Map Sensor Reading in Inhg Key on Engine Off

Typically found in fuel injected engines, the manifold accented pressure (MAP) sensor is one of the sensors an engine control module (ECM) uses to calculate fuel injection for optimal air-fuel ratio past continuously monitoring intake manifold pressure information. More commonly a mass airflow (MAF) sensor is used in place of a MAP sensor, however, turbocharged engines volition typically utilize both a MAP and a MAF sensor.  The MAP sensor also provides a vital role in helping the ECM determine when the ignition should occur under varying engine load conditions.

Whichever sensor your engine uses, the ECM will not be able to optimize fuel injection without authentic air mass information from a working sensor. And poor air-fuel ratio at the very to the lowest degree will cause performance problems and premature engine wear. A MAP sensor failure can be difficult to diagnose, but with the help from Delphi Technologies, nosotros can explain what causes it, what to expect out for, and how to replace it if it fails.

How does a MAP sensor work?

The MAP sensor is typically located on the intake manifold, either next to or on the throttle torso itself. (On a forced-induction engine, the MAP sensor tin be constitute on the intake tract earlier the turbo.) Within the MAP sensor is a sealed bedroom that either has a vacuum or a controlled force per unit area that is calibrated for the engine. Dividing the sensor vacuum and the vacuum from the intake manifold is a flexible silicon wafer (a.k.a. 'fleck') with a current running through it.

The MAP sensor performs 'double duty' as a barometric pressure level sensor as soon as the primal is turned on.  With the key turned on (prior to the engine starting) there is no vacuum in the engine practical to the MAP sensor therefore it's point to the ECM becomes a baro reading helpful in determining air density.  When you lot get-go the engine, pressure in the intake manifold decreases creating a vacuum that is practical to the MAP sensor.  When you press on the gas accelerator pedal, the pressure level in the intake manifold increases, resulting in less vacuum. The differences in force per unit area will flex the chip upward into the sealed chamber, causing a resistance modify to the voltage, which in turn tells the ECU to inject more than fuel into the engine. When the accelerator pedal is released, the pressure level in the intake manifold decreases, flexing the clip back to its idle land.

The ECU combines the manifold pressure readings from the MAP sensor with data coming from the IAT (intake air temperature), ECT (Engine Coolant Temperature) sensor, baro reading and engine speed (RPM) to summate air density and accurately determine the engine'due south air mass period rate for optimal air-fuel ratio.

Why exercise MAP sensors fail?

Like most electric sensors, MAP sensors are sensitive to contamination. If the map sensor uses a hose, the hose tin can get clogged or leak and unable to read pressure changes. In some cases, extreme vibrations from driving can loosen its connections and cause external harm. Electric connectors can besides melt or crevice from overheating due to close proximity to the engine. In either of these scenarios, the MAP sensor will need to be replaced.

What to expect out for in a declining MAP sensor

A faulty MAP sensor will affect an engine's air-fuel ratio. If the ratio is incorrect, ignition inside the engine volition occur at an improper fourth dimension in the combustion cycle. If astringent pre-detonation continues over an extended fourth dimension, the internal parts of the engine (such every bit pistons, rods, rod bearings) will become damaged and eventually pb to catastrophic failure. Expect for these warning signs:

• Rich air-fuel ratio: Look for crude idle, poor fuel economic system, irksome dispatch and a strong odor of gasoline (especially at idle)
• Lean air-fuel ratio: Wait for surging, stalling, lack of power, hesitation on acceleration, backfiring through the intake, and overheating
• Detonation and misfire
• Failed emissions test
• Check engine light

A rebuilt engine is much more than of a hassle than replacing a sensor, so if your engine is experiencing any of the symptoms above, consider troubleshooting your MAP sensor.

Common MAP sensor mistake codes

Here is a listing of codes that are associated with the MAP sensor to look for if your check engine light has turned on:

• P0068: MAP/MAF - Throttle Position Correlation
• P0069: Manifold Absolute Pressure - Barometric Pressure Correlation
• P0105: MAP Excursion Malfunction
• P0106: MAP/Barometric Force per unit area Circuit Range/Performance Problem
• P0107: Manifold Absolute Pressure level/Barometric Pressure Circuit Low Input
• P0108: MAP Force per unit area Circuit High Input
• P0109: MAP / Baro Pressure Circuit Intermittent
• P1106: MAP/BARO Pressure level Circuit Range/Performance Problem
• P1107: Barometric Force per unit area Sensor Circuit Low Voltage

Note: Sometimes different sensors or other faulty parts can cause these codes to set. Even if your engine is experiencing the symptoms listed above and is firing one or more of the OBD-II codes listed, it is recommended to test the MAP sensor to ostend information technology is faulty.

How to troubleshoot a MAP sensor

Before any tests, inspect the physical appearance of the MAP sensor. Brainstorm by checking the connector and wiring for any damage, such as melted or cracked wires, and confirm there are no loose connections. Disconnect the sensor and audit the pins; they should be straight and clean with no signs of corrosion or angle. Side by side, inspect the hose (if applicable) connecting the sensor to the intake manifold for whatsoever signs of damage and that it has a tight connexion to the sensor. Lastly, take a look within the hose to make certain information technology is free of contamination.

If everything passes physical inspection, you tin exam the MAP sensor using a digital multimeter set to 20V and a vacuum pump.

1. With the battery on and engine off, connect the multimeter ground to the negative battery terminal and run a quick plausibility by checking the voltage of the battery. It should be effectually 12.vi volts.
2. Consult the manufacturer's service manual to identify the signal, ground, and 5-volt reference and back-probe the wires.
3. Turn the ignition switch on without starting the engine. The multimeter should (typically) display a voltage betwixt four.five to 5 volts for the v-volt reference, a steady 0 volts for the ground wire, and betwixt 0.v and i.v volts for the signal wire on non turbo applications and between 2.0 and three.0 for turbo applications. Consult OEM factory service information for the exact specs on your vehicle.
4. Commencement the engine with the signal wire back-probed. The multimeter should display a voltage between .5 to i.five volts at bounding main level on non turbo charged vehicles and 2.0 to 2.5 volts on turbocharged models.
5. Plough the engine off just keep the ignition on.
6. Under the hood, disconnect the MAP sensor from the intake only.
7. Connect a mitt vacuum pump and notation the current voltage from the signal wire.
8. Increase the vacuum on the sensor using the vacuum pump.
9. The voltage should steadily driblet as the vacuum increases.

If your voltage differs greatly on either test or the voltage change is erratic, the MAP sensor is faulty and will need to exist replaced.

How to supercede a faulty MAP sensor

Replacing a bad MAP sensor varies by vehicle, then delight consult the manufacturer'southward service manual for instructions for any specific instructions. Once the faulty sensor has been removed, information technology's a direct frontward installation for the new part.

1. Locate the MAP sensor on the intake manifold, either next to or on the throttle body itself, or on the intake manifold.
2. Remove any screws or bolts holding the sensor in identify.
3. Disconnect the electrical connector. Note: Exercise not forcefulness removal as the connector may contain a locking tab that may need to be removed prior to unlatching the connector from the sensor.
4. If applicative, detach the vacuum hose from the sensor. Note: It is recommended to supersede the vacuum hose with a new hose when replacing the sensor.
5. Compare the new and old sensors.
6. If applicable, reconnect the vacuum hose.
7. Reconnect the sensor electric connector.
8. Reinstall any screws or bolts that hold the sensor in place.
9. Double-cheque all connections to brand certain everything is secured.

Note: Depending on the vehicle and if a trouble lawmaking was set, a diagnostic tool may be required to reset the check engine lite.

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Source: https://www.delphiautoparts.com/usa/en-US/resource-center/making-sense-your-sensors-map-sensor

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