Is the O2 sensor needed on a 80 3.0L ?

[RickKlem]

I am installing a 80 3.0L into my 77 911 , I also am adding SSI Heat exchangers . The SSI's have a hole for the O2 sensor, do I need to use the O2 sensor or can I just plug the hole and if so what size is the hole ( what do I need to plug it with?) If I do not have to use the sensor do I need to do any thing to the engine or car ?


Thanks
Rick

1977 911 3.0L

[ChrisBennet]

The plug is 18x1.5 I believe. I found a drain plug that size at my metric hardware source.
-Chris

[ruf-porsche]

I think that most 02 sensors has the same type of threads as most spark plugs. That what we use to chase out the cat converter threads on my brother's Audi V8 Quattro when we had to replace the 02 sensor. If you don't have the brain for the 02 sensor (located under the passenger side seat of cars with 02 sensor), I guess you won't be able to hook it up.

Earlier SC's used an air pump instead of the 02 sensor to control emission.

[1980SC]

You don't need to have the O2 sensor. I wouldn't bother with it. But you do need to have the brain and frequency valve if you are using the lambda style fuel distributor. The engine will run lean without them.

Rob
1980SC

[RickKlem]

Rob

When you say

" But you do need to have the brain and frequency valve if you are using the lambda style fuel distributor. The engine will run lean without them. "

Are you saying that this engine (80 3.0L) has a DME (brain) or are you talking about the cd unit ? Also where is the "frequency Valve" located. I'm not sure if I have the " lambda style fuel distrbutor or not. How can I tell? I'm new to the 3.0L my old engine was a 77 2.7 and it didnt have this stuff on it.

Thanks
Rick

[ruf-porsche]

If the engine is out of a 1980 or later 911SC than it has the lambda setup. It the engine is from a 78 or 79 91SC than it doesn't have the lambda setup. DME is in the motronic engine which were 1984 and later Carrera

[sammyg2]

I know of several 911SC owners who disconnected their O2 sensor and run with out it. The fuel distributor can be adjusted for the desired mixture ratio.
My car ran for quite a while without an O2 sensor when I first got the car. It even passed smog test with it disconnected.

[1980SC]

If you have a 930/09 motor, it is a 1980 euro and is non-lambda. It will be an easy install and does not need any O2 sensor stuff.

If you have a 930/07 motor, it is a 1980 USA engine, and is lambda controlled. You must have the computer for it which resides under the passenger seat. It is needed to control the frequency valve which bleeds off excess fuel pressure in the lower chamber of the fuel distributor. Without the computer, the pressure in the lower chamber will be too high, and your engine will run lean. My engine was worn out prematurely from being run without the frequency valve and computer.

Here is the non-lambda fuel distributor on the left, and lambda style on the right :



If you have the USA motor and the computer, you can leave off the O2 sensor. It will run fine.

Rob
1980SC

[1980SC]

Here is a picture of the back of the USA motor. The frequency valve is in the center of the photo, and is plumbed into one of the fuel lines coming out of the back of the lambda style fuel distributor.



The computer is needed to control this valve.

Rob
1980SC