Manifold Pressure Sensor

The Manifold Absolute Pressure (MAP) sensor is used to convert the manifold pressure into an electrical signal for the ECU to use. The sensor works in absolute pressure, thus its calibration is not affected by changes in barometric pressure. The vacuum - and in the case of forced air induction engines, the pressure under boost - is proportional to the load under which the engine is operating, and the ECU uses the electrical signal as a load reference. A MAP Sensor is a powered sensor that typically has three wires; a 5V+ power wire, a signal wire to the ECU, and a Signal Ground.

This signal is sampled synchronously with engine position.

On this node, the MAP sensor calibration can be loaded or entered manually. If you have purchased a MAP sensor from Haltech, calibrations can be loaded directly into the calibration table by using the 'Load from File' button. Calibrations can be saved to file by using the 'Save to File' button. 

Filter

This table sets the filter for the Manifold Pressure value. A higher filter will increase filtering on the signal, but will delay the value used by the ECU for calculations. A lower filter will decrease filtering on the signal improving responsiveness to the signal but may allow noise to affect the value used by the ECU for calculations.

It is recommended that this filter only be adjusted if the MAP signal acts erratically under normal operating conditions. This value is the time constant for the MAP value to make a 63% change from the old value to the new one.

This table sets the derivative filter for the Manifold Pressure value.

MAP-Derivative is used as a rate of change channel for the MAP sensor. MAP-D is used by the Boost Control when closed loop is the method and a little extra filtering here is often required for consistent operation. 

Diagnostics

 

Raw Min / Raw Max - These settings define the minimum and maximum allowable raw input voltage values for the manifold pressure sensor. These diagnostic settings can be enabled to detect sensor wiring faults, such as the signal wire being shorted to ground or the power supply (5v).

Operating Min / Operating Max - These diagnostic settings define both the minimum and maximum operational limits of the sensor, to ensure that the sensor operates within safe parameters. Enabling these diagnostic settings allows the ECU to detect and flag any instances where the sensor readings exceed or fall below the specified range. This helps identify potential issues such as sensor malfunction or wiring faults, enabling timely troubleshooting and maintenance.

MAP Hose Failure - This diagnostic option is enabled when using a manifold pressure sensor that requires a hose connection between the sensor and the engine intake manifold. This setup is typical when utilizing the ECU's on-board manifold pressure sensor or a chassis-mounted manifold pressure sensor. Enabling this diagnostic setting allows the ECU to monitor the vacuum signal when the engine is running to detect possible defects like hose cracks, kinks, or disconnections.

Wiring

This node allows you to choose between an ECU On-board MAP sensor, or assign input for an external one. Manifold Pressure Sensors use a 0-5V analog voltage to read engine synchronous voltage. Any available AVI can be used, with the Pull Up set to disabled.