What is it? Manifold Absolute Pressure sensor.






What does it do?

• Tells the computer (EEC) what the manifold vacuum is.
• Causes the EEC to increase the injectors' pulse width, adding fuel for the 'inferred' load.

How does it work?

• The device is a vacuum to frequency converter electronic device powered by the EEC 5 volt supply.The vacuum input changes the spacing of capacitance plates that changes the frequency of an oscillator circuit within a range of about 80 to 160 hertz over a normal operating range.This signal is detected by the EEC using an frequency to digital converter.This digital conversion is applied to fuel tables with consideration to engine RPM, ignition timing and Throttle Position.
• This operation is also related to the absolute barometric pressure that exists and any given time and affects the final applied result. i.e. changes response to terrain above sea level as well as weather pressure.

Trouble shooting

Additional Information

The MAP is a vacuum driven device and accounts for the ambient barometric pressure along with the engine vacuum level in Speed Density application. In mass air application the same device is used minus the vacuum application from the intake. The device is allowed to float at ambient barometric pressure. This is the only change between the two systems except the MAF system does not depend on the MAP for absolute fuel signal control. It's now the job of the mass air meter.

Lastly, in mass air application, its name is changed to BAP (barometric absolute pressure) sensor as it is the only function it does in this application.