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Understanding the benefits of MAP - Technical

To understand how a MAP-sensor works and what advantages it has over the standard Air Flow Meters (AFM) that came on our cars, or even upgraded Mass Air Flow meters (MAF), we have to examine how these devices generate a volume-air-flow signal to the Bosch Motronic computer (DME).

AFM - air-flow meters are the crudest form of sensing devices. It uses a mechanical flapper barn-door that is physically pushed aside by the intake air stream. The volume of this air-flow then determines how much the door opens. The door then is mechanically attached to a variable-resistor assembly that then sends a variable-voltage signal to the computer that roughly correlates to the volume of air flowing past it. However, there are some disadvantages to this method:

MAF - mass-air-flow sensors replaces the mechanical measurements of the AFM with an electronic version. MAF-sensors use active analogue electronics to measure current flow through a heated wire placed in the air-stream. As air flows past the heated wire, it cools the wire, with more air cooling the wire more. The circuit then pumps more current through the wire to keep its temperature constant, with more current required for more airflow. This current then drives an output voltage to the stock computer. One nice thing about the MAF-sensor over AFM is that air-temperature and pressure compensation is automatically included in the output signal. Denser/cooler air will cool the hot-wire more, and a higher voltage will reach the computer to indicate larger numbers of molecules flowing into the engine. As good as this is, MAF-sensors also brings along with it some of the same drawbacks as AFM-sensors and adds some new ones of its own: MAP - manifold-absolute-pressure (also known as speed-density) measurements combine simplicity in sensor design with the power of digital microprocessors to compute a simulated volume-air-flow signal that is sent to the stock computer. As shown in the following diagram, you can completely replace the entire stock AFM-sensor (or upgraded MAF-sensor) and their associated wiring with a simple vacuum hose. As far as the stock computer's concerned, it's seeing the signal from an actual stock Air-Flow-Meter. Thus the computer will inject the appropriate fuel-volume to produce the highest power possible. This MAP-sensor upgrade kit doesn't suffer from any of the drawbacks of AFM- or MAF-sensors and has some unique benefits as well: Note that this isn't a piggyback-style signal-interceptor/massager like the Split-Second ARC-2, Apexi AFC, HKS AFR or the UNIchip. Those units sit in between the stock AFM or an aftermarket MAF sensor, intercepts and massages their outputs to fool the computer into thinking air-flow conditions are something other than what they really are, thus the computer is tricked into injecting less or more fuel to compensate.

The AFM-Link box (used in ProMAX MAP kits) is the actual sensor itself that generates (from scratch) an actual air-flow signal to the computer, rather than simply intercepting and massaging an existing signal from some other source.

Due to its advanced digital micro controller-based design, the AFM-Link fuel-computer is a fully self-contained unit that includes a MAP-sensor and the digital electronics to compute a simulated air-flow signal that closely matches ANY and ALL actual flow conditions. It can create non-linear discretely mapped fuel-curves to give you precise fuel-metering under all conditions.