rks275

Hi,

I have just fitted an air/fuel ratio gauge to my late 97 impreza, (it has the ecu with 3 yellow connectors)

I am 99% sure that it is wired into the correct wire (pin5 on connector B136 a blue wire)

When i'm accelerating the gauge displays information fine, and sits borderline on Stoich/Rich but when im backing off/coasting or letting the engine take the car, the gauge moves around on the stoich section but it also drops right down to the bottom of the scale and the gauge will display nothing sometimes for seconds and other times it comes straight back up.

Is this normal behaviour? as its not a wideband gauge or lambda? or is it signs of an additional fault? possibly with the gauge or possibly a faulty lambda?

Once I can find a multimeter I will test the wiring with this, lamdba reading are between 0 and 1 volt?

any help is appreciated

rks275

have checked the signal going down the wire and when the gauge drops off the voltage is going down to -0.04 - -0.06

so it looks like the gauge is working correctly, is this normal for the lambda to be giving such a signal?

Coffin Dodger

Sounds normal to me, if you're in gear, and the throttle is completely closed, then the ECU should cut the fuel supply completely. There will only be air going through the engine hence no CO reading from the lambda. Once the revs get below a certain point it will add a little fuel to stop it stalling.

rks275

thats exactly what I wanted to hear

thanks mate

harvey

iTrader: (48)

As indicated above, on the over run above 1700-2000 rpm, depending on model and ECU, there is little or no fuel going into the engine so the NARROW band sensor is off the scale, lean as it cannot measure the very weak mixture.
What make of guage is it?
If you are on a level road or slight down hill and let the car over run with your foot off the throttle, as the rev counter drops down between 2300-1700 (certainly on a Classic) you will feel the injectors start to fuel again as the engine is now supplying enough fuel to tick over and there is a slight reduction in engine braking/retardation.