When tuning up a motor one of the most important aspects to check is the air-fuel ratio. This is the quantity of fuel you are going to combust for a given amount of air. For regular pump gas you can go through the chemistry and work out the stoichiometric point and that comes out to be 14.7:1. This is where you'll have complete burn. A number lower than this shows you are running Rich, higher indicates a lean condition.

So just how can you tell where you are on the air-fuel ratio scale, well, you can use a device called a O2 sensor. This device works by measuring the quantity of oxygen left over in the exhaust gas after it passes through the motor.

There are two main types of O2 sensors, them being a narrow band O2 that most production cars come with and a wideband O2, that is heavily used in the auto motive after market for tuning air-fuel ratios.

The narow band O2 is essentially that, it has a very narrow band of which it reads accurately. In fact, that range is so small it's almost just a switch and can essentially be thought of that way. While not getting into detail about the inner workings of engine management systems, the narrow band O2 essentially tells the ECU either to add fuel or take away fuel depending on which side of the switch it's on. Just where does that switch point happen to be, well, it's at the 14.7:1 as mentioned above. While this does a good job of telling you if your car is running rich or lean, it doesn't accurately tell you how rich or how lean.

This is where the wideband O2 steps into the picture. It has a broad range of measurement and can accurately tell you where you are sitting air-fuel wise. Why is this such a good thing, well, in order for a car to make good, safe power you want to run it a little on the rich side of things. For example a typical turbo car will operate best running at an air-fuel ratio of approximately 12.3:1. On the narrowband O2 you'd have a hard time finding this point, but with use of a wideband O2 you can accurately read where you are. It's the best way to get air-fuel ratios sorted out and you'd be surprised at the difference in power a properly tuned motor will have.

If you're looking for wideband O2 sensor I would recommend looking into FJO Racing's Wideband O2 setup. It is probably the toughest built and most robust one on the market today. You can also check out a review of it on our site. A couple other top notch wideband O2 controllers are from tech edge, AEM and Innovative.