What Sense In Replacing Sensors?Whenever you're building a fresh computer-controlled engine, we strongly suggest the use of new sensors and controls in the interest of safe, reliable engine operation. This is the throttle position sensor, which gives the PCM (Programmable Control Module) feedback on throttle position. Elsewhere are sensors that detect coolant temperature, exhaust-gas oxygen content, inlet air temperature, and intake manifold vacuum. All these sensors need to be fresh because they each give the PCM specific feedback on a particular engine dynamic. Without that feedback, performance suffers badly.
We learned on the dyno that we needed a new Idle Air Control (IAC), which controls idle speed by creating a controlled vacuum leak at the throttle body. When we need a faster idle, the IAC creates a larger vacuum leak, which raises rpm. This happens when we turn on air conditioning or put the 4L60E automatic transmission in gear.