The manifold absolute pressure (MAP) sensor is an engine management system component that is critical to the smooth operation the engine in your vehicle. As such, when it fails, the engine will definitely resent it.
In this tutorial, I'm going to answer some of the most commonly asked questions about the MAP sensor.
Contents of this tutorial:
- What Does A MAP Sensor Do?
- What Happens When A MAP Sensor Goes Bad?
- What Problems Can A MAP Sensor Cause?
- How Can You Tell If A MAP Sensor Is Bad?
- How Can I Find Out If The MAP Sensor Is Bad?
- Can I Drive My Vehicle With A Bad MAP Sensor?
- Where To Buy The MAP Sensor And Save.
- More 3.1L V6 Buick, Oldsmobile Tutorials.
APPLIES TO: This tutorial applies to the following vehicles:
- 3.1L V6 Buick Century: 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005.
- 3.1L V6 Buick Regal: 1994, 1995, 1996.
- 3.1L V6 Buick Skylark: 1994, 1995, 1996.
- 3.1L V6 Oldsmobile Achieva: 1994, 1995, 1996, 1997, 1998.
- 3.1L V6 Oldsmobile Cutlass: 1997, 1998, 1999.
- 3.1L V6 Oldsmobile Cutlass Ciera: 1994, 1995, 1996.
- 3.1L V6 Oldsmobile Cutlass Supreme: 1993, 1994, 1995, 1996, 1997.
What Does A MAP Sensor Do?
The manifold absolute pressure (MAP) sensor's job is to measure intake manifold pressure. By pressure, I'm referring to the vacuum inside the intake manifold.
Here are some more specifics depending on whether your vehicle comes equipped with a MAF sensor or not:
If your a 3.1L V6 engine does NOT come equipped with a MAF sensor, then the MAP sensor is one of the sensors the fuel injection computer uses to calculate the amount of air entering the engine.
In case you're curious, the other two sensors are the intake air temperature (IAT) sensor and the crankshaft position (CKP) sensor.
If your 3.1L V6 engine does come equipped with a MAF sensor, then the MAP sensor is used to calculate engine load and to take a barometric pressure reading before the engine starts or when the throttle place is at wide open throttle (WOT) position.
What Happens When A MAP Sensor Goes Bad?
When the MAP sensor fails, it simply stops measuring and reporting the amount of vacuum inside the intake manifold.
Since the fuel injection computer relies on the MAP sensor's input to maintain the engine running smoothly, when it fail, engine performance and driveability will suffer.
The next section will go into more detail.
What Problems Can A MAP Sensor Cause?
When a MAP sensor fails, you'll see the check engine light illuminated by a MAP sensor diagnostic trouble code.
- If your vehicle is OBD II equipped (1995 or newer), you'll see:
- P0106: MAP Sensor System Performance.
- P0107: MAP Sensor Circuit Low Voltage.
- P0108: MAP Sensor Circuit High Voltage.
- If your vehicle is OBD I equipped (1994 or older), you'll see:
- 33: MAP Sensor Signal Voltage High.
- 34: MAP Sensor Signal Voltage Low.
You're also going to see one or more of the following symptoms:
- Bad gas mileage.
- Lack of power.
- Black smoke coming out of the tailpipe.
- Engine suffers a very rough idle.
- The engine may start and immediately stall.
- The engine has to be cranked longer than usual for it to start (this is called extended cranking).
- A heavier than normal exhaust smell when the engine is running.
- Won't pass the emissions test.
How Can You Tell If A MAP Sensor Is Bad?
The best way to find out if the manifold absolute pressure (MAP) sensor is bad or not, is to test it.
See the next section to find out more.
How Can I Find Out If The MAP Sensor Is Bad?
The MAP sensor can be tested with a multimeter to see if it responds to changes in vacuum pressure.
Testing the MAP sensor is the best way to find out if it's bad or not.
This is the basic MAP sensor testing procedure:
- Checking for MAP sensor trouble codes with a code reader or scan tool.
- Making sure that the MAP sensor is receiving 5 Volts DC.
- Making sure that the MAP sensor is receiving Ground.
- Making sure that the sensor's MAP voltage signal increases/decreases as vacuum is applied/released to it.
If the MAP voltage signal does not increase/decrease as you apply/release vacuum to the MAP sensor, then you can conclude that your vehicle's MAP sensor is bad and needs to be replaced.
The following tutorial will help you to test the MAP sensor using a vacuum pump and a multimeter:
Can I Drive My Vehicle With A Bad MAP Sensor?
Depending on the severity of the driveability problems that bad MAP sensor is causing, you probably won't be able to drive it.
Why? Because when the MAP sensor fails, it's either going to cause the fuel injection computer to inject too much fuel or not enough.
If too much fuel is being dumped into the engine cylinders, you risk:
- Damage to the catalytic converter.
- Accelerated wear and tear on the piston rings.
- Fuel will seep into the crankcase (across the piston rings) that will eventually start to dilute the engine oil.
If the MAP sensor is causing the fuel injection computer to inject less fuel, then you risk:
- Damage to the cylinder intake and exhaust valves. This is due to the fact that the engine is running on a lean air fuel mixture that will cause the cylinder head valves to run hotter than usual.
Any electronic fuel injection system problem should be diagnosed and resolved as soon as possible.
Where To Buy The MAP Sensor And Save
You can find the MAP sensor in any auto parts store. If you're wanting/needing to save a few bucks, then buying the MAP sensor online is the route to take.
The following links will help you comparison shop for the MAP sensor:
More 3.1L V6 Buick, Oldsmobile Tutorials
You can find a complete list of 3.1L V6 Buick (Oldsmobile) tutorials in this index:
Here's a small sample of the tutorials you'll find in the index:
- How To Test Engine Compression Test (3.1L V6 Buick, Oldsmobile).
- How To Test A Blown Head Gasket (3.1L V6 Buick, Oldsmobile).
- How To Test The Fuel Pump (3.1L V6 Buick, Oldsmobile).
- How To Test The 24X Crankshaft Position Sensor (1995-1997 3.1L V6 Oldsmobile Cutlass Supreme).
If this info saved the day, buy me a beer!
