Thread: Regrounding the O2 Sensor

CORRECTED 07/28/08
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Your buggy has a strange O2 sensor.. But thats okay.. My old OEM sensor was just like yours. The screwy wires are as follows:
White = Signal wire (middle wire)
Black = Heater wire
Red = Heater wire
Note: The Bosch online pdf shows this differently for replacement O2 sensors!!
. . ** The Red & Black wires are interchangable since heater wires are not polarized.
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Welding a tab closeby the O2 bung is another good idea. But, when I was testing the surface of the SSAC, the surface did not carry ground very good. Thus, I then started using the joints as the connection points and got much better results.. Its just something about the SS surface that simply dont carry grounds...

Well ebay has some descent prices on those sensors, I wish I could find it for $30 like I did with my 3 wire one... not really wanting to pay $50...

Alright I just ordered one for $30 shipped! Got it from the same eBay member that I bought my other O2 sensor from.

If it comes in all good, I will ask the seller to post a proper auction and link it here

Big thanks to AztekSE-R for pointing me to the other thread thread in which DC Scotty has mentioned this whole ground deal.

You all just inspired me to go look at my O2 sensor.

I am running a turbo setup, but my J-Pipe has been replaced with a stainless steel pipe that dumps out of my front bumper. I am betting I am having similar problems with grounding.

Covert, let us know asap if the 4 wire works well.

Alright the Sensor has been shipped, it should be here by Wed next week.

Now I won't be able to fully test until I get a new Alternator...

I told the eBay seller if everything works out I will communicate his auctions to you guys and that he might get some sales from us

so just asking ....would it be a good or bad idea to just splice both white and red or just one of the two for ground?.....its late but figured i would ask before i knock out and wake up and cut stuff lol

REAL BAD IDEA! - Don't cut either of the heater wires! Your white & red wires are for the heater only... It has nothing to do with the
O2 Signal... Its a completely separate circuit and should remain intact in all instances.. The heater does not have polarity so, it doesnt matter which wires are connected to the heater wire BUT its for the HEATER only.. Leave the heater wires as-is in all cases! Trying to Ground the heater wires will cause the heater not to work and will have no impact on the O2 signal.

The O2 signal to the ECU is what we are trying to improve here. A 3-wire setup does not have a ground wire for the signal but uses the header as a ground. Additionally, if you have a Stainless Steel header, then this mod will probably help your O2 signal at idle as the grounding is being improved. Again, this mod is attempting to improve the Stainless grounding capability. So, if you have OEM steel/iron header, then your O2 signal is already strong and I doubt that this mod will improve your O2 signal.
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With that said, the O2 performance is still much better after a few days of driving the car; especially at idle and at lights. The bogging problem still exists and has not changed; so something unknown is still causing this problem.

V:
Thats great news on the 4 wire O2 sensor. This is looking like the best solution of all. Grounding the O2 sensor, regrounded MAF and ECU at the same grounding location has many good attributes. Just remember that you will need a 4-pin connector plugs to do this cleanly: Male O2 4pin plug to connect the New Universal 4-pin O2 sensor AND a Female O2 4pin plug to connect the NEW grounding wire from the connector back to the Intake Mani grounding location. Just connecting the gray O2 grounding wire to the block is easier and will also work, BUT not as well as the grounding effectiveness which much better at the intake mani and will match the ECU ground. (Just remember that during testing, the Header bolts & Valve Cover bolts were terrrible for grounding purposes; so they are NOT recommended grounding locations). Easier is not always better and testing is always required (otherwise you wont know if you improved anything or made it worse).

Good points, I will make the wire neat without having to get the 4-wire harness

Since I bought a universal one previously, I didn't cut the wires short, because I didn't like how tight the SSAC header made the wire.

So my temp solution was this



I later on fixed it with zipties


Now I don't really feel like running a wire all the way to the intake manifold, I was thinking this would bring the same effect. I already have some grounding done, it all meets up at the ECU ground...

(I'm thinking about attaching the O2 ground to here)


(The ground meets here)


(Once again my grounding map as of right now)

Vadim,
I know you are lazy. And I understand that you think the grounding location 3 is fine.

But testing grounding locations 3 and 8 on your map, I found that 3 was about 21% less than 8. Still good but not the best location. Your negative battery ground is just below location 3. Its much better with only a 9% lower difference to location 8. Optimum location will alway be location 8 and thats the best location with 0 differences. Remember to use the exact same gauge wire as the O2 sensor wire. Im going next size larger due to the 3foot wiring rule (every 3 feet of wire, you loose some wire resistance = increasing 1 size larger for every 3-4 foot in extra length).
Thus, if the original wire was 14 gauge and you needed to add 4 foot extension, the correct wire gauge for up to 6 more feet would be 12 gauge wire (lower gauge = larger wire).

Looking at your pictures, I noticed that you have a low-port engine with an operational EGR/EGR pipe and AIV is removed. How is your vacuum lines arranged for this setup? Did you also remove the AIV Control valve and plug the AIV vacuum line?

I know man, I've done too many things the long way on my car, so I guess I'm starting to want to cheat



Interesting! See I figured since the current wires connect to the intake mani anyways, that it wouldn't make a difference. Ok now then, which ECU ground should I use? Left or Right? Or doesn't make a difference? I will ground them together eventually too.

I'm using 8 gauge wire for my current grounds, the O2 sensor will get the 12 gauge treatment



EGR is working, but I want it gone hehe. Whats the AIV Control Valve? I can assure you I didn't remove it haha, I don't believe the previous owner was smart enough to do so either, considering the fact that they were not smart enough to change the oil . I'm the second owner btw...

It might be something of a 99 Sentra, 98 200sx thing. A lot of changes have happened in those models...