Edit: I just realized I put this thread in the wrong group

Each week I will add some great info, ideas and ways to tune your car for better gas mileage or even to get more power out of your old car.

In today's world of automobiles everything is computerized. People also pay big bucks to fine tune or try and get a few horsepower out from the motor. I am going to share ways on how to tune a car cheaply and only need to make a visit to radioshack or order from Digi-Key.

Controlling the fuel
This is a easy one and only costs about 9 to 10 bucks. All you have to do is modify the Manifold Absolute Pressure (MAP) sensor. Not every car has a MAP sensor. Some have Mass Air Flow Sensor (MAF), totally different sensors. Anyway, a typical MAP sensor uses 5 volts from the on board computer. If you increased the voltage the sensor will tell the on board computer to inject more fuel and the lower the voltage it will decrease the fuel.

When a car uses more fuel then air then the car is running rich and if there is more air then fuel it will run lean. Thing is it all depends on driving conditions. Some cars don't have a air temperature sensor so it can't tell the on board computer how much O2 is being sucked in on a cold day compared to a hot day. So on a cold day your car could be running lean. Well that is when you increase the voltage to the MAP sensor.

Now to do this you need a power regulator that will take 12volts and turn it anywhere from 1volt to 6volts. Too much voltage will cause the MAP sensor to blow and leave you stranded.
Heres a simple circuit for the power regulator. All of these parts can be found at Radioshack.

Part List
Multi-turn Cermet Potentiometer 1000 ohm
LM317T Adjustable Voltage Regulator
1/4watt or 1/2watt 220 ohm metal film resistor
Mini Terminal Strip or PCB board
Heatsink for Regulator
SPDT toggle switch
Speaker wire

In the circuit theres a kill switch so it shuts the regulator off to the sensor and switches it back to default voltage from the on-board computer for emergencies. Bellow is a diagram of the circuit. Remember all wire color codes are different from car to car. These days most car companies use what ever wire they have laying around to cut back on cost.

You can even tweak this so you can have a control knob inside the car for "on the fly" changes.

Next week we tackle the O2 sensors and some more air to fuel ratios.
To live is to let die