Air intake pressure sensor - Bosch common rail diesel

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 guidance

Connection for diagnostic work will of course 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,

  1. Breakout leads.
  2. Back-pinning probes.

Testing Sensors and Actuators; (to include relevant circuit/connectors).

  • When testing a sensor, it is desirable to gain access at the control module.
  • When testing an actuator, it is desirable to gain access at the actuator.

How to perform the test

  1. Use a vehicle circuit diagram to identify the Pressure Sensor output signal terminal at the control module if access allows.

  2. Connect to Channel A of your PicoScope.

  3. Start the engine.

  4. 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.

  5. Select GO or press the space bar to see live data.

  6. Carry out a Wide Open Throttle (WOT) test to capture your waveform.

  7. With your live waveform on screen select STOP or press the space bar to stop your capture.

  8. Turn off the engine.

  9. Use the WAVEFORM BUFFER and ZOOM tools to examine your waveform.

Example waveform

Waveform notes

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.

Waveform Library

The Waveform Library has 50 examples of analog air intake pressure sensors listed.

Go to the drop-down menu bar at the lower left corner of the Waveform Library window and filter for manifold absolute pressure sensor (analog).

Further guidance

Technical Information

The sensor is mounted into the inlet air supply and is usually a piezoelectric strain gauge.

The sensor has three electrical connections.

  • Pin 1 = Battery volts supply.
  • Pin 2 = earth circuit.
  • Pin 3 = output signal volts.

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.

Generic DTC’s MAP Sensor.

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

GT010-4

Disclaimer
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.

Suitable accessories

  • Premium 6-way breakout lead set

    £269.00

  • Back-pinning Probe Set

    £48.00

  • Flexible Back-pinning Probe

    £4.25

  • Large Dolphin/Gator Clips

    £10.00

  • Premium Test Lead: BNC to 4 mm, 3 m

    £47.00

  • Premium Test Leads: Set of four leads 3 m (TA125 - TA128)

    £179.00

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Guided test: Analog (Turbo Diesel)