Has anyone changed from a 1 wire to 3 wire O2 Sensor?

[Vincent Hill]

I posted a thread about my Strange running 1982 - 911sc and no one replied. Sort of figuring that it is Fuel (because I have gone through all of the electrical related to Spark) I realized that it might be related to the O2 sensor that was Disconnected when I bought the car.

I am now picking up an O2 sensor Relay which a lot of people have spoken about causing some of the same issues I am having.

In my search I found some one with a 928 that had changed his Single wire O2 to a 3 wire so that there is a Heating element that will help Cold and warming up running.

Has anyone done this on their 911?

[psalt]

This would be of no use on an 82 SC. You want the car to warm up in open loop, heated O2 sensors are about meeting an OEM emission test sooner. A properly tuned 82 SC should start and run great, find out what the problem is and fix it. Have you read the duty cycle output from the test port ?

[Vincent Hill]

Originally Posted by psalt

This would be of no use on an 82 SC. You want the car to warm up in open loop, heated O2 sensors are about meeting an OEM emission test sooner. A properly tuned 82 SC should start and run great, find out what the problem is and fix it. Have you read the duty cycle output from the test port ?

"Test Port"? I have seen the threads talking about reading the resistance and what I should be looking for BUT Other than someone reading the O2 Sensor itself, NO>

I just started the car up without the relay and there was Absolutly no difference. One thing I did note is that the relay was wrapped in a Plastic Bag and sealed. so at least Water was not the problem (Maybe)

I thought putting in a Heated O2 sensor would cause the engine to run correctly sooner. Better fuel mileage would also result. I am getting about 24 on the Road and about 18 in town so I am not complaining! I get better mileage in the 1976 - 911s but I think that was because of not using Ethanol fuels when I had it.

[Vin-barrett]

Originally Posted by Vincent Hill

I just started the car up without the relay and there was Absolutly no difference.

just in case you havent, make sure your interior dome lamp works. The dome lamp fuse also protects the circuit for the frequency valve.
If you remove that relay there should be a very noticable change in how the car runs.
Sounds to me like your frequency valve isnt buzzing.

[Vincent Hill]

There is a Brave Man! Only my Grand Mother could get away with calling me "Vinnie"! A man named Pottiger used to call me Vinnie and one day in front of his friends I called him Potty and no more Vinnie!

Yes, My Dome Light do work. Thanks

I want to say Thank you to someone that did not post on this thread but knew the problem! John Walker I saw his post on another thread where he stated that the O2 Relay was a problem and I had already ordered one before I put up this thread.

I went to my friend at the Porsche Dealer and spent my $6.77 and the car runs almost perfect! Full Power everywhere. I only need to tighten up the A/F mixture to get the Idle right but it is working great!

Psalt, I still need to do more study on the 3 wire vs the 1 wire because I am still working on my exhaust. I bought a set of Short Tube SSI Heat Exchangers what were originally designed for a twin Turbo and will use "V-Band Clamps" to mount Off - Set 300 Hole Metallic Cats on the Secondaries that I can Switch out with straight Secondaries onto my 2 in and 2 out Muffler I got years ago from Australia. I do have to pass Emissions and want it perfect when I do go!

[psalt]

"Test Port"? I have seen the threads talking about reading the resistance and what I should be looking for BUT Other than someone reading the O2 Sensor itself, NO>


CIS lambda has a test port connector under the plastic cover on the left side of the engine compartment. If you hook up an analog dwell meter, it will tell you whether the system is functioning correctly and once it goes into closed loop, how the basic mixture is set. Much better than swappping parts in the dark. If you don't understand CIS lambda, my advice would be to read one of the Bosch publications, the blue book or Gasoline Engine Management to get an idea how the system works. Then search this site and you will find how to diagnose your problem. CIS lambda is different than CIS basic, the fuel pressures can be spot on and the engine still running like crap.

A heated O2 sensor would accomplish nothing. The warm up fuel mixture is controlled by the WUR altering the control pressure and your ECU is designed to delay closed loop until after that is over. If you are getting 24 mpg on the road, there is probably very little wrong with your system and if your pressures are correct, a few adjustments may be all you need.

What is the problem on one answered?

Paul

[Vin-barrett]

Originally Posted by Vincent Hill

There is a Brave Man! Only my Grand Mother could get away with calling me "Vinnie"! A man named Pottiger used to call me Vinnie and one day in front of his friends I called him Potty and no more Vinnie!

Ha!
I think here in New Jersey all Vincents are "Vinnys"

Glad your all sorted! must feel good

[Walt Fricke]

My favorite CIS book is Bosch Fuel Injection & Engine Management by Charles Probst. Probst is an SAE engineer type. When Psalt (another automotive engineer type) corrected me on how the frequency valve worked, I promptly found confirmation in Probst about differential pressures - something I had previously avoided really understanding. Well worth having in your library if you have CIS.

[Vincent Hill]

I "Actually" have the Bosch (or who ever makes it "YELLOW" CIS Book. I actually fairly well understand CIS [b]"Until" you throw in the O2 Sensor which my 1982 BMW 320I also has. I have several adapters that I made out of Injector Lines and control pressure lines to look at these things but the O2 I have not dealt with!

Now that I have had some initation (as my dad always said) "Experience is ALWAYS something you get IMMEDIATELY After you need it!" I am now More Experienced!

Did not know about that little relay until today but I was smart enough to figure out that the fuel problem was related to the O2 and looking "Here" today I found out about the relay.

Thank ALL of you including "Vincent"!