This article is about MAP sensor.
What is a Manifold absolute pressure sensor?
In today’s vehicles the fuel utilization of an engine is controlled through sensors. These sensors is very important for the smooth running of vehicles. The control unit of the engine is brought together to the sensors and gather data from it. Then the control decides what to do.
The manifold absolute pressure sensor or MAP sensor is used in electronics control system. MAP is used in internal combustion engines.
MAP sensor is used in that engine which is fuel injected. A manifold absolute pressure sensor gives pressure data to the electronic control unit (ECU) of the engine.
The data which is provided by MAP sensor is used to calculate air density and to find air mass flow rate of the engine, which is then used to know how much fuel is needed for consumption and to control the timing of ignition. Mass airflow sensors is used to determine the air flow intake in the fuel engine. Force induction engine used both sensor MAF and MAP sensor. Cold air intake uses MAF sensor while post turbo intake uses MAP sensor.
The data which is collected by MAP sensor is converted with the help of a second variable which is coming from another sensor known as IAT sensor (intake air temperature sensor). This method is called speed density method.to determine fulling of the engine, the speed of the engine (RPM) is also used to determine, or we can say speed density (engine speed/air density). the MAP sensor is used to test the functionality of EGR (exhaust gas circulation) valve, so MAP sensor is also used in OBD II (on board diagnostic).
Working Principle of MAP Sensor
MAP sensor is an input sensor which is used to notice the engine load to give signal to the control unit. These signals are proportional to the sum of vacuum. The computer of engine then uses this information for different works that as to change explosion timing and fuel improvement.
When the engine is on load the vacuum ignition try to fall due to wide throttle. To maintain the air and fuel ratio stability the engine used more fuel or air. Once the engine gets signal from the sensors, then it combines the fuel from the regular to go richer to make sure the engine generates some extra power.
At the same time the computer of the engine holds up the explosion timing to stop ignition because it can harm the engine and its performance. When the vehicle travel with light weight and the condition gets modified then the engine provides low power.
If the clock does not open wide or blocked, then it causes the intake vacuum to enhance. The map sensor senses it and gives signals to the computer. The computer instantly reacts and suddenly draws back the blend of fuel to decrease the use of fuel and enhance the ignition timing.
The problem caused of faulty MAP sensor
In a vehicle faulty MAP sensor can cause different issues. If the MAP sensor shows incorrect reading about fuel utilization the fuel management system will draw more fuel than needed, so it will reduce fuel economy. While if the MAP sensor manifests low reading, then the computer will decrease the amount of fuel utilization and it will hollow the engine, so it will produce less power. Thus, if the sensor does not work properly the vehicle will fail the emission test.
Error Codes Show by the MAP Sensor
- P0068
- P0069
- P1106
- P1107
The Factors of Causing This Fault
There are different factors which make these issues in the MAP sensor that as these factors can be electronic and mechanical components. There is vacuum chamber in the MAP sensor which allows the sensor to sense changes in the manifold pressure. Over time a leak can occur in the vacuum chamber, which creates the sensor to read the data incorrect. The fluctuation comes in the temperature and vibration can also affect the MAP sensor. Dirt and other contamination are also the big fact to affect the sensor, which prevents the sensor from accessing the intake air flow.
How to Repair a MAP Sensor
To change the faulty MAP sensor which is bolted or screwed to the throttle or manifold intake body. Simply remove the bolt or unscrew it and remove the faulty sensor, after that reinstall a new one and screw it back.
Broken MAP Sensor Signs
The broken map sensor will have the following signs.
- Lean air and rich air fuel ratio
- Surging
- Poor fuel economy
- Cannot work properly.
- Engine will face power problem.
- Stalling
- Misfire and donation
These problems can be solved through DMM (digital multimeter) and vacuum pump.
What are the Symptoms of a Faulty MAP Sensor
Poor fuel economy
If low or no volume is sensed by ECM, it means that the engine is an underload condition. It will draw more fuel in this case, and it will also increase the spark timing. In this case fuel consumption will increase and fuel economy will decrease.
Lack of power
If ECM shows high vacuum, it means that the is on no load condition. In this case the fuel consumption will reduce, and spark timing will increase. Fuel utilization can be cut down which sound to be good thing but if the fuel utilization is not enough the engine can decrease acceleration and passing power too.
Rough Idle
Insufficient fuel injection can affect the performance of the engine. Due to this rough idling and misfiring can occur.
Hard starting
The rich or lean mixture of fuel can also produce some issues in the engine that as this mixture makes it difficult for the engine to start.
Hesitation or stalling
Moving on a gas is not easy when starting from the stop or trying a passing operation. If ECM manifests a lean mixture because of faulty MAP sensor.
A faulty MAP sensor will read nothing or a failing MAP sensor will give incorrect data.
Application of a MAP Sensor
- MAP sensor is used to decide the fuel usage.
- It is also used to decide the fuel delivery.
- It is used to inform the RPM variation.
- It is used to adjust with the altering environment.
Example
Consider these two conditions.
Condition 1:
when an engine is operated on the top of high mountain at wide open throttle (WOT). The pressure of the engine will 50KPa.
Condition 2:
If the same engine is operated at sea level and if has the same pressure 50KPa. But the WOT will be less before reaching because of barometric pressure will high.
Because the same mass of air is invaded to the cylinder, the engine will need the same mass of fuel.
Now if the throttle is open in the second condition, the manifold pressure will increase from 50 KPa to 100KPa. The density of air is rise by manifold due to absolute pressure which is in the intake. Thus, to get higher output more fuel will be burnt.
Examine an example of varying RMP and engine load.
If the engine has 60KPa pressure at 1800 RPM while the engine is in an no loaded condition. If load is applied to the engine the pressure will rise to 100 KPa and the engine will yet be at 1800 RPM, but the engine will demand more fuel intake.
Vacuum comparison
Engine vacuum is the difference between the manifold pressure and the atmospheric pressure. The engine vacuum is measured in “gauge” and gauge the measure the pressure difference and cannot measure absolute pressure. But engine response to the air mass, and to measure the absolute pressure it needs to calculate mass. The mass that gets into the engine is proportional to the air density, and this is proportional to the MAP and inversely proportional to the absolute pressure.
What is an EGR Testing
During driving the EGR valve need to be tested for usefulness. This test is done through OBD II standard. While some manufacturers use MAP sensors to do this test. In the vehicles there are MAF sensors for primary load and For checking and testing the MAP sensor is use. This test is done during the low deceleration of the Vehicle. When there is low pressure in the intake manifold it means a high vacuum present in the intake manifold as compared to the outside. The PCM (Powertrain Control Module) is used to open the EGR valve and monitor the MAP sensor value. If exhaust gas invades the manifold absolute pressure rises, if the EGR works properly then.
Common Confusion with Boost Sensor and Gauges
Absolute pressure is measured by MAP sensor while gauge is used to measure the amount of pressure. That absolute pressure is around 100KPa, and this is a gauge pressure. Boost and absolute pressure have some relationship as one pressure increase the other will also increase and when the one decreases the other will also decrease.
For boost pressure the reading is –100KPa. MAP sensor will always measure 100KPa. A MAP sensor is not able to measure negative pressure, whereas when MAP shows zero it means there is no pressure. Vaccuum is measured as a negative pressure compared to normal atmospheric pressure. Vacuum boost sensor can read negative pressure. In force induction engine the negative reading show that the engine is drawing air faster than the supplied.
Common fault codes of MAP sensor
Codes when the MAP sensor does not work correctly.
- P0068: correlation of throttle position. MAP and MAF both can show this code.
- P0069: manifold absolute pressure, correlation of barometric pressure
- PO105: MAP circuit malfunction
- PO106: show performance problem.
- PO107: manifold absolute pressure
Frequently asked question FAQs about MAP sensor:
Q 1: can I drive my car with a faulty MAP sensor?
Ans: yes, you can drive your car with the fault sensor. When the MAP sensor is not working properly the fuel utilization will be high and it can wound the engine and exhaust system.
Q 2: will a MAP sensor cause misfire?
Ans: yes, if the MAP sensor gathers wrong data and gives false signal to the computer, the computer will give a signal for more fuel. It will cause a rich mixture which can foul the spark plugs and can create a miss fire.
Q 3: can you clean the MAP sensor?
Ans: you can use electric parts cleaner. Take a soft rag or paper towel to clean the outside body of the sensor and then let it dry.
Q 3: What is the price of MAP senor?
Ans: the price of the map sensor starts from 30$ to 200$.
Q 5: can I use alcohol to clean a MAP sensor?
Ans: use electric parts cleaner for the outer surface and spray alcohol over the MAF sensor but make sure to cover the MAF sensor wires.
Great keep it up l learn a lot. Thanks for writing on this topic