Splice O2 sensor wire?

SlickDizzy said:

Glad I'm not crazy, I'm tired of people looking at me like I've just claimed the world is flat when I say they breathe through the wires...

Now explain to somebody that they need a new PCM and wiring harness to fix the O2 sensor code in their Dakota.  And a power steering pressure switch, which pumped the whole wiring harness and computer full of power steering fluid.

It's interesting to unplug an O2 sensor and find oil in it.  Then unplug the PCM and have oil pour out.

Sealed connectors seal in both directions.   When the power steering pressure switch fails, that high pressure fluid will get pumped through the wiring before it leaks out past the connector, and then when it gets to the PCM it will get distributed everywhere.  Oxygen sensors do not work when they are sampling oil...

sullivandavid73 said:

hi im building a vw trike . im putting efi on that has 1 o2 sensor. can i spice in a second o2 sensor. i have dual exhaust so single o2 sensor will not read cylinders 1 and 2. 

thank  david

No.  It will just have to read off of one bank.

Make sure the oxygen sensor is at least 18 inches or so away from the exhaust tip, as well, otherwise it will get falsed by outside air getting sucked back into the pipe.

"O2 sensors breathe through the wires ..."

It's clear that most folks have NOT A CLUE about how O2 sensors work, or electricity for that matter.

Humanity is DOOMED.

("I read it on the Internet, it MUST be true")

I'll confirm that the late 90s Mopar O2 sensors work just fine when you've cut and soldered the wires.  At least for the rear O2 on my Jeep... 

clshore said:

"O2 sensors breathe through the wires ..."

It's clear that most folks have NOT A CLUE about how O2 sensors work, or electricity for that matter.

Humanity is DOOMED.

 

("I read it on the Internet, it MUST be true")

I was told in training by the people who make the O2 sensors.  Your call.

The breathing through wires thing would be pretty strange, especially if it breathes past the connectors.  But oil getting forced through wires absolutely happens.  I've seen oily PCM connectors after an oil pressure sender failed and pushed oil into the wiring.  Once the connectors were cleaned, all was good.  Oil never made it into anywhere damaging, so it just corrosion protected the oil pressure sensor wires. 

In reply to rslifkin :

The breathing doesn't go past the first connector.  Doesn't need to- just needs a source of air. 

But the sensor requires a good source of air for it to be accurate- that's just how they work.  It compares air vs. the amount of oxidants left in the exhaust stream.  The less, the higher the voltage.  

Sounds strange, no question.  It is how they work.  But it's more important for WB sensors, and they actually pump air into the sensor.  No idea how, but I know they do. 

Again, previously, the sensors had a tiny hole in the housing.

alfadriver said:Sounds strange, no question.  It is how they work.  But it's more important for WB sensors, and they actually pump air into the sensor.  No idea how, but I know they do.

I don't think they pump air into the sensor so much as they pump current (electrons) into or out of a simulated outside-air reference to try to make the cell read .450v,, and the current amount and direction will tell you what the approximate lambda is.

But yeah, now that I think about it, there still would have to be an outside reference even though the cell contacting the exhaust is only getting a "fake" reference.  Okay, time to find my books...

I knew I wasn't crazy when I tried to explain this to a co worker.

1988RedT2 said:

In reply to spitfirebill:

I have trouble with that one also. Every crimped connection I've ever seen has been weak and prone to failure. Every soldered connection I've ever seen has been secure and unbreakable. And still they say that in an automotive environment the crimp is superior. I've heard it a thousand times, yet deep down, I don't believe it. Not for a second.

There's a big difference between a crimped connection made using a tool and die set designed specifically for that specific pin, and one made using the $20 HF tool.  

A good crimp will make a good connection.  As will a properly done soldered connection unless it's in an environment prone to cracking the solder (which I've never had an issue with in a car).  But a crappy crimp will be crappy.  Use good connectors and a good crimping tool and you won't get crappy crimps.  

I did not come here expecting to learn how O2 sensors work. Nor did I ever think about. But, I have to admit, I'm glad I do now. 

thatsnowinnebago said:

I did not come here expecting to learn how O2 sensors work. Nor did I ever think about. But, I have to admit, I'm glad I do now. 

I'm sure we can explain more, if you want.  Especially how the sensor acts as a battery, and the voltage of that battery is the relationship between O2 and whatever oxidants are left in the exhaust.  

It's one of the most important discoveries for the car, and happened in the mid to late '70s.   Then how it's natural sensor reading just *happened* to be exactly what catalysts want to see.  Pretty amazing (at least to nerds like me).

In reply to alfadriver :

The amazing thing to me is that they work at all!

There are so many things that could incrementally affect oxygen content in the exhausts due to incomplete combustion!  How are they even remotely as accurate as they are?

But they're pretty dang good, and fairly accurate short of encountering a dead miss.

thatsnowinnebago said:

I did not come here expecting to learn how O2 sensors work. Nor did I ever think about. But, I have to admit, I'm glad I do now. 

+1 I feel like this is just the tip of the iceberg 

Yes, a surprisingly informative thread. Learned something new today.

Knurled. said:

In reply to alfadriver :

The amazing thing to me is that they work at all!

 

There are so many things that could incrementally affect oxygen content in the exhausts due to incomplete combustion!  How are they even remotely as accurate as they are?

 

But they're pretty dang good, and fairly accurate short of encountering a dead miss.

That's a really good question- and the answer is that the thimble is first a catalyst, and second a battery (the reaction really causes the voltage- just like a normal battery).  So it makes sure that the gasses are completely combusted WRT the oxidant/reductant ratio.  NOx and O2 act the same, so as long as the HC and CO are as reduced as possible, the battery works correctly.  It's pretty cool.  Not to say that certain things can really throw it off- H2 is so easy to convert, it's reaction will shift the signal abnormally rich- but you only see that on the cat monitor O2 sensor.

In reply to alfadriver :

That explains why O2 sensors work on rotaries, which are really good for burning "most" of the fuel and air, on a good day, when it's under load and the spark plugs are fresh.  The rest of the time.... ehh, that is what thermal reactors are for.  Or two precats in series before a main converter the size of a truck's, in 1981.

I'm glad I saw this as well. I'm planning to install a 3-wire heated O2 sensor on my car to replace the single wire non-heated stock one and was SO going to solder them and may have been tempted to make the connections close to the sensor.

In reply to GCrites80s :

How are you planning on running the heater?  The reason I ask is that it's not a good idea to just run it off of key power- if you can find a signal that is delayed some, so that you are not turning the heater on when there's a possibility of water drops, you won't crack the heater.  

And FWIW, if you ground the non-signal line on a 4 wire O2 sensor, you can use one of those, too.  

In reply to clshore :

Maybe you're forgetting what alfadriver does for a living, but internet or not, when he posts anything related to automotive emissions, I tend to believe him.

alfadriver said:

In reply to GCrites80s :

How are you planning on running the heater?  The reason I ask is that it's not a good idea to just run it off of key power- if you can find a signal that is delayed some, so that you are not turning the heater on when there's a possibility of water drops, you won't crack the heater.  

And FWIW, if you ground the non-signal line on a 4 wire O2 sensor, you can use one of those, too.  

Hmm, I'll have to think about one with a delay that isn't too long. On the 3rd Gen F-bodies, the one of the main reasons why you want the heated O2 sensor is to get it into closed-loop operation faster since modified cars like mine run a lot worse in open loop than closed. I can't think of a wire that would have a delay that's short enough. Most things like the fans will make you wait until 180 degrees or higher (a lot of F-body people are on Team Cold and set everything to come on at 160 but I don't). If I place the sensor properly I shouldn't have to worry about water though on this car at least.

GCrites80s said:

alfadriver said:

In reply to GCrites80s :

How are you planning on running the heater?  The reason I ask is that it's not a good idea to just run it off of key power- if you can find a signal that is delayed some, so that you are not turning the heater on when there's a possibility of water drops, you won't crack the heater.  

And FWIW, if you ground the non-signal line on a 4 wire O2 sensor, you can use one of those, too.  

Hmm, I'll have to think about one with a delay that isn't too long. On the 3rd Gen F-bodies, the one of the main reasons why you want the heated O2 sensor is to get it into closed-loop operation faster since modified cars like mine run a lot worse in open loop than closed. I can't think of a wire that would have a delay that's short enough. Most things like the fans will make you wait until 180 degrees or higher (a lot of F-body people are on Team Cold and set everything to come on at 160 but I don't). If I place the sensor properly I shouldn't have to worry about water though on this car at least.

If you can wait 10 seconds before turning on the heater, that would be good enough.  So a simple one time delay box would work.

In reply to GCrites80s :

Why not the fuel pump circuit?

Knurled. said:

In reply to GCrites80s :

Why not the fuel pump circuit?

That turns on with the key, right?  I'm pointing out that you need to avoid that, so that the risk of breaking the O2 heater from water drops hitting it is mitigated.  Even a 5 second delay should make sure the area around the sensor is well above the dew point in the exhaust.