The fuel system on your 4.7L Dodge Durango (Dakota) is a speed density type. This means that it relies heavily on the info the MAP sensor provides to calculate the amount of fuel the PCM has to inject into the engine.
So, when the manifold pressure (MAP) sensor fails, your 4.7L Dodge Durango (Dakota) is gonna' resent it in a major way! Thankfully, testing the manifold absolute pressure (MAP) sensor can be accurately and easily be done using only a multimeter and a vacuum pump.
In this tutorial I'll explain how to bench test it (although you'll be leaving the MAP sensor connected to its electrical connector). You'll be able to either condemn the MAP as defective or eliminate it as the source of the diagnostic trouble code or drive-ability issue your 4.7L Dakota (Durango) is going through.
Contents of this tutorial:
You can find this tutorial in Spanish here: Cómo Probar El Sensor MAP (2000-2001 4.7L Dakota, Durango) (at: autotecnico-online.com).
Symptoms Of A Bad MAP Sensor
Since the manifold absolute pressure (MAP) sensor is such a critical component of your Dakota's (Durango's) fuel injection system, when this bad boy fails your pick-up (SUV) is going to feel it!
The two most obvious symptoms of a bad MAP sensor is that the check engine light will be shining nice and bright and that the engine is going to idle very rough.
Here are a couple more symptoms of a bad MAP sensor:
- The check engine light (CEL) will be on with a MAP diagnostic trouble code (DTC) stored in the computer's memory.
- Diagnostic trouble codes (DTCs):
- P0107: MAP Sensor Signal Voltage Low.
- P0108: MAP Sensor Signal Voltage High.
- Your Dodge Durango (Dakota) won't start or will have a long cranking time before it starts.
- Black smoke coming out of the tailpipe along with really bad gas mileage.
- The engine idles rough when running and has a lack of power when accelerated.
TEST 1: Checking The MAP Sensor Signal
In a nutshell, the MAP sensor's job is to measure the amount of vacuum in the intake manifold. This vacuum measurement info is sent to your Durango or Dakota's PCM as a DC voltage signal. This MAP voltage signal can easily be tested with a multimeter in Volts DC mode.
To test the MAP sensor on your 4.7L Dakota (Durango), we're not gonna' rely on the engine's vacuum. What we'll do is supply our own vacuum using a vacuum pump. Manually supplying vacuum to the MAP sensor will give us an extremely accurate test result.
NOTE: If you don't own a vacuum pump... don't worry. You can use your mouth to apply vacuum to the MAP sensor (via a vacuum hose). This method won't produce the same test result because applying vacuum with your mouth won't be able to bring down the voltage to 1.1 Volts. The important thing is just to see the voltage go down and then go back up (to its original value) when you apply vacuum with the ‘good ole' lungs’.
OK, to get this show on the road, this is what you need to do:
Remove the MAP sensor from its place on the intake manifold or throttle body.
Connect your vacuum pump to the MAP sensor's vacuum port. If you had to disconnect the MAP sensor from its electrical connector to remove it, reconnect it to it now.
Probe the DK GRN/RED wire of the MAP sensor connector with your multimeter in Volts DC mode. The DK GRN/RED wire is the MAP signal wire.
NOTE: Remember, the MAP sensor must remain connected to its 3 wire connector.
Ground the black multimeter test lead directly on the battery negative terminal.
Turn the Key on but don't start the engine. At this point your multimeter should register 4.7 Volts DC.
Now, pump the vacuum pump to apply vacuum to the MAP sensor. The multimeter should register a decrease in the voltage number (with about 20 in. Hg of vacuum applied, your multimeter should read about 1.1 to 1.7 Volts DC.).
Repeat this test step several times and each time, you should see the same values on your multimeter.
OK, let's take a look at what your vacuum pump test results mean:
CASE 1: Your multimeter registered the indicated voltages as you applied/released vacuum. This means that the manifold absolute pressure (MAP) sensor is good. It also means that the MAP sensor is NOT behind the MAP sensor trouble code.
Now, if your vehicle still has the MAP sensor code lighting up the check engine on your instrument cluster, take a look at the section: MAP Code Won't Go Away for more info.
CASE 2: Your multimeter registered a voltage value, but it did not increase or decrease as you applied vacuum. This confirms that the manifold absolute pressure (MAP) sensor is bad Replacing the MAP sensor will solve the MAP code issue (P0107 or P0108)
CASE 3: Your multimeter registered 0 Volts. This usually means that the MAP sensor is fried. To be absolutely sure, you'll need to confirm that MAP sensor has power and Ground. If both (power and Ground) are present, the MAP sensor is bad. To test for power, go to: TEST 2: Verifying The MAP Is Getting Power.