What is the purpose of the MAP sensor.?

Question

I am getting a code for the MAP sensor on my 1994 GMC Sonoma pick up. 2.8 liter engine. I replaced the sensor and cleared the codes but after starting the engine the check engine light came on again. The engine is running extreamly rich. What would cause this.What is the purpose of the MAP sensor?

Answer 1

The MAP sensor measures the amount of vacuum in the manifold and electronically controls systems that in the old days were controlled by vacuum. For example the timing advance.

Answer 2

MAP sensor MAP stands for manifold absolute pressure.It tells the computer how much air is actually flowing through the manifold,another way of looking at it,it's vacuum,if you have changed the MAP and you still have a problem then look for a vacuum leak on the intake manifold after the throttle housing,it could even be the vacuum hose to the MAP try spraying the intake area with water in a squirt bottle if the engine stalls you have norrowed down where the leak is,TIP DISCONNECT MAP SENSOR WHILE YOU DO THIS,GMs have some adaptive memory so it will run not to bad with it disconnected while you try to locate the vacuum leak

Answer 3

Manifold Absolute Pressure Sensor

Answer 4

Now you know what the M A P stands for, and what its purpose is.
As for the code returning, check that the vacuum source that plugs onto the nipple is indeed showing vacuum. Check for a broken vacuum hose or hard-line, and check for restriction. Be certain that the manifold connection isn't restricted.
Check also the electrical connection(s) as well. The MAP sensor gets its vRef signal from the same terminal as does the throttle position sensor and the computer's coolant temperature sensor (the trucklett has one for the computer and one for the instruments). Make sure that there aren't short circuits at any of these components.
For testing, use only a DIGITAL voltmeter to avoid computer damage.

Answer 5

Did you rerun for codes. Maybe the sensor was defective. Are there other codes now. Maybe more than one item needs to be replaced. That is why it is sometimes worth it to go to an experienced computer technician.

Manifold Absolute Pressure (MAP) Sensor

The MAP sensor reads the vacuum or pressure in the manifold. This sensor provides key information for all Electromotive speed density based fuel injection systems, and is also used with the HPV-3B vacuum advance and boost retard. The sensor is available in 3 varieties for normally aspirated or boosted engines

Answer 6

The "map sensor" is exactly what it says. Manifold absolute pressure senor. You say you changed that and still have the light? Did you check for wire continuity before and after you changed the Map sensor? Your ECU is still getting a bad reading from your Map. Keep in mind that the ECU only detects out of range signals from electrical parts. If there is a mechanical problem, the ECU knows there is a problem but does not know where. So if your map is ok, look for a mechanical problem.....IE... An intake manifold leak with trip a map sensor fault.

Answer 7

This Site Might Help You.

RE:
What is the purpose of the MAP sensor.?
I am getting a code for the MAP sensor on my 1994 GMC Sonoma pick up. 2.8 liter engine. I replaced the sensor and cleared the codes but after starting the engine the check engine light came on again. The engine is running extreamly rich. What would cause this.What is the purpose of the MAP sensor?

Answer 8

Manifold Absolute Pressure sensor measures manifold vacuum and sends information to the ECM to control the fuel delivery spark advance and EGR flow. Did you make sure if this code might belong to two different sensors? My code book stops at 1993 but it shows it could also be a Mass Airflow Sensor. If these go out the computer gets all confused and it runs very rich and misfires and spits or tries to stall etc.

Answer 9

MAP sensor is manifold absolute pressure sensor. It senses the vacuum in the engine. If you have no vacuum to the sensor, the engine will run extremely rich. Check and see if there is actually vacuum getting to the sensor. If not the engine will run rich big time.

Answer 10

There you go. Manifold Air Pressure sensor reads Vacuum inside of the manifold low vacuum means hard acceleration and the map sensor voltage changes accordingly. Replace the sensor check the 3 wires too and the truck will run properly again.