air/fuel ratio gauge

[scooby999]

I have one of these fitted to my car,it has 3 setting lean(red),stoich(yellow),rich(green).
When i start the car it sits in the stoich(yellow)setting and as i drive it drops into lean(red) and keeps droping right the way down to the bottom.Reading the paper work it is susposed to start in stoich and move to rich as you boot it.
Does anyone know how i can get it to run in stoich
http://www.egauges.com/pdf/AutoMeter/837j.pdf this is the paper work for it

Also i have no idea what stoich means does anyone

thanks Jason

[Anger]

I ripped my one out of the RA as it was annoying me, saying it was lean one min Rich the next... But was mapped perfect

[Scott.T]

check the gauge connection to the lambda signal is ok and that the power and grounds are good.
If ok it is likley to be a faulty lambda sensor. When warm the sensor should rock between 0.3 and 0.6 volts. This is equal to stoich.

You will probably find it is stuck around 0.2 volts.

The ECU is trying to maintain an AFR of 14.7 / Lambda 1. This is why it rocks too and fro. too rich and the ecu removes fuel, too lean and it adds fuel.
Once you go above approx 3200rpm or achieve greater then 0bar boost i.e no longer a vacum, the ECU switches from using the Labmda sensor and 14.7AFR to using the MAF. Fuelling at the top end on a stock WRX would be around 10.5AFR

These AFR gauges are only for peace of mind, they should not be relied on or mapped with, as the sensor in the car is only a narrow band.