiring fails.
Plenty of Subaru builds remove the TGVs or fit a manifold without them. If there's nothing to read, leave these inputs unassigned and keep the diagnostics disabled so you don't log false codes.
Wiring tab
Assign Tumble Generator Valve 1 Input and Tumble Generator Valve 2 Input. Each should go to an AVI if you have enough free. An SPI can be used when you don't.
| Setting | What it does | Our advice |
|---|---|---|
| AVI Pull up | Connects a 1k resistor from the input to 5V | Off for a position sensor with its own 5V supply |
| SPI Sensor Type | Tells the SPI how to read the signal | Hall Effect when an SPI is reading an analog sensor |
| SPI Pull up | Connects a weak 10k resistor to 5V | Off for a powered sensor, same as the AVI |
Pullups exist for two-wire sensors that rely on the ECU to supply their voltage, such as typical temperature senders. Sensors with their own supply don't want one. On a piggyback setup, where the factory ECU still reads the same sensor, that ECU generally supplies the pullup already, so leave the Haltech's disabled.
Calibration tab
ESP includes pre-loaded calibrations you can choose from. If yours isn't listed, create one from the sensor maker's voltage data. The yellow Open icon loads a calibration file and the blue disk icon saves your own for later. Before trusting any calibration, operate the valves and watch the live readings move between the open and closed positions you expect.
Display tab
Warning Maximum is the voltage above which TGV readouts in ESP flash red as a high-voltage warning. Set it just above the highest voltage a healthy sensor produces, which you can read in live data with the valve at its end of travel.
Diagnostics tab
These limits catch wiring faults. Both are disabled by default. With Engine Protection running you can also assign a DTC severity to each.
| Setting | Code | Sets when | Points to |
|---|---|---|---|
| Raw Min | P1354 | Sensor voltage drops below your limit | Open signal wire or a short to ground |
| Raw Max | P1355 | Sensor voltage rises above your limit | Short to supply or a lost sensor ground |
Put both limits a little outside the voltages you see across full valve travel, so real movement never trips them but a broken wire does.
Troubleshooting
| Symptom | Usually |
|---|---|
| Reading stuck near 5V | Pullup on with a powered sensor, or an open signal wire |
| Reading stuck near 0V | No 5V supply to the sensor, or signal shorted to ground |
| Reading changes but open/closed looks wrong | Calibration doesn't match the sensor |
| Codes logged on a car without TGVs | Inputs or diagnostics left enabled after a TGV delete |
Running a Nexus ECU? See tumble generator valve for the NSP version. Other Elite sensor setups follow the same pattern, for example the throttle position sensor.
