Recommend you check your MAP sensor. You will need a voltmeter. Fig. Fig. 1: Manifold Absolute Pressure (MAP) sensor circuit Fig. Fig. 2: MAP sensor voltage specifications Fig. Fig. 4: On the 3.8L (VIN K) engine, the MAP sensor (1) is mounted in the PCV valve cover (2)
If you don't have a vacuum gage, just use your mouth to pull a vacuum on the hose and see if the voltage drops when you do.
Let me know if you have questions.
OPERATION
The Manifold Absolute Pressure (MAP) sensor, used on 1996-99 vehicles, measures the changes in intake manifold pressure which result from engine load/speed changes, and converts this information to a voltage output. The MAP sensor reading is the opposite of a vacuum gauge reading: when manifold pressure is high, MAP sensor value is high and vacuum is low. A MAP sensor will produce a low output on engine coast-down with a closed throttle while a wide open throttle will produce a high output. The high output is produced because the pressure inside the manifold is the same as outside the manifold, so 100 percent of the outside air pressure is measured.
The MAP sensor is also used to measure barometric pressure under certain conditions, which allows the PCM to automatically adjust for different altitudes.
The MAP sensor changes the 5 volt signal supplied by the PCM, which reads the change and uses the information to control fuel delivery and ignition timing.
TESTING
See Figures 1 and 2
When pumping up and releasing the vacuum, check to make sure the voltage readings are smooth. When applying vacuum to the sensor, the change in voltage should happen instantly. A slow change in voltage could point to a faulty sensor.
REMOVAL & INSTALLATION
3.8L (VIN K) Engine
See Figure 4
On these engines, the MAP sensor is mounted to the PCV valve cover.
To install:
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