can you splise the wires using solder and heat shrinking

 

No, the sensors get their reference air through the insulation of the wires, if you solder or disturb the wiring in a way that the sensor can't get its reference air through the wire insulation the sensor dies.

 

Really? I cut my wires in the middle and put extensions in when I did the longtubes last year, they still seem to be running fine? Nock on wood. I have never heard of this before, and I have messed with O2's for years without problems?

 

Tom, that's wild - please send me a link on that - I' need to understand that a lot better...thanks

 

Yes you can, it's just wire. And no it's not magical wire. Solder the wires and shrink the heatshrink and your done.

Douglas in Green Bay

 

a little late for April fool's.

 

I tried soldering one on a jeep the solder would not stick the the wire, use wire connectors and make sure they are closed tight and will not pull apart, I squeezed mine shut with some vice grips.

 

No joke

It is actually in the GM manual somewhere. I can tell you guess from personal experience that I had fouled the sensor by flooding the open connector with coolant. This was in my old 95 C4 with the LT1 engine. Even after cleaning the connector out with contact cleaner and compressed air, after 5 miles the sensor (suffocated) and indicated an erroneous lean condition causing the PCM to go full rich on one bank. Upon further investigation with a tech1 the bank 2 sensor was pegged at near .002 volts and the fuel trims for bank two was pegged. After reading the service manual I found that the sensors needed to reference their reading to outside air, and the only way they do this is by "breathing" through the insulation of the wiring. They don't require much air but neverless do require it as little as it maybe.

This reference air requirement is for all zirconia based sensors, if the current sensors are made with some other element this may not hold true any more, however I do beleive that are sensors are still made with Zirconia. Having said that I am very careful with the sensors when I have their connectors open taking care to keep outside elements away from them.

There is some reference information available here:

http://wbo2.com/lsu/oxygen13-17.pdf

Here is another article from the ISA which the Instrument Society of America that I belong to as member:

http://www.isa.org/InTechTemplate.cf...ontentID=44382

It isn't an automotive sensor but it is a zirconica based sensor that is used for stack emissions in a industrial enviroment but the operating principals are the same.

Also I know its in the older 92 and up GM Corvette manuals.

The other issue with splicing wires on these sensors is that you now have a splice that if not made correctly can cause issues with the sensor signal. Remember the signal that the PCM receives is from 0 to 1.00 volts, any resistance in poor solder or crimp joint will cause resistance and a voltage drop, at these voltage levels a drop of even a couple tenths can have drastic changes to how the PCM interpets whats going on in the exhaust stream. I have personally repinned the connectors using the correct terminals and crimp tools and have not had any problems. I have seen other customers coming in with sensors that were fouled after the engine was apart and their connectors fouled with grease, oil and or anti-freeze.

 

Don't take this as an insult, but sorry,there is no way the O2 sensor relies on wire insulation itself breathing. If that were true, the there would be all kinds of unpredictable and uncontrollable results in the reference signal because its under the car subject to water, oil, and dirt.

The first article states the following detailing the construction of the O2 sensor:
The inner cavity is open to the atmosphere which serves as the unit’s reference gas.

I worked at an electronics company and splicing wires on sensitive sensors is a big no-no because it can add impedance, resistance, and other undesirable affects. Even messing with connectors themselves can be tricky. Crimping then silver soldering is better followed by shrink wrap with a sealant to protect the splice from exposure to the elements. Different gauges of wire and the diameters of the individual strands also changes things a little.

 

As the previous post indicates splicing a wire may not be as easy to do as people think since they can't control the resistance of their splice. With electronic reference signals very small variations in resistance or impedance can degrade the signal. Also it seems there is some sort of path through the wire for a clean air reference.

Here is the info from the Service Manual:

Service Information

2008 Chevrolet Corvette | Corvette (VIN Y) Service Manual | Power and Signal Distribution | Wiring Systems and Power Management | Diagnostic Information and Procedures | Document ID: 303655

Heated Oxygen Sensor Wiring Repairs
Tools Required

J-38125 Terminal Repair Kit
Notice: Do not solder repairs under any circumstances as this could result in the air reference being obstructed.
If the heated oxygen sensor pigtail wiring, connector, or terminal is damaged the entire oxygen sensor assembly must be replaced. Do not attempt to repair the wiring, connector, or terminals. In order for the sensor to function properly it must have a clean air reference. This clean air reference is obtained by way of the oxygen sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degrade oxygen sensor performance.
The following guidelines should be used when servicing the heated oxygen sensor:
•
Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor, causing poor performance. Also, the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems.


•
Neither the sensor nor vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire.


•
Do not remove or defeat the oxygen sensor ground wire (where applicable). Vehicles that utilize the ground wire sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance.


•
To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector.


Bill

 

Thanks Bill, I knew it was in the manual somewhere. The stack emissions o2 monitoring instruments also required the same reference air for the sensor to work properly, however in that situation reference air to the sensor was introduced in a different manner. In the automotive industry it is a standard for the manufacturers to build the sensors in the this manner as it has been since the o2 sensor has been in use since the late 70s. In this respect nothing has changed in the design of the sensor as long as its a zirconia based element. Also I as I have mentione earlier I had personal experience with such failures coming into my shop and in my personal car after contaminating the connector with coolant. On several instances it was due to customers elongating the wiring by either splicing or soldering connectors to extend the harness due to headers or other mods.

 

Part of the problem may be poor terminology in the manual. Most are reading it to mean that we can't cut/ splice/solder the wiring due to either a resistance change or "air reference signal". I think the manual is referring to the connections to the sensor itself, not to the wiring downstream of the sensor.

If this was so then adding plug in extensions as everybody that adds headers does would also change the resistance or air signal. All of us that installed headers know that adding extensions DOES NOT destroy the signal or air reference to either the front or rear O2 sensors. A properly spliced wire doesn't add any more resistence than a plug in extension. I see no reason that we couldn't splice in a foot or two of the proper wire guage without any problem. The electronics don't know the difference between a splice and a plug in extension.

Remember that this is the same manual that says we have to change the thermostat housing to change thermostats and the same manual that says we have to drain coolant to change intake manifolds.

 

When I changed my headers and cats on my C6, there was unuf surplus wire wrapped in the wiring harness. Simply let it out.

 

You are correct, the manual keeps those that simply, "don't know" from making a mistake. A mistake can be made a thousand ways, but to do it right takes someone who is trained.

The manual is meant for mechanics who understand.

With that said, cut the wire as far from the sensor as possible to avoid damaging the Oxygen sensor and solder and heat shrink.

Douglas in Green Bay

 

But the Manual "mistakes" make me wonder just how much any part can be trusted. If they cut and paste procedures on intake manifold R&R and thermostat R&R from the early 90's into the C6 Manual what other procedures are ignorant cut and paste? Torque values? Logic trees on electronics?

Helms editing and/or quality control is terrible but they have a lock on publishing the books. We don't have any alternative but our own experience.

 

My comments on the Helms manuals was based on my experience with the 2 volume '05. I just received the '08 3 volume version and they fixed the t'stat R&R and the intake manifold R&R. still a problem with Brakes, they still don't seem to realise that there is an 18mm nut on the caliper pin.