MoTeC M880 - Manual (Page 23)

MoTeC Installation 21
Avoid severe vibration of the sensor as this can cause fluctuations in the
reading. Do not mount rigidly to the engine. Normally the pressure sensor is
mounted to the vehicle body.
If used for Manifold Pressure Sensing
For normally aspirated engines use a 100 kPa sensor.
For turbo charged engines a 300 kPa absolute sensor will measure up to 200
kPa (29 psi) of boost (above Atmospheric). If higher boost will be achieved a
sensor with a higher pressure range will be needed.
The sensor should be connected to the inlet manifold plenum via a short hose
(less than 1m). The sensor should be mounted above the level of the plenum
with the port facing down to avoid moisture accumulating on the sensor
element. The hose should run downwards all the way to the plenum.
The plenum take off point should be at a position that best represents the
average manifold pressure and has minimal pressure pulsations. A small
restrictor may be needed at the manifold end of the hose to help reduce
pressure pulsations. The take off point should not be teed in with other items
such as idle speed control valves as they can affect the pressure reading.
If used for Barometric Pressure Sensing
Use a 105 kPa sensor.
Vent the sensor to the atmosphere with the port facing down.
Avoid mounting at a point where air buffeting occurs, any pressure
fluctuations will directly affect the mixture.
It may be desirable to sense the pressure at the air intake as the pressure
may vary due to aerodynamic effects.
Air Temp Sensor
The Air Temperature sensor is mainly used to correct for air density change
due to air temperature variation.
The sensor contains a temperature dependant resistor and is designed for
high speed response in an air flow.
The Air Temp sensor must be placed to measure the air temperature before
the butterfly (and after the inter cooler on turbo charged engines).
Avoid placing the sensor too close to the stand-off vapour in a multi-runner
manifold as this will cool the sensor and give a false reading.