This article is about the Throttle Position Sensor on the throttle body, and why you may not need it at all.
The Throttle Position Sensor (TPS) is a sensor on the throttle body that tells megasquirt how open the throttle plate is. It tells the computer how much and how fast you are pushing the pedal.
- What is a TPS
- Where to get a TPS throttle body
- Wiring the TPS
- When not to use a TPS
- When to use a TPS
The Passat throttle body will only have a Throttle Position Sensor (TPS) on an AUTOMATIC car. Automatic G60 Corrados also have them. Some California-Emissions cars in the early 90s have them as well. If you do get a non-TPS throttle body from one of these cars, a new TPS can be added. But they aren’t cheap!
At right, you will see the proper way to wire the TPS on a VW throttle body.
Remember – by default, Megasquirt uses the TPS only for Acceleration Enrichment (AE). That means Megasquirt gives the engine more fuel when you put the pedal down for a quicker reaction. With MSnS-e, or Megasquirt II, you can use MAP based AE, which will use MAP vacuum readings to replace the TPS. This is slightly more accurate, and much simpler to do.
If you use ITBs, then you cannot get accurate vacuum readings from the throttle bodies, even if you tie them together with a small plenum. In this case, you do not have to hook up the Megasquirt vacuum line at all. Instead, set the Megasquirt to Alpha-N fueling equation, and use the ITB’s built-in TPS to take care of everything.WAY MORE info to come very soon!
You also may want to use a TPS if you are studying data logs to make tuning changes. This helps you know exactly what your foot was doing while driving.