Where is the map sensor on a 1998 Pontiac Bonneville?

Answer 1

AnswerIt is on top of the PCV valve on the front of the engine by the alternator. (normally aspirated, non supercharged models only). The location depends on whether you have a normally aspirated 3800 V-6 (as in the SSE model) or the supercharged 3800 V-6.

On the supercharged model (SSEi) there are 2 map sensors mounted on a bracket above the rear valve cover, connected to the vacuum hosing. Each sensor is held on the bracket with 2 screws. One sensor runs the supercharger boost gauge, the other is used for engine management. The electrical connectors are identical, and it doesn't matter which sensor they are attached to, other than the fact you don't want to attach them in such a way as to tension the wires and cause damage to the wiring harness or connectors. There is a lot of emissions wiring and hoses that can interfere with getting to the sensors, along with spark wires, etc, so they are not easy to see in poor lighting. They connect to the vacuum hoses underneath, so carefully remove them, as on a car this old, the rubber connector and stiff vacuum piping can be brittle from engine compartment heat, and tear or break very easily. Any vacuum leaks can cause high engine idle speeds along with other driveability problems.