I was replacing my rear hood struts today, and I noticed that my O2 sensor wasn't connected. When I looked at the connection piece (the plug that the O2 sensor attaches to), it was broken.

My questions are:

1. What effect does this have on the engine?

2. How do I go about replacing that plug. I didn't get a close look at it, but my initial thought is to get one from a parts car and splice it on.

 

i spliced mine when i relpaced it...not sure if it works, but my car sure runs great

 

Matt:

Everyone has an opinion based on personal experience and IMHO, I think these cars run better in "open-loop"; oxysensor disconnected. I simply set the CO manually by pulling the little aluminum plug on the housing and use my special 3mm allen wrench.

Of course, this MUST be done with either a CO meter, a 4(5)-Gas analyzer, or a good AFR meter like the Innovate LM-1.

 

mine too is disconnected, I made a post about it a while ago, I still think it runs better than it did when connected, I drive it very little so I dont notice excess fuel consuption if there is any.

 

Hello Matt,

The O2 sensor only comes into play above 95F and below 35 % throttle. It can only have a fantasy effect on WOT performance. As long as the control unit and frequency valve are operational, the engine will run OK on the default settings. If you still have a catalytic converter, it's life will certainly be reduced, in direct proportion to the fueling error below lambda. The HC and CO emissions will likely be higher, no engine management system can supply a constant lambda, they all need an O2 sensor to dither the mixture to establish an average. The idle may be more stable without the cycling. Your fuel mileage will also likely drop. You should hook it back up for the sole reason you can then see how the frequency valve and control unit are working with an analog dwell meter. Then you can disconnect it, if it makes you feel better.

Paul

 

My '81 "seems" to run better with it hooked up, but maybe not as Steve Weiner and John Walker both say that SC's run better with them unplugged, and they are the gurus. Think I'll unplug mine again and leave it that way for a while and see how it does.

 

Being in CA, I had to have all my customer cars with oxy sensors hooked up and functioning correctly - yes, our state inspectors know what to look for at smog cert time! I agree with Steve regarding '80/81 models, but I feel that little/no difference exists on '82/83 cars. The first Lambda cars had a tendency to surge slightly under light, steady throttle with the oxy sensor hooked up, and not surge with it disconnected. By '82 we no longer felt this. We spent many hours trying to eliminate the light surge, by setting CO% at different points within the factory stipulated range, but were never successful. The surge was there, and part of the car. We only had a couple owners ask us about it, nobody really complained, but it kind of bugged us. But, like I said, in CA the car has to pass smog every two years so we let it be.
Pete

 

So assuming I want to connect it, where could I get the connector piece that the O2 sensor plug attaches to?

 

arbeitm, I believe Draco had a post about replacing the O2 connector. Is yours the hard yellow plastic one? These break, and depending on whether the original wire is broken or not, you can either fix it or replace both sides of the connector. I found that you have to use a crimp on connector.

My buddy's '82 SC from hell, the one that I'm always being asked to help fix, runs ok without a functioning O2 sensor. I used my LM-1 to adjust the mixture, as Steve pointed out.

 

Wow this is an old thread you brought back.

I had ended up buying one off someone who was parting out his car. He cut it off and I spliced it on with a crimp connector as you stated. It's a bit of a pain because the wire has ground wires wrapped around it to prevent it from catching other signals. So you have to make sure those don't get mixed in the splice connection.

I ran the O2 sensor unplugged for a long time. A few months ago I adjusted my CO mixture to spec (with a Gunson) and plugged the sensor back in. I can't say for sure it's working though. I suspect it's not. My next project is to start going through the CIS and get everything running right.

But I have a few things to do before that.

 

man Rusnak must be bored ... this stuf is seeping out of the archives now ..

 

oh wow, I didn't check the date.

It showed up at the top of the page when I clicked the 911 forum link. Rennlist website snafu?

 

Weird. I was wondering why you responded to this.

 

who are you guys? What year is this?

 

I have gt3 997.2 and i use FabSpeed sport headers cat less .. so I have problem with the mixer how can I solve the problem