Lanos S Hatchback L4-1.6L DOHC D-TEC MFI (1999)
Manifold Absolute Pressure (MAP) Sensor: Description and Operation
The manifold absolute pressure (MAP) sensor measures the changes in the intake manifold pressure which result from engine load and speed changes
and converts these to a voltage output.
A closed throttle on engine coast down produces a relatively low MAP output. MAP is the opposite of vacuum. When manifold pressure is high, vacuum
is low. The MAP sensor is also used to measure barometric pressure. This is performed as part of MAP sensor calculations. With the ignition ON and
the engine not running, the powertrain control module (PCM)/engine control module (ECM) will read the manifold pressure as barometric pressure and
adjust the air/fuel ratio accordingly. This compensation for altitude allows the system to maintain driving performance while holding emissions low. The
barometric function will update periodically during steady driving or under a wide open throttle condition. In the case of a fault in the barometric portion
of the MAP sensor, the PCM/ECM will set to the default value. A failure in the MAP sensor circuit sets a diagnostic trouble code P1106 or P1107.
The following tables show the difference between absolute pressure and vacuum related to MAP sensor output, which appears as the top row of both
tables.
MAP
VACUUM
