O2 Sensor Wiring Question

[therex]

So my o2 was wired in with radio wire so i decided to replace it, I know that the o2 sensor coming from the harness is the thick grey/black wire, so I wired it in no problem, ran great, then is started popping fuses (the EGI comp 30A) so i rewired it again and its still doing it.

Ive heard something about theres two different wires of something and im confused. Just wondering if someone could clarify on how to properly wire it.

Thanks!

[therex]

for an s4 motor

[RETed]

For stock wiring...

The wire is actually a shielded wire with a single, center conductor.
The center, stranded conductor is connected from the O2 sensor (actually the plug) and snakes all the way to the ECU.
The braided shield wire is bundled and grounded only on the ECU side.
Do not ground the other / engine side of the braided shield wires.
Also, do not allow the strands from the braided shield wires to touch the center, stranded single conductor wire.


-Ted

[therex]

Originally Posted by RETed

For stock wiring...

The wire is actually a shielded wire with a single, center conductor.
The center, stranded conductor is connected from the O2 sensor (actually the plug) and snakes all the way to the ECU.
The braided shield wire is bundled and grounded only on the ECU side.
Do not ground the other / engine side of the braided shield wires.
Also, do not allow the strands from the braided shield wires to touch the center, stranded single conductor wire.


-Ted

ok so i just wired it with regular electrical wire, do i need to use a special wire? and i can just crimp everything back in right?

[therex]

ok i see it, so crimp the conductor wire to the wire going to the o2. doe the braided strands need to be touching anything? or do they just sit there

[RETed]

It really doesn't need to be anything special wire...

On the engine side, the braid shield wires should not connect or touch anything.


-Ted

[therex]

Originally Posted by RETed

It really doesn't need to be anything special wire...

On the engine side, the braid shield wires should not connect or touch anything.


-Ted

i did that its not touching anything and it just blew another fuse...

[RETed]

Then it looks like your problem is elsewhere other than the O2 sensor and it's wiring...

The O2 sensor generates a tiny voltage (versus the chassis 12VDC).
This is the reason why it uses a shielded wire.

Sometimes people tend to ground the braid shield wires on the engine side, and this creates a "Faraday Cage" effect and screws up the O2 sensor signal.
The only downside is that your mileage suffers slightly, as you just screwed up the O2 sensor closed-loop fuel system.

If you happen to connect +12VDC to the braid shield wires, you get an immediate short, and you get lots of spark and possibly a fried wire.

If you happen to ground the center O2 sensor signal wire, you could possibly damage the O2 sensor itself.

If you happen to connect +12VDC to the center O2 sensor signal wire, you can fry a portion of the stock ECU electronics.
In mild cases, you just killed off the O2 sensor closed-loop fuel system - see above.
In serious cases, you fried the entire ECU and the car will not start / run.

None of it goes through any fuses, unless you blew the "main" fuse and the car doesn't start or run?
Which fuse are you blowing?


-Ted

[therex]

Originally Posted by RETed

Then it looks like your problem is elsewhere other than the O2 sensor and it's wiring...

The O2 sensor generates a tiny voltage (versus the chassis 12VDC).
This is the reason why it uses a shielded wire.

Sometimes people tend to ground the braid shield wires on the engine side, and this creates a "Faraday Cage" effect and screws up the O2 sensor signal.
The only downside is that your mileage suffers slightly, as you just screwed up the O2 sensor closed-loop fuel system.

If you happen to connect +12VDC to the braid shield wires, you get an immediate short, and you get lots of spark and possibly a fried wire.

If you happen to ground the center O2 sensor signal wire, you could possibly damage the O2 sensor itself.

If you happen to connect +12VDC to the center O2 sensor signal wire, you can fry a portion of the stock ECU electronics.
In mild cases, you just killed off the O2 sensor closed-loop fuel system - see above.
In serious cases, you fried the entire ECU and the car will not start / run.

None of it goes through any fuses, unless you blew the "main" fuse and the car doesn't start or run?
Which fuse are you blowing?


-Ted

Ok i see what your saying. Its blowing the egi comp fuse, the 30amp one and it never blew before, only when i put the new o2 in