How to Replace the MAP Sensor in a 1989 Jeep Comanche

The 1989 Jeep Comanche was offered with a 2.5-liter in-line four-cylinder engine or a 4.0-liter high-output in-line six-cylinder engine. Despite the different engine configurations, the manifold absolute pressure, or MAP, sensor is on the center firewall, behind the valve cover, in both. The MAP sensor is connected to the throttle body by a vacuum hose and detects the absolute pressure of the intake manifold. As the engine speed increases or decreases, the resistance of the sensor changes, providing the computer with a voltage signal ranging from 0.5 volts to 5.0 volts. The computer uses the signal from the MAP sensor, along with signals from other sensors, to adjust fuel/air delivery and emissions controls to improve driving conditions and emissions levels.

Instructions

Lift the vehicle hood and support it with the hood prop rod. Allow the engine to cool before continuing to prevent injury from hot engine components.

Look behind the engine around the center of the firewall to locate the MAP sensor. It is rectangular and has a single electrical plug, a single vacuum line and two nuts that secure it to the firewall.

Pry up on the electrical connector tab with your thumb and slide the connector out of the MAP sensor. Disconnect the vacuum line at the sensor by gently pulling it off the MAP sensor nipple.

Remove the two retaining nuts with the socket and ratchet. Remove the MAP sensor from the engine bay.

Slide the new MAP sensor onto the studs on the firewall. Install the two retaining nuts and tighten snug with the socket and ratchet.

Place a small amount of dielectric grease into the wiring harness plug. Slide the plug into the electrical receptacle on the MAP sensor until the locking tab clicks into place.

Slide the vacuum hose from the throttle body onto the nipple on the MAP sensor. Shut the vehicle hood.