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3 wire O2 sensor application help

R

Russ

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I am trying to figure out the best way to hook up a 3 wire O2 sensor in the headers for a TBI 454 in my 88 dually. Currently there is only enough wire in the harness to reach the stock exhaust manifold location. If I put a sensor in the collector I will need at least another foot added to the factory wiring harness to reach. I have an AFS74 version O2 sensor, but it only has about a 12" pigtail on it.

Is there an O2 sensor that has a longer pigtail that will work for my application?
Is there a corresponding 3 wire plug that I can wire in to my harness for this sensor?
Is it a bad thing (as I have read) to solder an extension to my factory wiring harness for the sensor?
Thanks for the help,

Russ
 
I don't know why soldering axtra wire would be a bad thing. It might have something to do with the dissimilar metals from the wire to the solder making voltage and changing the O2 signal. I figure this would be so minimal it couldn't really effect the signal. We do it all the time in the Fleet I work in. I have converted lots of trucks from a one wire to a three wire O2 sensor. If this is what your doing you need to hook one white wire to fused ignition power and the other to ground and the black to the regular signal. You could hard wire it or pick up the pigtail from the dealer. I haven't done this on my truck because I don't really see much advantage to it on a gas motor. Normaly we do this conversion to natural gas powered vehicles to get them in to closed loop ASAP and keep them there. They run much better in closed loop. I hope this helps.
 
Thanks for the info. If I solder in extra wire to reach down to the headers, does it make a difference what type/size wire it is? I have not cut the sensor wire yet to see if it is just regular copper wire or what it is.

Russ
 
I did this on my 89 v3500... I used the factory plug and the corresponding gauge wire 16/18,,, I cant recall,, soldered everything and used heat shrink and then put it all in burn proof sleeve (because its close to exhaust) look factory,,, works factory,,, no problems

I do notice the truck smells less in warm up mode because it leans out quicker.... and I like that

cam
 
PeteH said:
someone needs to chime in....i want to know too
Click to expand...

What do you want to know?

16 guage regular copper wire will be fine. It's probably 18 but going bigger can't hurt.
 
O2 wires aren't just copper wire. I've watched the discussions on thirdgen about them, lots of theory, seems like there is no difference though when you mess with it.

Just as an FYI, the Camaro O2 wire has more than enough length to reach full length collectors, if you really wanted to be certain there was no change, you could get the wiring from one of them, (depinning the ECM connector and the weatherpack on the sensor side) grab the corresponding 3 prong weatherpack from another vehicle (like one that came stock with an AFS-74 type sensor) and pin it the way you want.

I'm doing it that way, but my O2 wire is already plenty long, and it wasn't much effort to find the other end of the 3 prong weatherpack.
 
it was fine stranded automotive wire,,, I havent tested the signal other than confirming there is one... I dont think resistance is a problem here.... but only an electrical engineer could tell you.. or a quick call to the bosch (thats what I used) tech line....
seat of the pants also tells me its working...

cam
 
I check them with a lab scope regularly and they are the same with or without a wire soldered in. The Comero sensor and pig tail sound like the way to go. Less work and will look beter.
 
russ,,, I forgot to add I had the truck on the dyno.... and the smog machine,, and one of the things read was the o2 sensor signal,,, and it was reading OK and the right volts,,,, and the fuel air ratio for the tbi was right where the factory specs wanted it to be,,, so the sensor did work as planned
 
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