1980 O2 Sensor
 

Will a bad O2 sensor cause the car to run rough, or make throttle response less than desireable?

1980 911SC

Yep...

My O2 sensor is disconnected from my 82 SC ... runs better without it now that the fuel mixture has properly been set.

can you just unplug it at the connection in the engine compartment to see if that is causing the problem?

yes, you can disconnect it there. i was getting some subtle hesitation and a rough idle - disconnected it in engine compartment and everything ran smooth after that.

I disconnected and it ran well, but changed the O2 sensor and it ran even better. I personally prefer an O2 sensor installed.

carreras are different animals. SCs run better without it, IMO.

1980 911 O2 Sensor
 

Well, if you look at all the post I have made regarding my 911 running rough I think I have found the problem.

After d/c my O2 sensor I started the car. It still ran rough. Then I heard a click under the passenger seat and it ran good. I heard the click again and it ran bad, one more click and ran good. Next to the computer is the O2 sensor relay. When I unplugged the relay it ran bad again showing the same symptoms. Went to Kragen bought a $6.00 universal relay. Runs great.

It only took me 3 months and around $1000.00 in parts to figure out is was a $16.00 OEM $6.00 am relay.

replaced: Plugs, wires, fuel filter, alternator (needed), cap and rotor, installed new MSD 6A, new coil, ignition switch (needed), air filter. etc....
These parts were probably all needed anyway!

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thanks

quick question: is ok to change the sensor every 30K? and where is the sensor? any pics that shows where to find it? :D

I am going crazy trying to follow the exaust line on the bottom of the car :P

Thanks!

There's a light in your dash in the (speedo? tach?) that says OXS that lights up every (75K?) miles to remind you to replace the O2 sensor. It's not really tied to anything diagnostic in the engine, as far as I know, it's just a reminder light, and you reset it on the back of the (speedo?tach?)


Personally, after futzing around with my mixture, timing, plugs, blah, blah, I've set the timing and mixture of my SC back to the book, and I'm happy. And, I don't breath gasoline fumes with my heater on, at a red light. And, I bought a new O2 sensor just for good measure, it was worth the $70 to me. I never could get it right with the "disconnect" and run a little richer kind of thing.

You can find the O2 sensor on the front side of the Catalytic converter (on the driver's side of the engine) towards the 'inside' of the Cat. Its 22 mm and has a thin black wire that goes into the engine bay. In the engine bay, if you remove the oblong black accordion-ish plastic tube for the heater blower, you can see the connector for the o2 sensor. That same black wire has a 2" long rubber sheath on it that is not unlike a spark plug boot. Be careful if you remove it, the male connector underneath is ceramic and is broken on proababy 2/3 of all the 911s out there. . . . . . You could probably stand to slice that rubber sheath about halfway to the top with a utility knife.

Thanks Gogar; honestly i don't even know if after 28 years that light and the reset in the back of the tach are still working...and since the car has 170K and i have no clue if it was ever replaced.....i prefer to simply change it, write id down when i changed it and amen :)

So if i understand correctly, the sensor is on the bottom left area; will try to jack up the car this weekend and look again :) can i access the cable from the engine compartment? or the accordion-ish plastic tube of the heater is the one on the bottom, where the heater exchanger are?

I am kinda confused, since someone said that i have to remove the rear left wheel to access to the sensor....from your description seems pretty much straight forward.

Thanks again! any idea of where to find a picture to see the position of the sensor? i've not bought the "bible" manual yet :D christmas is close thou!

Yes, Darshie. There's two steps involved, if you really think you want to replace your o2 sensor. Remove the left rear wheel, and you will see the exhaust. the parts look very similar, but not identical, to this. (this picture is from the rear of the car, let's say.)

http://forums.pelicanparts.com/uploa...1228204670.jpg

The catalytic converter is on the left side there, the big one that looks like a missile silo. There may be a flat "debris shield" on the bottom side of it. Here's another pic of the catalytic converter.

http://forums.pelicanparts.com/uploa...1228204762.gif

The o2 sensor is on the cat, towards the front, and has a black wire coming from it. It's a 22m hex, and it will probably be VERY DIFFICULT to remove, due to years of heat and rust, etc. Soak it with some PB blaster or Liquid Wrench or something and let it sit for a day or so before you try to remove it. There's even a special wrench you can buy right here on Pelican that will make it a little easier.

THEN, in the engine bay, you need to unplug the other end of that black wire. It's MUCH EASIER to find that end of the black wire if you look here:

http://forums.pelicanparts.com/uploa...1228204935.jpg

There's a black accordion-style heating tube in the mid-left portion of the engine bay. If you undo the clamps on either end of that tube and remove it, it's MUCH easier to see the other end of that black wire sneaking up from the exhaust, and to a fitting. Be very careful, and remove it. There's also a rubber grommet in the middle of that black wire that you will need to get out of the engine sheet metal.

Just search in the forums the words "o2 sensor connector " and "catalytic converter" and the like and there's literally thousands of pictures in here. Good luck!

o'riellys has a bosch one wire for 19.95

I've said this before, I have two dyno sheets posted here. One was my 80 with no 02 and mixture set to 3.4~3.5 second is .9 with o2 connected. The connected o2 made more power with superior AF ratios. If you have the US version 80 with the frequency valve you want to at least try and figure out.

I'm in the camp that says the '80-'83 SCs run very well on the stock lambda setup. The engine in my cab was essentially non-running when I bought it. As I rebuilt the engine, I also went through every fuel injection and vacuum component, cleaning, checking and spec'ing as much as I could. This included items like the 15- and 30-degree switch on the throttle body, etc. I had zip, zero, nada baseline performance to work from, so I set everything to what the reference books called for. Thinking back, I probably spent as much time cleaning and checking the CIS system as I did on other aspects of the engine rebuild.

I also cleaned and lubed the distributor (you could barely turn it -- think it had advance problems?) and did stuff like ohm-checking the plug wires. I had some sorting issues after starting the engine on the first crank (I ended up having a bad new oxygen sensor relay). Once that was resolved, I set the mixture using the test port connection and a dwell meter and I'm at a place where I could not be happier with how the engine runs.

I guess where I'm going with this is that the '80-'83 fuel injection/engine management systems are very right once everything is properly sorted.

Brian