How do MAP and MAF sensor enhancers work? -Where to look

How does the map sensor work?

Manifold absolute pressure (MAP) sensor signals are used electrically in the same way as mass airflow (MAF) sensor signals are used (although they are created internally differently).

It takes a 5 volt signal from the computer and returns a lower DC signal depending on the degree of vacuum of the engine. A higher output voltage means a lower engine vacuum, which is calculated as “more fuel needed”. The lower the output signal, the higher the engine vacuum that requires less fuel. But it’s not just fuel control. The MAP sensor signal provides the computer with a dynamic display of engine load. The computer then uses this data to control not only fuel injection, but also gear shift and cylinder ignition timing. In some cases, it is also used to calculate barometric pressure changes and automatically adjust to different altitudes.

How does the MAF sensor work?

Mass airflow (MAF) sensors help the computer calculate the flow and mass of air entering the engine. It does it by measuring the cooling effect of the air flow on the heated wire element. The electronics inside the sensor try to keep the sensor at a constant temperature.

Increasing the flow of air and cooling it further requires more current to maintain a constant temperature. The increase in current is converted into a signal, which is sent to the computer. In most cars, this signal is a high frequency signal. It’s not as high as radio waves, but it changes much faster than the (relatively) slow frequencies of oxygen sensors.

When the air flow is low, such as when the engine is idle, the MAF sensor produces a lower frequency signal. The MAF sensor raises the frequency when there is a lot of air flow, such as when the throttle load is wide open. The control module then converts these frequencies to the corresponding number of grams per second.

In addition, some MAF sensors may operate with a 0-5 volt straight DC signal, such as a typical MAP sensor. This is the case for some older MAP sensor designs where the potentiometer has a trap door connected to the shaft.

Enhancer

The invention we are talking about here is a simple play with resistors. A resistor is a small piece of carbon that blocks some current. The higher the value, the higher the resistance. A potentiometer (abbreviated as “pot”) is a resistor or variable resistor, and its value changes when the knob is turned. But it’s still just a resistor. As shown in the figure below, there is another resistor in series with the pot, a fixed value resistor.

The MAP or Manifold Absolute Pressure Sensor is a slightly more expensive device that is attached to the intake manifold or firewall and connected to the manifold with a thin hose. It contains 5 or 12 volts and senses the vacuum in the manifold and attenuates (reduces or weakens) this input voltage by a specific factor. In other words, it reduces the supply voltage to a DC voltage in the range of 15% to 60% of the supply voltage (these numbers change depending on the car design), and this changing (but not pulsed) signal It will then be sent back to your computer.

The placement of the resistors in the MAP sensor enhancer simply receives this already attenuated (decreased, weakened) signal and further attenuates it. If there is too much damping, the engine will stop and simply stop. Still, with proper control, tilt the mixture up to 20 from stoichiometry (a big word that simply means “balance of ingredients”) set at the factory to 14.7: 1 (14.7 parts of air and 1 part of gasoline). can do. : 1, probably 50: 1 or 100: 1.

The device is completely passive and works exactly the same as long as the incoming signal is at 12 volts, 5 volts, or on line. The figures in this book are the easiest way to do this. Cut the line from the sensor to the ECU and place the pot on the line as shown in the picture in the book. Further below, you will see an enhanced enhancer based on the same principle.