What TGVs are, and why you'd monitor them
Tumble generator valves (TGVs) are flaps in the lower part of the intake manifold on many Subaru engines. The factory system moves them depending on engine temperature and throttle, mainly around cold start and warm-up, to change how air tumbles into the cylinders. Each valve has a position sensor so the ECU can tell whether it is open or closed.
In NSP, the Tumble Generator Valve sensor channel reads those sensors. Monitoring them is how you find out that a valve has stuck, or that a sensor or its wiring has failed, before it shows up as a strange running problem.
Setting up the channel
Calibration
On the main TGV sensor node, either load a ready-made calibration or enter one by hand. If you're entering it yourself, measure the sensor voltage with the valve fully open and fully closed and use those as your end points.
Display
This node sets how the TGV channel appears on screen. The key setting is Warning Maximum: the voltage above which number displays, gauges and bars for the TGV sensor switch to their upper warning state. Set it just above the highest voltage a healthy sensor produces, so a warning means something has actually changed.
Diagnostics
Here you can enable DTCs for high and low sensor voltage. Each has its own severity, and that severity links to an engine protection level. A sensor reading outside its normal range almost always means an open circuit, a short or a failed sensor, so these DTCs are cheap insurance. See engine protection for how severity levels act.
Wiring
TGV sensors are analog, so they connect to an AVI. Any free AVI will do; select it on this node. Power the sensor from the ECU's 5 V supply and ground it to sensor ground, not chassis ground.
Our advice
- Start with a mild severity level until you've watched the sensors through a few cold starts and know what normal looks like.
- If you've removed or blocked off the TGVs, don't enable their diagnostics. A disconnected sensor will just set constant codes.
- On an Elite ECU, the equivalent setup is in TGV sensor 1 and 2.
If you're fitting a Nexus to a Subaru, the Nexus S3 plug-in adapter kit for the WRX MY06-10 is one of several Subaru options we stock. Not sure which suits your car? Ask us.
