1978 Ford FiestaFACTORY OEM SERVICE PROCEDURE

Manifold Absolute Pressure (Map) Sensor

This sensor monitors all changes in manifold pressure resulting from engine load, speed, and atmospheric pressure variations. The ECA applies a 9-volt reference voltage to sensor and monitors resultant output voltage to determine part throttle spark advance and EGR flow rate. The MAP sensor is mounted on the left rocker arm cover.

NOTE: A running change was made in the 1978 EEC I system. The Barometric Pressure Sensor and the Manifold Absolute Pressure Sensor were combined in a single housing.
Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.