Chrysler Front Wheel Drive Cars 4-CYL 1981-1995 Repair Information

Manifold Absolute Pressure (MAP) Sensor

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OPERATION



Chrysler Electronic Fuel Injection (EFI) and Multi-Point Fuel Injection (MFI) Systems

See Figure 1

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Fig. Fig. 1: The MAP sensor is mounted on the fire wall in the engine compartment

The MFI system is used on 2.2L and 2.5L turbocharged and flex fuel engines.

The manifold absolute pressure (MAP) sensor is a device which monitors manifold vacuum. It is connected to a vacuum nipple on the throttle body and electrically to the engine controller. The sensor transmits manifold vacuum conditions and barometric pressure changes to the engine controller. The MAP sensor data is used along with data from other sensors to determine the correct air/fuel mixture.

Eagle Throttle Body Fuel Injection (TBI) System

The Eagle TBI system is used only on 2.5L Premier engines.

The Manifold Absolute Pressure (MAP) sensor is mounted under the hood on the fire wall and is connected to the throttle body with a vacuum line. The MAP sensor reacts to pressure changes in the intake manifold, and sends this information the PCM. As engine load changes, the intake manifold pressure varies, causing the MAP sensors resistance to change. The change in the MAP sensor resistance results in a different input voltage to the PCM. The the MAP sensor also supplies the PCM with information relating to ambient barometric pressure during engine start-up (cranking) and to engine load while the engine is running. The PCM computes the signal received from the MAP sensor and adjusts the air/fuel mixture accordingly.

TESTING



Chrysler Electronic Fuel Injection (EFI) and Multi-Point Fuel Injection (MFI) Systems

This test should be performed with the engine cold (room temperature).

  1. Backprobe the dark green/red tracer wire from the MAP sensor connector with a voltmeter (do not unplug the MAP connector).
  2.  

A Diagnostic Read-out Box (DRB or DRB-II) can also be used to measure the voltage of the MAP sensor. For more information, refer to the scan tool's manufacturer's instructions.

  1. If a DRB scan tool is being used, set it up as follows: