The purpose of this test is to investigate the operation of an analog type Manifold Absolute Pressure (MAP) sensor on a turbo diesel engine during idle, free revving and overrun conditions.
This known good waveform has the following characteristics:
With the engine running at idle the waveform shows a stable output of 2.4 V.
At around 1.7 s the voltage increases as engine speed increases.
At 2.5 s the voltage peaks around 4.1 V, at the peak engine speed.
There is a gradual voltage decrease over 2.5 s as the engine returns to the original 2.4 V idle condition.
MAP sensors, have two functions within an engine management system:
The sensor is mounted in the intake manifold and is usually a piezoelectric strain gauge.
MAP sensors have three electrical connections, usually designated as;
Typically, the sensor’s voltage output is proportional to the manifold air pressure.
On turbocharged engines manufacturers use sensors capable of measuring pressure both above and below atmospheric.
Note; the MAP sensor measures the absolute pressure in the intake manifold:
At sea level, atmospheric pressure averages about 1013 mbar or 101.3 kPa. Therefore, when the engine is off, manifold pressure measured by the MAP sensor will be 1013 mbar or 101.3 kPa.
Generally, MAP sensors fall into three pressure measurement categories;
Modern diesel engine turbochargers can produce around 2.7 bar boost. Having the wrong type of sensor in the engine will send false data to the Engine Control Module (ECM), resulting in erratic/poor performance and possible engine damage.
Symptoms of a faulty MAP sensor;
Remember these symptoms can also be manifested by engine intake and mechanical issues, blockages, leaks etc.
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.
We know that our PicoScope users are clever and creative and we’d love to receive your ideas for improvement on this test. Click the Add comment button to leave your feedback.