I was going to say "Do a search, noob", but I did a search on this forum and didn't find much. So here you goOriginally Posted by http://www.superchargersonline.com/content.asp?ID=127The A/F gauge will measure the air to fuel ratio that is being burned in your combustion chamber, or in other words how lean or rich you are running. The air/fuel ratio is the ratio of Air to Fuel drawn into the cylinder. The optimum ratio of Air to Fuel is about 13.5-pounds or air to 1-pound fuel.
There are Narrowband and Wideband Air/Fuel gauges available. A Narrowband does not provide the precise Air/Fuel reading needed for tuning. The Narrowband will meter the output of voltage from the vehicles oxygen sensor through LED lights.
* Narrowband Air/Fuel Gauge
The Narrowband Oxygen Sensor cannot indicate what exactly the A/F ratio is in the rich or lean areas due to the fact that oxygen sensor output changes with temperature and wear. When the oxygen sensor temperature increases the voltage output will decrease in the rich area, and it will increase in the lean area
* Wideband Air/Fuel Gauge
A Wideband Air/Fuel gauge is better suited for tuning. These gauges will provide an accurate reading of the Air/Fuel ratio. The wideband sensor provides a signal thatís virtually proportional to the amount of oxygen that is in the exhaust stream.
A wideband Air/Fuel gauge is by far one of the best investments tools you can have when dealing with tuning. This will allow you to have a full accurate reading of your Air/Fuel mixture. If your Air/Fuel ratio is lean, you can blow your engine. This gauge will help you achieve accurate readings so that you will have the proper Air/Fuel levels so you can enjoy peak performance with engine longevity. Click here for all Air/Fuel and wideband gauges.