The MAP sensor is used to convert the manifold pressure into an electrical signal for the ECU to use. The sensor works in absolute pressures, 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. There are five types of MAP sensors that can be used with the system. Which sensor is required depends on the engine set-up.
Sensor Name |
Range of Operation |
Application |
Haltech 1 Bar Sensor |
-100kPa to 0 kPa |
Normally Aspirated Engines |
Haltech 2 Bar Sensor |
-100kPa to 100kPa |
Turbo or Supercharged Engines up to 100kPa boost |
Haltech 3 Bar Sensor |
-100kPa to 200kPa |
Turbo or Supercharged Engines up to 200kPa boost |
Haltech 4 Bar Sensor |
-100kPa to 300kPa |
Turbo or Supercharged Engines up to 300kPa boost |
Haltech 5 Bar Sensor |
-100kPa to 400kPa |
Turbo or Supercharged Engines up to 400kPa boost |
Note: Make sure you have the correct MAP sensor for your engine. The first three digits of the part number are stamped on the sensor housing. |
The MAP sensor is usually mounted high on the engine bay firewall or inner guard using two screws, with the hose nipple facing outwards. Connect the sensor to the inlet manifold via a short length of vacuum hose and fasten with either hose clamps or nylon cable ties. Connect the sensor to the main wiring harness using the appropriate plug. Avoid mounting the sensor below the level of the fuel injectors, because fuel may collect in the vacuum hose and run down into the sensor. The sensor assembly is weatherproof but it is good practice to mount the sensor in a protected position away from moisture, heat and excessive vibrations.