Manifold Absolute Pressure (Map) Sensor
- A malfunction in the MAP sensor circuit should set a related code in ECM memory. If a code is present, see appropriate article below:
An out-of-calibration sensor may not set a trouble code. Use following procedure to test sensor calibration. If driveability problems exist, MAP sensor failure is suspected and no MAP code is present, disconnect MAP sensor connector. If driveability condition improves, replace MAP sensor. Before replacing MAP sensor, check MAP vacuum hose for splits, kinks, proper routing and blockage.
- With ignition on and engine off, check MAP sensor parameter using a Scan tester connected to the ALDL connector. Voltage should be as specified in MAP SENSOR VOLTAGE RANGE table. If MAP sensor voltage is as specified, go to next step. If voltage is not as specified, check for 5-volt reference supplied to sensor. Check harness integrity. If no problems are evident, replace MAP sensor.
- Using a hand-held vacuum pump, apply 10 in. Hg to MAP sensor and note voltage change. Voltage should drop to about 1.0-1.5 volts less than specified in table. If voltage is not as specified or voltage reading does not immediately follow vacuum change, MAP sensor is faulty.
MAP SENSOR VOLTAGE RANGE
| Altitude (Ft.) | Range (Volts) |
|---|---|
| Below 1000 | 3.8-5.5 |
| 1000-2000 | 3.6-5.3 |
| 2000-3000 | 3.5-5.1 |
| 3000-4000 | 3.3-5.0 |
| 4000-5000 | 3.2-4.8 |
| 5000-6000 | 3.0-4.6 |
| 6000-7000 | 2.9-4.5 |
| 7000-8000 | 2.8-4.3 |
| 8000-9000 | 2.6-4.2 |
| 9000-10,000 | 2.5-4.0 |