The purpose of this test is to evaluate the voltage output and response time of an analog MAP sensor during engine idle, WOT and over-run conditions.
Connection for diagnostic work will vary dependent on application.
Technicians should whenever possible gain access to the test circuit without damage to seals and insulation. If this is not possible then make sure appropriate repairs are completed.
General connection advice
PicoScope offers a range of options within the test kits.
Dependent on difficulty of access, choose from:
Testing sensors and actuators (to include relevant circuit/connectors):
Use a vehicle circuit diagram to identify the Pressure Sensor output signal terminal at the control module if access allows.
Connect to Channel A of your PicoScope.
Start the engine.
Minimise the help screen and with the example waveform displayed on the screen PicoScope has already selected suitable scales for you to capture a waveform.
Select GO or press the space bar to see live data.
Carry out a Wide Open Throttle (WOT) test to capture your waveform.
With your live waveform on screen select STOP or press the space bar to stop your capture.
Turn off the engine.
Use the WAVEFORM BUFFER and ZOOM tools to examine your waveform.
The voltage at idle is 1.5 - 2.0 volts and rises as the pressure increases, reaching a maximum of approximately 4.0 volts. On overrun the voltage gradually drops back to idle levels. The hash that is evident on the waveform is a result of a slight pressure change due to engine induction strokes.
The sensor is mounted into the inlet air supply and is usually a piezoelectric strain gauge.
The sensor has three electrical connections.
The pressure sensor supplies the Engine Control Module (ECM) with a voltage that is proportional to the pressure within the intake system.
Note: A WOT test on a turbo charged engine will display lower results than you would get on an engine under load. However the WOT waveform will show the pressure changes within the system.
Selection of component-related Diagnostic Trouble Codes (DTCs):
P0105 - MAP Sensor Circuit Insufficient Activity
P0106 - Manifold Absolute Pressure (MAP) System Performance
P0107 - Manifold Absolute Pressure (MAP) Sensor Circuit Low Voltage
P0108 - Manifold Absolute Pressure (MAP) Sensor Circuit High Voltage
P0109 - Manifold Absolute Pressure Circuit Intermittent
P1101 - Actual measured airflow from MAF, MAP, EGR, and TP is not within range of the calculated airflow
P1106 - Manifold Absolute Pressure (MAP) Sensor Circuit Intermittent High Voltage
P1107 - Manifold Absolute Pressure (MAP) Sensor Circuit Intermittent Low Voltage
This help topic is subject to changes without notification. The information within is carefully checked and considered to be correct. This information is an example of our investigations and findings and is not a definitive procedure. Pico Technology accepts no responsibility for inaccuracies. Each vehicle may be different and require unique test settings.
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