hi all, i have a 95 wagon with a apexi t-timer with a afr monitor. i understand that this uses the lamda signal voltage. when the sensor is hot the voltage jumps around from 0.88 on boost and down to 0.08 on idle. when accelerating gently i am getting lamda voltage around 0.65 but this only gives afr 14.4 on the display. my worries are that i am running very lean, even though the lamda voltage sometimes goes upto 0.9 which i thought was the max and so means a rich mixture but the display never goes below 14.0 can anyone explain how the lamda works with the ecu to keep the afr within limits. cheers all.

 

Air-fuel ratio (AFR) is the mass ratio of air to fuel present during combustion. If exactly enough air is provided to completely burn all of the fuel, the ratio is known as the stoichiometric mixture (often abbreviated to stoich). Lambda (λ) is an alternative way to represent AFR.
Any mixture less than 14.7 to 1 is considered to be a rich mixture, any more than 14.7 to 1 is a lean mixture ..

so 14.7 is perfect lamda

 

but coz its a 95 it should have the other system on it , Zirconia type Lambda sensor

The larger the difference in the oxygen readings the larger the signal voltage. The sensor can be a 0 to1 volt or inverted as a 1 to 0 volt. The voltage will fluctuate between 0.2 and 0.8 volts when operating correctly.
In a 0-1 volt sensor 0.2 volts would be a lean mixture and 0.8 volts would be a rich mixture.

 

thanks for the reply, i understand what afr is but was asking why my lamda is giving max signal voltage as it should when under boost conditions but the display is only showing 14.0. i thought it would show the afr to be around 11 or 12. should i ignore the displayed afr as it is only a guess the monitor is making? how can i check the actual afr or do all guages/monitors take their input from the lamda? if so they are only as good as your o2 sensor.

 

was typing as you sent your second post, cheers.