O2 connection wire...

[clev]

Well if you've been following my posts, the car wouldn't start last night nor this morning, but I went out about half hour ago, and it started right up and purred like a kitten. I started going through wires and connections, and the male part of the O2 plug came off in my hand. I'm going to have to adapt the blade to go into the female part, but when I skinned the wire, it's like television coax and has braided wire around the inner wire. What do I do with the braided wire? Should I make a connection to a ground? I'm right in the middle of this and need a quick response, if possible. Thanks,

Clev

[dahodges]

O2 is a one wire sensor (regular wire). Are you sure your dealing with the O2 sensor? Is this the sensor that goes into the exhaust?

David

[jglutz]

How many wires on the engine harness side of the connector? Should only be only one....that's all the ECU can handle.

You most likely have a near aftermarket installed.

Connect to the center wire and give it a whirl...you cann't damage anything.

[FB71]

yes, the outer conductor is a shield. It does not need to be grounded. Also, the O2 sensor does not affect starting. It only trims fuel delivery after the engine is warm.

[clev]

Come on guys/gals, I know I need help with this ignition problem, but give me a little credit. I know what an O2 sensor is, what it looks like, and how to ID the wire.

Thanks FB and although it does not need to be grounded, can you tell me its purpose?

Another question, while the car was running, I was using my digital volt meter (or trying to), to check a couple of circuits (volt setting) and with it anywhere near the engine, the digital read out was going crazy; down to '1' like checking ohms, up to 19v, down to 0 ~ 12v, and various other reading; the probes were not connected to anything. Is that normal for a digital to get interference from a running engine or do I have electrical current jumping around the engine?

[FB71]

hmmm... that tells me you have significant RFI generation (Radio Frequency Interference). You didn't happen to use solid core ignition wires, did you? One of the things I teach my students is about stray or 'ambient' voltage. Thinking back to elementary school science, magnetic fields crossing thru a conductor generates an electrical current in that conductor. By allowing the two meter leads to hang free, RFI (magnetic gauzz fields) transitioning thru the leads causes the meter to show this 'stray' voltage.

Now, the above description of stray voltage is exactly why the O2 sensor wire has a shield. The outer conductor is already grounded to the sensor body, so it does not need to be connected to another ground (potentially causing a ground-loop). This grounded shield wire collects stray voltage, and prevents it from causing a false signal on the O2 wire.

[jglutz]

Thinking back to elementary school science, magnetic fields crossing thru a conductor generates an electrical current in that conductor.

I'm impressed....your a genuine Michael Faraday or Carl Friedrich Gauss!
This stuff is great!!!!!!!!!!!!

[FB71]

[bowing] Why, ah-Thank You!

[clev]

hmmm... that tells me you have significant RFI generation (Radio Frequency Interference). You didn't happen to use solid core ignition wires, did you? One of the things I teach my students is about stray or 'ambient' voltage. Thinking back to elementary school science, magnetic fields crossing thru a conductor generates an electrical current in that conductor. By allowing the two meter leads to hang free, RFI (magnetic gauzz fields) transitioning thru the leads causes the meter to show this 'stray' voltage.

Now, the above description of stray voltage is exactly why the O2 sensor wire has a shield. The outer conductor is already grounded to the sensor body, so it does not need to be connected to another ground (potentially causing a ground-loop). This grounded shield wire collects stray voltage, and prevents it from causing a false signal on the O2 wire.

FB, I'm learning more everyday; thank you and all the others that's offered advice.

Now, a couple of things:

I have 8MM Accel (yellow) s/plug wires; not sure about the solid core, but will check.

The outer shield on the O2 wire is no longer connected to anything; I broke the wire. I wired the main, center wire to a blade and reinstalled it in the O2 female end and taped it extremely well, but the outer braid is no longer connected, so it is not grounded to the sensor body. Should I splice in a wire from the braid to the sensor body?

[FB71]

it should be grounded to the sensor body inside the sensor. If you want to verify, set you meter to ohms and check continuity between the shield wire and the sensor body. Only ground it if it shows no continuity.

[clev]

I've already checked the continuity; there is none with anything. So, should I splice in a ground wire to the vehicle body or splice in a ground wire and somehow (solder) it to the body of the sensor?

[FB71]

you can tie it to chassis or engine ground.

[kzbill]

I did the solid core wire thing, it took months to diagnose the problem. stock wires fixed the problem in five minutes.

[kned33]

I wonder about the comment up above about the o2 sensor not affecting starting. If the sensor fails and engine runs way to rich could the engine become flooded thereby making it more difficult to start.

[FB71]

the pcm won't send the mix that rich based on the O2 signal. The actual range of adjustment based on the O2 is actually quite narrow, not enough to cause fuel fouling. Fuel fouling would have to be caused by something much more dramatic, like a stuck open VAF or injector.