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Below is a circuit for the MAP sensor and should work on most MAFsensors that are voltage based. I am not sure where I got this but whomever it was I am thankful. I works very good and is really simple to build.

Parts are from Radio Shack

Parts List

  1. Multi-turn Cermet Potentiometer 1000 ohm
  1. LM317T Adjustable Voltage Regulator
  1. 220 ohm metal film resistor
  1. Small project box
  1. Small perf board
  1. Heat sink for Regulator
  1. SPDT toggle switch

I ran my hookup wires directly to my board connections and soldered.
I then Tied a knot in the wires and ran them through a hole in my project box and sealed it with silicone.
Mounted the box under the hood with a big dot of silicone.

The switch allows you to toggle between the factory 5.0 volt input and the adjusted input that you dial in. In case something were to go wrong with this MAP adjuster you could easily switch back and not be stuck somewhere. You could also eliminate it and use bullet connectors on the wires and just unplug the MAP output wire and connect it back factory mode till you can make repairs on your Adjuster.

The MAP sensor voltage adjuster has five wires:

*5.0v from wiring harness to left terminal of switch
*MAP sensor input from middle terminal of switch to MAP sensor
*Adjusted voltage from voltage adjuster to right terminal of switch (internal connection on board)
*12v supply to voltage regulator
*Ground wire from variable resistor (pot) to firewall
This is one I made.
Map Adjuster

Back side of board
Bottom View of Map Adjuster

Adjustment of the voltage from the adjuster is easy. Just hook up the positive lead from a digital multimeter to the adjusted voltage terminal and the negative lead to the ground. Read the voltage and adjust as required. Stock MAP sensor input voltage is 5.0v. If you turn the voltage higher than that, the air/fuel mixture will be enriched. If you reduce it to below 5.0v, the air/fuel mixture will be leaned.

Map Schematic

 

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