air/fuel ratio install help

[KLR16V]

hi guys

ive just had a go at installing a autometer Air/fuel ratio guage into my mr2 aw11 4age.


Ive got a problem. i cant get it to work

The O2 sensor has four wires going into it and i have no idea which one it is that i put the signal cable from the guage into (the purple wire).

so i gave all the 4 wires a try to see if any thing seemed to happen and nothing really did.

- 2 of the wires made the guage do nothing
-1 wire made the guage work but only the last lean led was light up
-1 wire made the guage cycle up and down all the LEDs slowly and then when i opened the throttle it would shut down.


is the O2sensor where i am supposed to install the signal wire or is there some where else.


any help would be greatly appreciated

[oldcorollas]

the two same colour wires are for the heater... if you have connected 12V power to the gauge, it might now be fucked.

of the other two wires, one is ground for the signal. you can use a multimeter to check if it has voltage relative to ground. or check the resistance to ground when car is off.

the last wire will be the signal wire. since the O2 sensor is basically a switch, it will either read high or low, ie around 0.2 or 0.8V (or something liek that...)

perhaps, you should find out which of the two different coloured wires does not have continuity to ground, then connect that wire to multimeter and drive around....

the O2 sensor will most likely show rich all the time except when cruising.

[tai_180sx]

the autometer guage only read's air / fuel ratio's within a ceratain range. so you could have had the guage set up properlly but it may not necessarily show anything on the gauge at all.

i.e i'm cruising down the road (obviously cruise is very lean) and the guage basically turn's off. there are no lights on at all, but once i'm under power again the lights flash back up.

plus the other thing is that these guages aren't wideband or fast reading, so they aren't really helpful, more of just a guide as to whats happening.

[7mSupra]

You also have to wait untill the O2 sensor heats up for a few minutes for it to work.

[45aken]

"You also have to wait untill the O2 sensor heats up for a few minutes for it to work."
exactly correct.
plug it up and go for a good spin in it. the wrx takes between 2 and 8mins to heat up and read properly.

one thing though, it may look like you have hooked it up wrong, but the gauge actullay 'scans' when your not on WOT. flicks up from lean to whatever ur a/f is and back about once every 3 secs.

[oldcorollas]

if you have a 4wire sensor, it should only take 1minute to warm up at most, less if you are driving.

the "scanning" only occurs when the ECU goes into closed loop.
if you have aftermarket ECU with no closed loop, this won't happen

you can check you have not killed the gauge by using a AA battery and a pot and change voltage between 0.2 and 0.8 and see if the gauge reads normally

good luck!

[KLR16V]

Thanks heaps for all this help guys.

I tried all the 4 wires again.
And so decided to install the gauge into the only wire thats seems to have any sort of response.

When I start the car, the gauge LEDs will increase slowly from rich to stoich within about 30seconds.

However, after that there is not much action. 3 of the LEDs read stoich and only seem to only change to the next LED up or down. It doesn’t seem to bounce around from lean to rich nicely like I have seen on other cars before.

Then when I give WOT, nothing happens until 2500rpm when the very last rich LED lights up. And it is only until after the RPM drops below 2500rpm the gauge will read the Middle of the stoich part.

NOW THIS IS THE STRANGE PART!!!!!

The voltmeter gauge in the instrument cluster seems to bounce around like what the Airfuel ratio gauge is supposed to when the car idles.
And it also seems as if there is some sort of electrical interference in the gauge whenever I put my foot on the brake.

And OLDCOROLLAS

I will try your thing with the battery to see if the gauge isn’t buggered....
But I don’t think it is coz I can seem to make the gauge work when I squeeze the signal wire with my fingers.

Thanks again guys
Cheers

[oldcorollas]

hm, in an AE112? which had one of these installed, at idle, it didn't bounce around.. it was only cruising that it did stuff..

is there a sensitivity control on the gauge at all?


wtf, your cars voltmeter bounces around???

sound slike you need to double check the wiring!
and check that you have power and ground correct on the AFR gauge... etc etc..

if the other gauges are screwy, and stuff happens when you use brakes, then there is definitely a wiring problem

are you running stock ECU still? ie it has closed loop? what voltage are you seing on the signal wire to the AFR gauge?
multimeter will help heaps here

[45aken]

The voltmeter gauge in the instrument cluster seems to bounce around like what the Airfuel ratio gauge is supposed to when the car idles.

im out of this one!
way to freaky for me...