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1966-2013
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Discussion Starter #1 (Edited)
You guys recall the story about the member who's mechanic told him never to solder an O2 wire because it would mess something up? (I think it was in that thread that had the numbers for a lot of inexpensive heated replacement sensors)

I was poking around the net a bit and stumbled across this bit of *cough* wisdom *cough~hack* in regard to just that subject:

Do Not Solder Wires!
Use wire crimps or Posi-LockÒ. All the latest BOSCH O2 sensors are air tight. But the O2 sensor must have a clean air supply to work. It breaths down the center of the multi-stranded wire(s). Solder and solder flux will close the air-gaps between the strands of wire and the O2 sensor may malfunction.



So there you have it, soldering stops the sensor from 'breathing' through the wire properly....

whatta maroon. :roflmfao:
 

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Tifosi,

Many thanks for this critical, high-tech information. In addition, there may be a lead to another important characteristic; is it possible that closing the air spaces between wire strands could restrict the escape of "smoke" in case of an electrical malfunction?. Should we go out and put a little spot of solder on the ends of all of the wires in the wiring harness - just in case?

(Are you taking anything for that cough?)

You guys recall the story about the member who's mechanic told him never to solder an O2 wire because it would mess something up? (I think it was in that thread that had the numbers for a lot of inexpensive heated replacement sensors)

I was poking around the net a bit and stumbled across this bit of *cough* wisdom *cough~hack* in regard to just that subject:

Do Not Solder Wires!
Use wire crimps or Posi-LockÒ. All the latest BOSCH O2 sensors are air tight. But the O2 sensor must have a clean air supply to work. It breaths down the center of the multi-stranded wire(s). Solder and solder flux will close the air-gaps between the strands of wire and the O2 sensor may malfunction.



So there you have it, soldering stops the sensor from 'breathing' through the wire properly....

whatta maroon. :roflmfao:
 

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1966-2013
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Discussion Starter #3
That seems viable. After all, most soldered connections lose thier smoke only through holes in the insulation, not the ends :)

Nope, nothing for the cough. Just more cigarette tar to try and keep it pinned down in my lungs.
 

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OK I remember reading that post too. I still don't believe you should never solder the O2 wires, but....

Had to get the dreaded smog test in January. I was in the process of changing my exhaust system. About a week before going to smog, my one piece manifold was changed to a two piece with the matching downpipes, brand new CAT, brand new 3 wire Bosch O2 sensor, and new wire from the bottom of the car up to connectors up by the fire wall. Wire connections under the car were nice, clean, both mechanically and electronically strong "western union" style. They were soldered and heat shrink covered. Go to Smog, would not pass. Try to adjust, no pass. All indications and testing with Ohm meter, following L-Jet guide showed O2 sensor as working properly....

Well, it was not actually behaving properly for some reason and was keeping the mix too rich for passing the smog test. Cut the solder connections out, crimped them together and passed.

Later talking to my ALFA and a Porsche mechanic their words of wisdom were also to never solder the connections. Porsche guy saying this comes straight from Bosch etc. etc. Why, they don't know for sure either. The only thing they could surmise was that perhaps the impedance could be tweaked enough in some way to affect the readings and behavior of the O2 sensor to the computer. So... if you have a new O2 sensor, solder the connections and don't pass, you can try crimping them instead and you might pass.

I know it doesn't make sense at all. Goes along the lines of the sensor breathing through the wires.
 

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1966-2013
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Discussion Starter #5 (Edited)
I'd think in your case it really was a change in impendance, but because of the pigtail splice, not the solder.

Once all tied up, that's a lotta wire in a more or less of a wad that can make for a resistance 'hot spot'. A western union pigtail splice is more for connections you don't want to pull apart through linear stress, something that's not really a thing in that circut, or harness in general.

A blasting machine can punch juice through a few of those splices, but at less than a volt output, an O2 sensor isn't going to be nearly as powerful. (imagine how a set of stereo speakers sound with umpteen splices in the wires. Same relative effect: degradation of signal)

Conversely, a good crimp would 'choke' the wires too making for a 'suffocation' effect anyway. ;) (Bosch prolly suggested crimp only onnaconna they don't want the liability of people who can't solder for s*** and put 9lbs of solder on yet still don't get a good connection, or who burn out a brand new sensor by not paying attention to where heat from the iron is going. Crimping is the 'safe bet' that almost anyone can accomplish with some degree of consitancy or quality of connection)
 

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Ya know, for some reason I was really worried about the connection pulling apart there and that was the exact reason why I used that type of connection LOL. Go figure. I would have been fine with a simple crimp and spot of solder, but no I have to go and over think the situation.

I was also thinking the three connections of twisted wire may have tweaked the impedance enough to change how the sensor behaved.

BTW, I try to keep my solder connections under 9 lbs. and try to only use 1/2 a spool of solder per connection:eek:.
 

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1966-2013
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Discussion Starter #8 (Edited)
I've always done it like the attached with good results (more or less the start of a western union, but much more compact and no redundant loop)

I don't tin the wires first either, which may be partially responsible for the success rate. Less impendance and direct wire to wire contact with no solder to fight through but instead lets the solder act more as a jacket. I use a high silver content flux core solder also if that has any bearing.

I also like to burn the ends of the wires with a lighter regardless of method used to strip the insulation as the flame will cook off any residual lubricant or deliberate coating applied at the factory to preserve the wire or help the pulling process. (coatings creates impendance)
 

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The splices I usually make are similar. I don't usually tin the connection first either, but in the same manner as you describe. They usually wind up being about 5/8 to 3/4 of an inch long. I probably had about 6 or 7 turns on each side though. I'm thinking that the amount of wire and twists was enough to tweak the impedance and cause my problem, more so than the solder.
 

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Last time I soldered a wire like on the O2 device, I was able to successfully solder all the way around and not interfere with the hole in the middle. :p:rolleyes:
 
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