How Does The Map Sensor Work?
The manifold Absolute Pressure (Map) sensor signal is electrically used in a similar way to the use of Mass Air Flow (Maf) sensor signal (although internally it is built differently).
"Manifold Absolute Pressure Sensor"
It takes a 5 volt signal from the computer, and returns a lower direct current signal in accordance with the vacuum in the engine. A higher production voltage means lower motor vacuum, which is then calculated as "more fuel is needed". Lower production signal indicates higher motor vacuum, which requires less fuel. It's not just fuel control though. The Map senor signal gives the computer a dynamic indication of motor 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 even used to reason changes in barometric pressure, to automatically adjust for dissimilar altitudes.
How Does The Maf Sensor Work?
The Mass Air Flow (Maf) sensor helps the computer to reason the flow and mass of the air entering the engine. It does that by measuring the cooling effect of air flow over a heated wire element. The electronic circuit inside the sensor attempts to keep the sensor at a fixed temp.
When it is cooled more by an increased air flow, more current is needed to contend a constant temperature. The growth in current is converted into a signal and that signal goes to the computer. In most cars this signal would be a high frequency signal. Not as high as a radio wave, but much faster changing than the (relatively) slow frequency of the Oxygen sensor.
During low air flow rates, such as at motor idle, the Maf sensor produces a lower frequency signal. During high air flow rates, such as at wide open throttle-road load, the Maf sensor increases the frequency. The control module then converts these frequencies into their corresponding Grams-Per-Second values.
Yet again, some Maf sensors may work on a level Dc signal 0-5Volts such as the typical Map sensor. This is the case in some older Map Sensor designs that have a trap door with a potentiometer linked to its shaft.
The Enhancer
The invention we're talking about here is a easy play with resistors. A resistor is a microscopic piece of carbon that somewhat blocks electrical current. Higher value means it resists more. The potentiometer ("pot" for short) is a resistor, a changeable resistor, which varies its value by turning the knob. But it is still only a resistor. There is other resistor, a fixed value resistor, in series to the pot as shown in the diagram below.
The Map or Manifold Absolute Pressure Sensor is a microscopic though costly gadget installed in your intake manifold, or installed on the firewall and linked to the manifold with a thin hose. It has 5 Volts or 12 Volts arrival in, and it naturally senses the vacuum in the manifold and attenuates (reduces, weakens) this incoming voltage by a determined factor. In other words it reduces the provide voltage to a direct-current voltage in the range of 15% to 60% of the provide voltage (depending on the car's manufacture these numbers will vary), and this varying (but non-pulsing) signal is then sent back to the computer.
The arrangement of resistors in the Map Sensor Enhancer naturally takes this already attenuated (reduced, weakened) signal - and attenuates it further. Too much attenuation kills the engine, it will naturally shut off. Yet if you control it correctly you can lean down the compound from the stoichiometric (a big word that naturally means "balance of ingredients") which is premise set at 14.7:1 (14.7 parts of air to 1 part gasoline) - down to 20:1, maybe even 50:1 or 100:1.
This gadget is totally passive and will work just the same if the signal arrival in is 12 volts, 5 volts, or whatever comes on the line. The diagram in the book is the Simplest way of doing this. The line from the sensor to the Ecu is cut, and you place a pot on the line as shown in the photo contained in the book. Additional below you will see the improved enhancer based on the same principle.
How Does a Map and Maf Sensor Enhancer Work? - Where to Look