O2 sensor - signal wire...

[Rodd1s]

on the o2 sensor on the 8v engine, it has 2 wires.... purple and a strange orangey one. which one is the signal wire? is it the purple one which goes in to the body of the sensor, as opposed to the orange one which is attached to the outside of the sensor like an earth strap.

just thought i'd double check before tapping into the wrong wires.

[Rodd1s]

anyone...? no?

well i'm gonna go for the purple wire.

[Big Jeff]

on my 1.6 ecu diagram is says it is purple, so i would think its the same for your 1.3

[Rodd1s]

yep, its the purple wire, but then i run into some trouble...

wired up the air/fuel ratio gauge, which didnt give any readings until the the engine (and presumably the o2 sensor) had started heating up. once it did warm up it showed a reading on the line between lean/optimal, gave it a little rev and this did nothing. then the needle slowly started falling into lean followed by a shitty idle and the engine almost cutting out. this went on for about 20 seconds before somehow the engine jumps back into life and goes to normal idling for about a minute and then the same happens again. turned the engine off, tried starting it up again, but nothing. tried again with my foot on the throttle and pumping it and it started but with the realy shitty idle.

turned it off again, disconnected the air/fuel gauge and it started 1st time, had bad idle for 10 seconds before correcting itself and now its fine - with the gauge's signal wire disconnected.

anyone got any ideas as to why this could happen? or whether the air/fuel ratio gauge could affect the o2 sensor's output to ecu?

[Big Jeff]

in general the O2 senser don't start working till till the engine is warm..

[Rodd1s]

in general the O2 senser don't start working till till the engine is warm..

i know, but even after its warmed up it was giving a weird reading at idle, i expected the needle to jump back n forth.

and something about the gauge was making the engine idle badly. once the gauge was disconnected from the o2 sensor the engine was fine realy.

[Rodd1s]

can anyone provide any insight as to why or if an air/fuel ratio gauge could alter signals between the o2 sensor and ecu in a way that it'll alter and generally screw up the engine idle?

i'll connect it again tomorow and see if it still happens in case it just had a bad mood swing the first time round.

[Big Jeff]

not sure why...

it could be as short in the wire same where or a naff gauge

[PrecisionBoost]

First off.... I hate to tell you this but a regular old Daewoo O2 sensor will tell you absolutely nothing.

There are narrow band and wide band sensors.... the narrow band being the cheapest and therefore the one 90% of car manufacturers use.

Think of narrow band more like a switch.... it jumps from lean to rich to lean to rich.... that is to say it can't really tell the difference between 14.8:1 or 16:1 it will simply tell the ECU that it's lean... and again with rich it can't tell the difference between 14:1 or 8:1.... it will simply tell the ECU that it's rich.

The ECU will simply let it go lean.... add fuel... let it go rich.... decrease fuel.... let it go lean....add fuel..... and so on.

Basically a narrow band O2 sucks.... the ECU is always guessing as to what it thinks the air fuel reading is by watching the narrowband O2 switch back and fourth

A wide band will change voltage in correlation to the actual air fuel ratio... and this is the only type of sensor you should be using with a Air-Fuel gauge.


Now.... as far as your car idling funny.... the Gauge is most likely changing the switch point voltage and screwing up the ECU.... I would disconnect it immediately and never hook it up again.

If you really want to know Air/Fuel you need to spend a couple hundred dollars on a wide band system... I like the ones made by Innovate motorsports .... I have the LC-1 and like it because of all the features and reasonable price.

http://www.innovatemotorsports.com/

[wolfsreign]

im with precisionboost on the wide and narrow.

if i understand the o2 correctly.. its Ohm readings.. meaning the orange would be a ground and purple would be +, your signal. so as it gets hotter it is more Ohm's thus telling the ECU. i think thats correct, well so if measuring resistance and you add more wire to the reading, meaning more resistance.. it then give the ECU the wrong signal. >.<
~wolf