Air Fuel Gauge

This is the 42643568th page you see on the internet! No but although it may be close to, this is some info about narrow band air fuel gauges. I have tried to collect some most basic info.
Air fuel gauges read, or monitor, the air fuel ratio though not in the accurate way as more expensive wideband gauges that give accurate readings which is required for performance tuning and they also need wideband o2 sensors. Narrow band gauges are cheaper.

An air fuel gauge needs an oxygen/o2 sensor and all cars since about 1980 cars already have o2 sensors built in so it is quite easy to connect an air fuel gauge. Narrow band gauges are cheaper than the widebanders and provide advantages as of below.

Air fuel ratio vs power/economy. New cars are calibrated no richer than stoichiometric to keep emission levels down.

Reasons to use an air fuel gauge

First, to check the o2 sensor itself. The o2 sensor is one of the sensors used by the cpu. If the sensor reads too lean or rich air fuel ratio it may be damaged, defective or worn out and it doesn't give readings properly. If it is not replaced some of the circumstances below may appear.

Without correct o2 sensor readings the catalytic converter may not operate well:

It may lead to :
- Increased exhaust gas CO2, NOX, HC emissions.
- The engine doesn't perform well and with decreased power.
- Bad fuel economy due to increased fuel consumption because the ecu are mislead by the o2 sensor. (yes there are other things that are important too in regards of lower fuel consumption, like the car's aerodynamics, the importance of not having heavy things in the car, but added altogether...).

Monitoring the air fuel ratio at turbocharging or supercharging

Forced induction engines go into richer air fuel mixtures and cannot handle lean mixtures for very long because the temperature may increase to levels where pistons and valves get destroyed. When boost gauges are used for this reason, an air fuel gauge can be a needed complement.

There are plenty of designs to choose from.

Different types

The most common air fuel gauges are the 2 1/16''- 52mm gauges. There are also 2 5/8'' - 67mm gauges. Some air fuel gauges are available with different gauge faces and different bezels. Being electronic gauges, there are led gauges, needle gauges, led display gauges and bar graph gauges.

The info below may not not include all air fuel gauges by each brand.
Shown in about half size if seen on 15'' 1024x768 or 19'' 1280x1024 monitors. These monitors have pixel size 0.297/0.294 mm.