At key on and engine not running the Manifold Absolute Pressure (MAP) Sensor should always match the Barometric Absolute Pressure (BAP) Sensor. As well as providing altitude correction, the BAP sensor also allows the MAP sensor to be calibrated prior to tuning.

Link G4X ECUs use an on-board barometric sensor that is calibrated prior to dispatch. This ensures that all PCLink Tuning Software programs (pclx Files) give a consistent state of tune throughout the ECU range. This allows a pclx file to be transferred between G4X based ECUs giving an equivalent state of tune providing all factors affecting volumetric efficiency are equal.

Without the ability to calibrate all the available types of MAP Sensors to the BAP Sensor there would be significant affects on the accuracy of the resulting tune, especially when tuning with Manifold Gauge Pressure (MGP) as a load index.

To calibrate the MAP sensor:

1.Connect a laptop/notebook PC to the ECU and connect to the ECU using PCLink.

2.Under the Analog Channels menu, select the An Volt channel that has been wired to the MAP sensor. Select the correct MAP Sensor Type.

3.Under the 'Options' menu, select 'MAP sensor calibration'.

4.Follow the on screen instructions.

5.Select the 'Analog Inputs' tab in the runtime values section of PCLink (lower part of the screen).

6.Compare the MAP and BAP values and ensure they have a similar reading (within 1 kPa).

7.Perform a 'Store' by pressing F4.

 

A more in depth explanation is provided in the PCLink help Manual under PCLink G4X Users Manual -> Tuning Operating Procedures -> ECU Controls -> MAP Sensor Calibration.