The manifold pressure sensor in your 2.4 liter GM engine is a big part of how your Pontiac Sunfire operates. When your Sunfire MAP Sensor fails or suffers an internal issue, your engine computer will have trouble operating your engine. This pressure sensor is mounted to your engine, and is responsible for reading the pressure in your intake manifold.
This reading is sent to your Pontiac Powertrain Control Module, and using this information the engine computer knows how much fuel to spray into your engine. Because of this reason if your Sunfire MAP Sensor goes bad it’s going to make your Sunfire run poorly. Today I’ll be showing you how to test a Sunfire MAP Sensor in a 2000 Pontiac Sunfire GT. This vehicle is equipped with the 2.4 liter engine and using a digital multimeter you can test the function of your MAP sensor.
There are several problems you’ll begin to see with your Pontiac when this sensor goes out. Here’s just a few of them below, before we begin our tutorial on testing your MAP sensor.
Symptoms of a failed Sunfire MAP Sensor
When your manifold absolute pressure sensor fails, you’ll have a number of issues. Some of these can range from annoying to dangerous, which is why you should always test your MAP sensor when you suspect a problem.
- Bad fuel economy
- Poor performance
- Engine hesitation
- cylinder misfire
- Check Engine Light ON
When your check engine light shows an issue with your MAP sensor, you’ll need to use a OBDII scan tool to retrieve the stored DTC.
How To Test your Sunfire MAP Sensor
Before you begin testing your manifold pressure sensor, you’ll need to insert your ignition key and turn to the “ON” position. Locate your Sunfire MAP Sensor and disconnect the pressure wiring harness.
Using your multimeter probe the front of PIN A with the key to the ON position. The wire from PIN A should be reading 5 volts of DC signal here.
Once you’ve tested that you MAP sensor is getting power, the next wire to probe is PIN C on the ENGINE harness side. This wire is the ground signal, and if you have both you know that your Sunfire MAP Sensor is being powered.
Testing the Sunfire MAP Sensor Signal
The last leg of this how to tutorial is to probe PIN B, which is the signal wire for your MAP sensor. This part of the test should be done with the harness plugged into the pressure sensor. Now once you have plugged the Sunfire manifold pressure sensor back in, pierce the wire coming out of the center pin with your multimeter lead.
With the key turned to the ON position, you should be reading 4.7 Volts of DC voltage. Now keep clear of your engine and the drive belts, and turn your engine on. Make sure to stay away from your engine and especially your cooling fans.
At idle the sensor should read between 3.6 – 3.9 volts of DC signal. As your rev your engine and increase vacuum the voltage should read lower. Double check to make sure the transmission is in neutral or PARK, and increase your engine speed. The voltage at this wire should lower smoothly, and there should be no gaps or spikes in voltage.
If your Sunfire MAP sensor does not respond with the right results, it’s time for a replacement MAP sensor. Replace the Sunfire MAP sensor and use a OBDII scan tool to clear your stored DTC trouble codes right away.
