Part 2: Linear vs. Nonlinear Throttle Position Sensor Response
Throttle control becomes a challenge when the engine demands rapid response, and the linear TPS struggles to keep up. This post examines why linear potentiometers fall short and how adjusting their response curve can provide a solution.
Figure 2 highlights the mismatch between a linear TPS response and actual airflow requirements. The black line represents a direct 1:1 coupling between the TPS and the throttle shaft. The green curve, however, shows the desired convex response that aligns with engine needs.
Key insights include:
- Mismatch in Early Throttle Movement:** The green curve rises more steeply at low throttle positions, reflecting the higher enrichment needs during acceleration.
- Ideal Response Curve:** The convex green line ensures sufficient enrichment at every throttle position, particularly in the critical 0°-60° range.
Engines using a linear TPS often struggle to deliver sufficient enrichment during rapid acceleration. This is particularly evident in high BSFC engines, where the fuel-air mixture must be carefully managed to avoid performance losses. The green curve offers an ideal enrichment profile, ensuring smooth transitions and crisp throttle response.
A mechanical or electronic modification is necessary to create the desired convex TPS response curve. In Part 3, we’ll dive into these potential solutions and their implications.
Towards a Solution
A mechanical or electronic modification is necessary to create the desired convex TPS response curve.
In Part 3, we’ll dive into these potential solutions and their implications.