08/17/2025
When replacing the TPS without fine-tuning it using a multimeter or scanner, the base voltage with the throttle fully closed should be around 0.5 V, increasing gradually to about 4.5 V as it opens. If the starting voltage is 1 V or higher, the ECU may interpret this as the accelerator being pressed, overriding IAC control and causing idle instability and sluggish throttle response.
The idle air control valve (IAC) is another component that suffers heavily from lack of maintenance. Over time, carbon deposits and oil vapors from the PCV system build up inside it, restricting airflowb and preventing the engine from properly regulating idle speed. Common symptoms include high idle, a drop in RPM when the air conditioning is engaged, or even stalling during braking or sudden stops. To prevent these issues, the IAC should be cleaned regularly with an electronic parts cleaner—removing it if possible—and ensuring that the air passage to the throttle body is free from obstructions.
A misadjusted TPS and a dirty IAC can both have a direct impact on drivability, often causing problems that are mistakenly blamed on more expensive sensors or the ECU itself.
It’s worth noting that these types of throttle bodies are no longer in production, but they can still be found in many vehicles from the 1990s and early 2000s.
