02 Sensor relocation

[Quint]

The 02 sensor used to be located at the factory collector about 100mm from the turbos.

Now the current sensor wont reach where it needs to be located (at the collector, 304.8mm from the turbos) so the obvious choice is to lengthen the wires, however from my understanding the sensor works on resistance, will increasing the length of the wires, which will increase the resistance (of the overall unit), effect the sensor and its readings in any way?

[mr30%jr]

no

o2 sensors output a small amount of voltage not resistance.

lengthening the wire is fine just bear in mind its a shielded cable and if you extend too far without more shielded cable it could pick up noise...

[Quint]

^^ Thank $&#$% for that, already moved it. hahaha.

Hardest part is going to be stopping a rock from tearing it from the collector. *sigh* time to weld up a scatter shield.

[kim0663]

just curiosity but wouldn't the change in resistance from lengthened wires be enough to alter o2 sensor voltage output?

as V = A x R or voltage = current x resistance?
and voltage of o2 sensors i thought were below 1V was it around 0.3 to 0.7 ...?

Only scenario to make mathematical sense would be when lengthened wires don't increase resistance.

Maybe i just answered my own question here

[sergei]

In general it does not matter exactly what voltage is on Oxygen sensor (narrow band).
As the ecu looks at it if it is above or below threshold (0.45V from memory), if it is 0.6 or 1.2V it will register as high. To have that huge voltage drop with 16AWG you will need huge length of it (kilometres), 2.68 Ohms per 100m, so if you increase it by 1m the resistance will increase by only 0.0268Ohm. without know how much current goes through there it is difficult to estimate the voltage drop of that run.
Lets assume the input resistance of ECU is 10kOhm (normally I would assume mega ohms = opamp input, but lets make it worst case scenario), so 1.2V@10kOhm works out 120uA, so drop will be 3uV for 1m of 16AWG (0.000003216V).