ok so i have my hedman headers installed and i relized that the O2 sits lower than it did on the mani, so...should i cut the wire the O2 hooks to and make it longer or do i need to go get a new one with a long wire?

 

Extend the wire on the vehicle side of the harness, not the o2. The o2 wire is a special resistance wire, and if you extend it, it could change the voltage readings at the ECM.

 

ok thanks, do u know what gauge (sp) wire i need?

 

Jegs sells GM 02 extenders.

 

Where did this "special wire" idea come from??? I'm not saying it's totally bogus, but I certainly question it.....

Besides, if you extend the wire say 12 inches, you're adding additional resistance regardless of where in the circuit you add it in! It's just normally considered (SOMEONE PLEASE CORRECT ME IF I'M WRONG!) that the increase is pretty minimal/negligible in the total scheme of things. So I'd say extending your wire a little bit to reach the new O2 bung should not be a problem. Just my opinion.

Now where I may differ with a few folks is this: You may want to consider going with a heated O2 sensor. Since your car is an 84, chances are you have a single wire o2 sensor. It may not heat up enough, especially at idle, to give correct readings. You may consider going with a 3 wire heated o2 sensor. The conversion is very easy (I did it so it has to be) and is covered elsewhere, just do a search. What it amounts to is 2 wires for power and ground and the third wire splices into your existing o2 wire. Works great with headers.

Hope this helps a bit without starting a flame war. Have a Great Day!!!


- Vern

 

It's not a problem extending it, as long as you extend it on the vehicle side of the harness. The vehicle side is standard copper wire. If you cut the resistance wire on the o2 side, it will render the sensor inaccurate and useless. Try doing a search on the subject, or picking up a book on it, it will all say the same thing. I suppose if you really wanted to, you could cut your wire off the o2 and measure the resistance with a DVOM. Heck, you could always splice it back up, right?

Question all you want, but right is right

EDIT: I just remembered I have a used bosch o2 laying around, so I decided to test it to prove this to myself as well. I had never seen this first hand either.

The 10" length of 16awg wire tested at .6 ohms. I also have a 22' length of 2awg wire laying behind me that I am going to use for my battery relocation. That length of massive wire tested at .1 ohms.

While you are right that a small length of wire would add a negligable amount of resistance, I think the problem will come in with either the heat from soldering, or a crimp connection that is almost certain to add resistance to the circuit.

 

Oh, and 16awg will work fine for the job.

 

Adding any amount of wire will add a little bit of resistance. However, the amount you add is insignificant for the type of system we run. In fact it is pretty much insignificant any way you look at it.

 

Read the edit above, I just tested it and posted the results. I didn't mean to sound cocky in the reply, that's what smilies are for

There has to be a reason they would add that much resistance to such a small wire gauge. For a length of wire that small and short, the resistance should be extremely low.

 

Yea I got you but soldering won't add any resistance to worry about.

 

I just extended mine on the o2 sensor side. (earlyier posts never claified that for me). Now im throwing an O2 sensor code for the first time, this may be why. Just letting you all know.

oh well, gives me a reason to buy a wide band O2 sensor.

 

Sorry, I still don't see where you add the wire makes any difference. If you add resistance "here" or "there", it doesn't matter, you've still added it. I suspect it's minimal, regardless.

Sorry for being so thick headed and stupid, but I don't see the difference... please enlighten me.

I suspect ssxmac's problem is he has a bad connection and the computer isn't seeing the O2 sensor at all, but I'd sure like to hear more to know/learn for sure.

Have a Great Day!


- Vern

 

You extened the wire on the 02 itself? If you did you detroyed the 02. You need to extend the wire from the harness and not the 02 itself.

 

That is exactly what I've been saying and both you and vern are saying that the effects would be minimal, if any!

And Vern, I didn't say anywhere that you were being thick headed or stupid. No hard feelings?

 

I guess we arguaing about the same thing Anyways you are right. I missunderstood you. I thought you were talking about extedning the wire harness on the car on not the wire attached to the 02 itself. Now we are on the same foot. Damaging the attached 02 wire is a no no.

 

So you're saying that if I installed a 3 wire sensor into my normally one wire 91 Firebird the following way:

1. I cut the wiring connector off the old sensor
2. Spliced the original sensor connector onto a new connector that mates with the new 3 wire sensor connector using a short piece of the old sensor wire (so that I could still use plug in a one-wire if I wanted/needed to)
3. Connected the other two wires to keyed power and ground

That I'm either getting bad o2 sensor readings or I might have fried the new 3 wire sensor?

I'm still at a loss on how this could happen.... but look forward to being educated.


- Vern

 

Sounds like you have killed both. I have never hooked up a 3 wire 02 but a quick search should tell you how to do it.

 

I just got this reply to the same question on another thread.
Enjoy

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