ZEST BOLT Service Manual

ENGINE 1.3L QUADRAJET (90PS) 106 D. BOOST PRESSURE AND AIR TEMPERATURE SENSOR (i) Operational description The sensor supplies a voltage proportional to the measured pressure and is of piezo-resistive type (resistance varies with pressure). The ECU uses this information to determine: Q The mass of air absorbed by the engine (with the engine speed and air temperature parameters), Q The flow to be injected at the various engine load states and at the various atmospheric pressures, Q The ignition advance. An altitude correction is also made to the injection time calculation. The mass of air absorbed by the engine effectively varies as a function of: Q Atmospheric pressure, and therefore altitude, Q Air temperature, Q Engine speed. Pressure measurements are taken: Q Every time the ignition is switched on, At very high loads and low engine speeds (when driving up a hill, and therefore change in altitude and pressure). (ii) Boost air temperature information The resistance of the inlet air temperature sensor is of NTC type (Negative Temperature Coefficient), and therefore its resistance decreases as temperature increases. The ECU uses this information to calculate the mass of air absorbed by the engine. (iii) Fitment and location It is fitted on the air intake manifold and the signal sent to the engine management control unit makes it possible to: Q Regulate the turbocharger pressure; Q Protect the engine against overheating; Q Diagnose the operation of the air flow meter. (iv) Connection details and pin outs Pin Description Signal type 1 Earth Earth 2 Air temperature sensor Analogue output output 3 Power supply +5 V input 4 Pressure sensor output Analogue output The Turbo pressure & temperature sensor measures the pressure and the temperature in the intake chamber, downstream of the turbocharger. It is supplied by pin 23 of Connector M of ECU and receives a reference earth from pin 24 of Connector M. Asignal corresponding to the pressure level is sent to pin 41 of Connector M of ECU, the signal corresponding to the temperature is sent to pin 37 of Connector M.