Sorry for not explaining what was posted. As can be seen from the diagrams, Lambda (1.0) is the focal point, and represents the optimal fuel mixture point for emissions and fuel economy.
The O2 sensor when connected attempts to achieve a Lambda of 1.0.

By using the graphs, one can easily determine what happens when Lambda is greater or less than 1.0 to all the key variables of an internal combustion engine (ICE).
These variables are fuel consumption, torque, carbon monoxide, and hydrocarbons. As one can see from the graphs, it's best to have a good working O2 sensor system.

Now it makes sense. Thanks Dave.

If an Ox sensor is serving to optimize the fuel mixture, why run an engine without it?
.

https://i.pinimg.com/originals/c1/a0...36aba5e792.gif

Because some people dont adequately utilize their brain...

So according to you all owners with 911 ,racing or not, without catalyst and oxy sensor have problem with their brains,dude kinda insulting don`t you think?;-)))

Ivan

No sir. I stated some.

You interpreted all.

Never mentioned a "problem with their brains."

I stated they don't adequately use them, like for critical analysis.

The context wasn't "without catalyst and oxy sensor..."

It was with cat, and running without an O2 sensor resulting in a computer trying to calculate optimum running conditions, but unable to do so.

Just some subtle, but significant differences 🙂

well,i suppose you answered to Karl question
"If an Ox sensor is serving to optimize the fuel mixture, why run an engine without it?


well..i `m guilty that i did not adequately use my brain past 40 years;-)))That is just fine with me......

Ivan

Question about running engine with or without Ox sensor is not to offend anyone or create conflict. Am simply attempting to makes sense of how best to skin the cat I have. Clearly my engine is running better without the Ox connected than with it---notably this "running better" being without the Ox sensor I supposedly screwed up by soldering in the splices.

There's now a new twist to the puzzle...

http://forums.pelicanparts.com/uploa...1715206980.JPG

http://forums.pelicanparts.com/uploa...1715206980.JPG

Looked at new Bosch Ox sensor I just received. This is same part number (13918) I’ve been running for years.


http://forums.pelicanparts.com/uploa...1715206980.JPG

Then looked at Ox in car for a comparison. Electrical prong that should be on car’s side… is inside Ox sensor connector—wire has snapped at prong. Exactly when this occurred is unknown. This adds a curious twist to the situation. Now have to consider if this has anything to do with the fuel issue or is this just a good find and otherwise inconsequential to what's really wrong?


http://forums.pelicanparts.com/uploa...1715206980.JPG

http://forums.pelicanparts.com/uploa...1715206980.JPG

To answer that, prong returns to where it belongs. Then reconnected this Ox sensor—this has the solder-spliced wires that Bosch says “don’t do that.” Started engine and after it lowered to 800 rpm… not a horrible idle but not a smooth one either. Gen light is ON. Engine's struggling. Rev’d throttle slightly and engine sputtered. Shut down and disconnected the Ox. Restart… drop to 800 and smooth as silk. Rev’d same as before and no issue. As pieces of this puzzle come together, the soldered splice seems increasingly to blame.

City mileage test without Ox continues.

Seems to me you already proved it runs better without an O2 sensor than with the soldered one connected.

It's not clear which connector got broken, the one on the car or the one on the new sensor?

Will these cars run without an 02 sensor? Yes, although probably a little rich.

Will they run better with a working sensor, also yes. When these cars were produced this was proven, state of the art technology.

In all the discussion on this thread I haven't heard a good reason not to use it.

It's impossible to claim that the car "runs better" without the O2 sensor when it's connection is so compromised that it is doubtful that a quality signal is actually reaching the dme. It is logical to claim that this engine does run better without a likely faulty O2 circuit, and a doubtfully correct emissions setting given the changes to components made without excluding other variables.

Both Kroon and Sierra Madre Collection offer the harness side connector that can replace the broken connector.

1. The 911 3.2 uses a heated O2 sensor, that's two additional connections (white wires - 12V engine running) at the sensor.
Without the heater, the sensor might not function properly at low RPM.
2. To determine whether the O2 will function properly;
a. Use a voltmeter to test the O2 wire from the DME ECM (pin 24). It should be about .50V NOT connected.
b. With the engine warm, measure the O2 sensor (not connected). It should be at a voltage between .20 & .80 at idle.
3. To check that the DME ECM's O2 circuitry is functioning properly;
a. ground pin 24 - should take with in a minute to start to make black smoke
b. use a AA battery and connect the plus pin to pin 24 and ground the negative pin of the battery,
the engine should start to idle very low (200 - 300 RPM).

Brian... engine does "run better" without the Ox sensor given the condition mine was and now is in---somewhere along the way the single wire broke at the prong. That is the male side of the connection that belongs on the car side of the connection. There's a bracket mounted to the car's frame that holds that prong along with the 2-wire connection positioned just above the prong.

Though the 1-wire (signal I assume) broke away from the prong, it's possible it still made a connection. Maybe sometimes, all the time, or not at all. And so my reconnecting that break and testing how the engine ran with that fix. Not well is the answer and so the finger now pointing more clearly to my soldering the splices being the problem here.


That's the way I see it 917. You are phrasing things with great clarity. (My wording was not as precise as it could have been.)

Thanks for the note on Kroon and SM. I'll look into that. For the time being, I've soldered the prong back onto the single wire and run that wire / prong through some tubing. Threads on the prong turned tightly into the tubing used so the prong is securely positioned (not to be pushed in by the female connector.)


Appreciate the diagnostic notes Dave. Impressive knowledge on your part but I don't know this stuff like you do so need a bit more info to make sense of it.
.

Related info:

"You can just use a digital voltmeter (dc setting) and read the voltage off the O2 sensor. 0.2 volts and below is too lean, and 0.8 and above is too rich. When you get it to fluctuate in between at idle, you will have it just right, for it is a fine line just to get it in there. Make sure you have the car at full running temp before finalizing the adjustment."

--- Steve Wong here on PPF




http://forums.pelicanparts.com/uploa...1715277518.jpg

http://forums.pelicanparts.com/uploa...1715277518.jpg

--- Harold here on PPF



Harold used some gadget from DataQ to get the data on his laptop. Have PM'd asking him what that gadget is.
.

It does appear that Sierra is selling Kroon's product, which is useful since you don't have to wait for importing it.

Here's how to splice the new to the existing - turn down the volume because the music sucks!

https://youtu.be/GL8cJ6CJY8o?si=zNwAxW2HuoKdAN7g

http://forums.pelicanparts.com/uploa...1716632221.jpg

My solder-extended version that has been installed, and new stock unit that is same Bosch part (13918) without my altering it.

Scope tested both of these. Correct AFR for 3.2 per Steve Wong is when signal ranges (fluctuates) between 0.2 and 0.8 v with engine at operating temp and at idle. (Less than 0.2 is lean. Greater than 0.8 is rich.)

Scope settings:

Volts - each vertical square = 0.1v.
Time - each horizontally square = 0.1 ms.

0 volt level is indicated by the small arrow at the far left on the data screen.

Scope is connected to sensor’s black wire. Ox sensor is NOT connected to the ECU/DME so the AFR here is without input from the Ox. A few days ago, the Air Flow Disk was turned back to its original position, and ECU/DME fuel adjustment switch turned back to 0.

Engine’s idling at 800 rpm and is at 210 dF.


<iframe width="560" height="315" src="https://www.youtube.com/embed/OJqAJXkr1ug?si=0EHXjcEBFhTkblgy" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen></iframe>

Ox with soldered wires spliced in.


<iframe width="560" height="315" src="https://www.youtube.com/embed/tTTFZNX3qrk?si=jn7u_TwXvjYx8RvO" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen></iframe>

Same Bosch sensor without being modified.


Have not driven with the new Ox sensor connected to the ECU/DME. City mileage test without Ox connected remains in progress and don’t want to “contaminate” results. When city mpg test is completed, will connect new Ox sensor (to ECU/DME) and repeat the Islamorada highway drive, then the city mpg tests. Will also scope test the newly installed Ox sensor at speed.

.

This was posted in post #70! The one referenced must have read post #70.

Dave... You did say the same as Steve. I honestly got lost with the connect to "pin 24" thing. Don't intend to be rude but I was. Pardon me.

See, he too reads and learns from the Forum.

For the record, please correct my quoted values, not .02 and .08 volts, the correct range is between 0.2 and 0.8.

Reference the original post from 2001 that I was quoted from:

http://forums.pelicanparts.com/porsche-911-technical-forum/54799-mixture-adjustment-84-3-2-a.html

Or you can just use a digital voltmeter (dc setting) and read the voltage off the O2 sensor. 0.2 volts and below is too lean, and 0.8 and above is too rich. When you get it to fluctuate in between at idle, you will have it just right, for it is a fine line just to get it in there. Make sure you have the car at full running temp before finalizing the adjustment.


And yes, I see that Loren, or ahem, I mean "Dave" has also been properly searching for, reading, and learning from my posts in this forum, as he quoted my values correctly!!!

And yes, I see that Loren, or ahem, I mean "Dave" has also been properly searching for, reading, and learning from my posts in this forum, as he quoted my values correctly!!![/QUOTE]

:D:D

http://forums.pelicanparts.com/support/smileys/wat6.gif

Thank you Steve. Corrected.
.