Anything that interferes with the MAP sensor's ability to monitor the pressure differential may upset the fuel mixture and ignition timing. This includes a problem with the MAP sensor itself, grounds or opens in the sensor wiring circuit, and/or vacuum leaks in the intake manifold (airflow sensor systems) or hose that connects the sensor to the engine.
Typical drivability symptoms that may be MAP related include: * Surging.
* Rough idle.
* A rich fuel condition, which may cause spark plug fouling.
* Detonation due to too much spark advance and a lean fuel ratio.
* Loss of power and/or fuel economy due to retarded timing and an excessively rich fuel ratio.
A vacuum leak will reduce intake vacuum and cause the MAP sensor to indicate a higher than normal load on the engine. The computer will try to compensate by richening the fuel mixture and retarding timing -- which hurts fuel economy, performance and emissions.