Green O2 sensor wire
 

My old O2 sensor on the 83 ist kaput. The classic connector disintegration problem.

So I bought a PLX wideband O2 sensor and AFR gauge setup. I got the new sensor in and I'm wiring it up today.

The PLX has a narrowband output that I can feed into the ECU.

Here's the question: Can I just snip the end on the green wire -- the crumbled male end -- and patch the narrowband output directly to the green wire?

Seems like I recall something about a wire being shielded with a ground but I can't remember if that's the O2 sensor wire or the green wire.

Any takers?

My '84 has the green shielded harness wire that had to be stripped back to get at the core wire. IIRC you don't want the shielding to contact the core during connection of the new male end. If you do a search under O2 sensor my thread from earlier this year should come up with links in it to other threads.

Edit: http://forums.pelicanparts.com/porsche-911-technical-forum/733292-3-2-oxygen-sensor-issue.html

I remember Grady Clay talking about the ground shield on the green wire and if you leave the "hot" wire exposed (without ground shield) you may experience radio interference.

Our (later SC) 02 sensors are one simple wire that transmits the wee bit of voltage to control the Lambda box / frequency valve. No shield on the O2 wire.

Take refuge (not trying to cause problems here) in the fact that you do not have a girly-man multi-wire O2 sensor.

Also, why don't I have any friends?http://forums.pelicanparts.com/suppo...boldyellow.gif

BE911SC, I wonder if there is a meaningful difference from 83 to 84 to matter regarding the sensor wire. So much is different with Motronic.

Bob, you tell it like it is. That's why we like you. :)

There are two wires going through the firewall - the wire to the male end of the sensor and the wire to the test port.

I need to wire the narrowband output of the PLX box to the the broken wire. If I just cut the broken end off, I think I can just crimp the narrowband output to that wire. Sound right? I have read conflicting things... Solder it. Don't solder it. It's shielded. It's not shielded. I'm confused.

Here's a few pics...

The old original O2 sensor
http://img.tapatalk.com/d/13/09/29/6uzu8ade.jpg

The old broken connector
http://img.tapatalk.com/d/13/09/29/uqaze5e4.jpg

The new wideband sensor
http://img.tapatalk.com/d/13/09/29/uhuqu6y2.jpg




Sent from a tiny screen

Your sensor and the broken piece look exactly like my '84's. Bob says no shield on your green wire so it should be easier to fix. If you look in my thread you'll see member Louie85--he made the nifty replacement for the broken upper/male/harness end of the O2 connection. I PM'd him and had one in a week or so.

I am sorry. I am thinking of "THE GREEN WIRE" from dist to the CD box. That is shielded but is not the issue.

The 83 wiring diagram shows the wire from your broken connector to the Lambda box IS shielded. Center goes to terminal 2 and shield to terminal 4 on the box.

I see no issue with you tying into the core wire without cutting it. I would JB weld your broken connector or get a new one as BE911SC suggests. Attach the old female connector to the narrow band wire. This is voltage driven, not resistance. I don"t see how a good solder joint would impact anything. All the core wire does is transmit the less than one volt reading from the O2 sensor to the Lambda box.

All of this assumes that "narrow band" is basically what the old O2 sensor is. I don't know that for sure.

You can test the new narrow band output with a voltage meter after it warms up to make sure it is in that one volt range before plugging it in. Then there is no risk you will harm the box. If you know that narrow band is what the old O2 sensor is, skip this test.

http://www.pelicanparts.com/911/911_Parts/Electrical/911_electrical_82SC_Part6-1.jpg

http://www.pelicanparts.com/911/911_Parts/Electrical/911_electrical_82SC_Part6-2.jpg

Thanks, guys!

Bob, I really need to find one of those laminated color wiring diagrams for the '83. It sure would be easier in the garage.

I wonder if pin 4 is just acting as a ground wire?

Maybe I should check with Louie and get one of his replacements. What you can't see in the pic is that the wire inside the crumbled connector is frayed and is barely hanging on for dear life.

Now I have to figure out whether to mount the PLX box next to the CDI or under the passenger seat next to the ECU. Seems like I need the long wires that came with it to be shorter and the short wires to be longer. Figures.

Thanks again for the help!

From Wiki

The shield acts as a Faraday cage to reduce electrical noise from affecting the signals, and to reduce electromagnetic radiation that may interfere with other devices (see electromagnetic interference)

The common method to wire shielded cables is to ground only the source end of the shield to avoid ground loops.

Shielded cable - Wikipedia, the free encyclopedia

A-ha! Thanks, Bucky! Er, I mean, Bob! :)

For the record, JB Weld didn't hold when I tried it on my broken connector. I think my choice was to get a new factory wiring harness (with the O2 connector) or go with Louie85's nifty replacement, which I did. Not a lot of excess green wire to work with so if you use Louie's replacement make sure to snip the old one as close to its body as possible. I had maybe three inches of green wire and with some patience we got it connected and back in fine working order.