Analog MAP Sensors

There are probably a dozen different ways to look at analog MAP sensors, this is the way I like to look at them, get the ground and signal off the sensor or the PCM, do a snap throttle, and look for the signal to go to its high volts limit, then go to its low volts limit, and then return to its idle volts position. This verifys the vacuum signal to the sensor as well as the sensor, the rise time to full volts should be quite fast if the hose is in good shape and not restricted by internal plugging or being collapsed or kinked. The fall time should be about the same speed and the voltage reading should approach a zero reading since vacuum is at its highest level after closing throttle at high rpm. Any other problem would be quite evident, such as no change in the signal, or the signal being high or low all the time.

Watch for spikes or dropouts in the signal as well, see example below.

lf your scope permits peak (glitch) detect, thats where you want it while checking this sensor. (dropout simulated)

More to come soon...