Stuart

        An O2Snsr MostCertainlyDoes NeedToBeGrounded ~ Any Electrical"Circuit" 

HasToHave a CompleteLoop or Electrons Won'tFlow ~ You even say in your Test

explanation below 

"Clamp your negative voltmeter lead to the case, and the positive to the output wire."

On 31 Oct , 2014, at 11:56 AM, Stuart MacMillan wrote:

> The 02 sensor does not need to be grounded, but the ECU reading it does. The
> millivolt current is generated chemically between two internal electrodes,
> only one of which is connected to the ECU (the electrode the electrons have
> left for the other one, creating a + voltage), and the ECU measures that
> voltage to its internal ground. Note that the heater has two wires, ground
> and hot, it's the only part of the sensor that does need grounding, and it's
> not done through the exhaust for the reasons you mentioned. The heater wires
> are shielded to prevent inducing a current in the signal wire. 
> 
> I've installed single wire sensors on my MGBs for voltmeter carburetor
> tuning, and here is a good method for bench testing an 02 sensor that has
> saved me money over the years (from
> http://www.gnttype.org/techarea/ecmsensors/O2sensors.html):
> 
> "Testing O2 sensors on the workbench:
> 
> Use a high impedance DC voltmeter. Clamp the sensor in a vice, or use a
> plier or vice-grip to hold it. Clamp your negative voltmeter lead to the
> case, and the positive to the output wire. Use a propane torch set to high
> and the inner blue flame tip to heat the fluted or perforated area of the
> sensor. You should see a DC voltage of at least 0.6 within 20 seconds. If
> not, most likely cause is open circuit internally or lead fouling. If OK so
> far, remove from flame. You should see a drop to under 0.1 volt within 4
> seconds. If not it's likely silicone fouled. If still OK, heat for two full
> minutes and watch for drops in voltage. Sometimes, the internal connections
> will open up under heat. This is the same a loose wire and is a failure. If
> the sensor is OK at this point, and will switch from high to low quickly as
> you move the flame, the sensor is good. Bear in mind that good or bad is
> relative, with port fuel injection needing faster information than
> carbureted systems.
> 
> ANY O2 sensor that will generate 0.9 volts or more when heated, show 0.1
> volts or less within one second of flame removal, AND pass the two minute
> heat test is good regardless of age. When replacing a sensor, don't miss the
> opportunity to use the test above on the replacement. This will calibrate
> your evaluation skills and save you money in the future. There is almost
> always *no* benefit in replacing an oxygen sensor that will pass this test."
> 
> Stuart
> 
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
> OlRivrRat
> Sent: Friday, October 31, 2014 10:05 AM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Re: Single wire Oxygen sensor: Substitution report..
> 
>                Don
> 
>        How did you end up dealing with the Ground ~ It should, I believe,
> be taken
> 
> care of through the Body of the O2Snsr being in contact with the
> ExhaustSystem ~
> 
> But I choose not to trust that as the Joints&Bolts in that Path tend to get
> Crudded
> 
> over time, so I ScrewClamp a wire to the O2SnsrBody & attach the other end
> to a
> 
> Good BodyGroundPoint ~
> 
>                                                        ORR ~ DeanB
> 
> On 30 Oct , 2014, at 10:34 AM, Don Hanson wrote:
> 
>> I run digifant engine management for my inline VW ABA Jetta motored 
>> vanagon...same as the stock Vanagons but with the inline motor 
>> providing the go..A few weeks ago I had some problems with my engine
> management
>> system and traced it to a dysfunctional Oxygen sensor.    I'm almost
>> positive the problems were a result of bad wiring between the O2 
>> sensor and the ECU, but I have no actual confirmation of that.
>> 
>>  Anyhow, I was unhappy with the cost of replacing the Bosch 3-wire 
>> heated Oxygen sensor in my rig...the best I could find was about $70 
>> for another Bosch heated sensor, and  that one didn't even have the 
>> proper plug for my wiring harness...So I did some research, called 
>> around a bit and asked...and the general response was that I could 
>> replace that 3 wire heated oxygen sensor with the single wire Bosch 
>> sensor and save myself about $50 without any real downside to engine
> performance.  But......No one
>> would actually come right out and tell me that.   Lotta "Oh, that should
> be
>> OKs"...and "I don't see any reason why that wouldn't work 
>> fine"s....There was also some nebulous opinion as to how to properly 
>> connect the sensor...Should the shielded wire loom carry a grounding 
>> connection or not...etc...
>> 
>>  Anyhow I bought a single wire Bosch from Van Cafe and installed it.
>> The results are quite satisfactory.   The only downside has been that
> after
>> sustained highway driving if you shut off the motor for a short while 
>> the idle speed is a little low...low enough to stall sometimes...for 
>> just a couple of seconds, until the O2 sensor gathers enough heat to 
>> resume proper function, I guess.
>> 
>>  I have regained my fuel economy...back up to 24.xx mpg after 3000 
>> miles with the new sensor. the O2 sensor i again modulating the fuel 
>> mix properly....When running with the O2 sensor disconnected from the 
>> ECU, I was seeing around 4-6mpg less gas mileage but the motor felt 
>> quite happy and strong..
>> 
>>  So, in my case, I successfully saved some money on that part and gained
>> back my good gas mileage.   Here's a handy app to help you track your
>> fuel...there's one for the smart phones, too....
>> http://www.fuelly.com/dashboard
>