No Change In MAP From Start to Run

NAME OF CODE:
No Change in MAP From Start to Run

WHEN MONITORED:
With engine RPM above 400 but less than 1500 and the throttle body at closed throttle.

SET CONDITION:
Too small a difference is seen between barometric pressure at ignition on and manifold vacuum (engine running) for 1.76 seconds.

THEORY OF OPERATION:
This sensor measures manifold absolute pressure and ambient barometric pressure within the manifold. It provides a 0 to 5-volt signal to Powertrain Control Module (PCM) cavity 36. The MAP sensor puts out a low voltage signal (0.5 to 1.8 volts) at idle when the manifold vacuum is high, and a higher voltage signal (3.9 to 4.8 volts) at deep throttle when the manifold vacuum is low. The MAP receives a 5-volt supply from PCM cavity 61; voltage may vary from 4.8 to 5.1 volts. The sensor ground is provided by PCM cavity 43.

POSSIBLE CAUSES:
- Restricted or leaking vacuum/pressure to MAP sensor
- Ice in sensor or passage
- Failed sensor
- Failed PCM