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Boost pressure -100 kpa g

MoTeC M1 Software Tutorial

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Hey. I am experience some issue with boost pressure sensor in M1 GPR, While engine is not running boost pressure channel shows -100 kpa g, meanwhile sensor translation channel shows 0 kpa g. something is subtracting 100 from my value.

Hi,

The Boost Pressure sensor channel is an Absolute Pressure channel, so with the engine off this should be showing the ambient pressure. The M1 then calculates from this value the boost pressure seen (pressure - ambient).

Hi,

The Boost Pressure and Boost Pressure Sensor channels are linked but not the same, the Boost Pressure channel is calculated using the Boost Pressure Sensor channel value less Ambient, so you need to have the Boost Pressure Sensor channel (Boost Pressure will be reading around 0 kPa g) reading an ambient value (around 100 kPa at sea level) with the engine off. When the engine is running, this channel should remain around ambient (depending on restrictions in the inlet tract) until the pressure in the inlet tract rises above ambient. Once this happens the Boost Pressure channel will start to rise in line with the increase in pressure over ambient.

In the case that there is not a Boost Pressure Sensor installed, if the Inlet Manifold Pressure Sensor is reading 220kPa a, then the Boost Pressure value will be (220kPa a - Ambient Pressure (assume 100kPa a)) = 120 kPa g.

If you do not have an Ambient Pressure Sensor installed, the M1 will read the initial stable pressure reading from the Inlet Manifold Pressure Sensor on startup (so before the engine is cranked) and set that as the Ambient Pressure value.

Stephen,

Got it. I just was exhausted with crazy schedules. Thanks for helping me.