Chart C1D - Map Output Check

The MAP sensor measures manifold pressure (vacuum) and sends that signal to ECM. The ECM uses this information for fuel and spark control.

1. Check MAP sensor output voltage to ECM. This voltage, without engine running, represents a barometer reading to ECM.
2. Applying 34 kPa vacuum to MAP sensor should cause voltage to be 1.2 volts less than voltage at step 1). Upon applying vacuum to sensor, change in voltage should be instantaneous. A slow voltage change indicates a faulty sensor.
3. Check vacuum hose to sensor for leaking or restriction. Be sure no other vacuum devices are connected to MAP hose.

Fig 1: Chart C1D Schematic, TBI Map Output Check

Fig 2: Flow Chart C1D, TBI Map Output Check