What is a MAP sensor and what does it do?

Refers to a manifold absolute pressure sensor, a variable resistor used to monitor the difference in pressure between the intake manifold at outside atmosphere.This information is used by the engine computer to monitor engine load (vacuum drops when the engine is under load or at wide open throttle). When the engine is under load, the computer may alter spark timing and the fuel mixture to improve performance and emissions

quote Originally posted by craigsfiero2007: ... manifold absolute pressure sensor ... used to monitor the difference in pressure between the intake manifold at outside atmosphere.

Close, but no cigar. Whet you described would be a differential pressure sensor. The MAP measures absolute pressure in the intake manifold ... i.e. manifold pressure with respect to a perfect vacuum. Absolute pressure is directly related to the density of the air in the intake manifold.

[This message has been edited by Marvin McInnis (edited 02-20-2008).]

Whoops, bad wording. Thanks for clearing that up.