WBO2 vs. stock O2 confusion

[Calan]

Ill be installing a Zeitronix WB in a day or so and, I think my stock O2 is on it's way out. (doesn't cycle at idle, etc.). Should I use the simulated/narrowband output of the Zeitronix to the ECU and just plug the stock bung? Doesn't make much sense to have to also replace the stock sensor. One advantage of the Z's narrowband output is that it is programmable.

Maybe I'm just confused, but...

If I'm tuning with the WB, but the ECU is still reading a "stock" narrowband signal, how does the tuning work out? If the narrowband isn't reading exactly the same and isn't as accurate as the WB, isn't the ECU gonna try to make corrections based on that, rather than taking advantage of the A/F changes that I make via the WB?

This is why I'm guessing that the simulated output to the ECU is the way to go, since that way the same sensor is being seen by the ECU and to tune with.

Opinions/comments?

Thanks as always!

 

[MarkAngelo05]

I would go for it! Is your WB o2 sensor mounted atleast 30 inches downstream from the turbo?? I am about to do that with my plx devices wideband kit, but so far my stock o2 has been able to keep it very close to 11:1 ratio which is what my chip is programmed for. But it should be more accurate when you tap into the simulated o2. Also, you can keep your stock o2 sensor in it's place so you won't have to buy and fabricate a resistor box to keep the O2 sensor heater CEL from coming on! Let me know how yours works out!

Mark

 

[Calan]

If I keep the stock sensor wired up to prevent the CEL, where would I wire the WB's narrowband output?

And wouldn't the ECU see the WB's narrowband output as a stock sensor anyway, if it's wired into where the existing one is now?

 

[dcg9381]

If I keep the stock sensor wired up to prevent the CEL, where would I wire the WB's narrowband output?

And wouldn't the ECU see the WB's narrowband output as a stock sensor anyway, if it's wired into where the existing one is now?

You can't use a WB in place of a narrowband, their output and response is totally different. A NB is only accurate at 14.7:1.
Generally the WB operates on a different voltage scale, althogh some can be recalibrated - they still react differently.

Unless you're using a standalone or piggyback configured for the WB output, you should just use it for datalogging or for output to a gauge..

 

[Calan]

I'm not talking about using the 0-5v into the ECU...I was referring to the simulated narrowband 0-1v output that comes off of the unit, as a replacement for the stock sensor.

The 0-5v WB output will go to my logger via an unused ECU port, or to a gauge.

 

[98mitsuGSX-SD]

I use the narrowband output in replacement for the stock pre-cat o2 sensor. The wideband output is connected through the post-cat o2 for logging purposes.

to back up MarkAngelo05 post. Your going to want to install the wideband o2 sensor in your downpipe NOT in the stock pre-cat location. Due to the heat of the exhaust.

"If I'm tuning with the WB, but the ECU is still reading a "stock" narrowband signal, how does the tuning work out?"

For tuning purposes your be logging your wideband for WOT which causes the system to go into OPEN loop mode. You'll use the data retrieved from the log to adjust the parameters of fuel and air flow blah blah blah to achieve proper A/F ratio at specific rpm's.

and if any of what I said was incorrect please feel free to correct me.

 

[delta448]

I'm probably going to go with the ZT-2 WB when I finally buy one, I think you made a good choice. The thing I really find interesting is the ability to offset the narrowband output, so you can trick the ECU into running a richer or leaner AFR even if you don't have other tuning electronics.

 

[jumpfroggy]

If I'm tuning with the WB, but the ECU is still reading a "stock" narrowband signal, how does the tuning work out? If the narrowband isn't reading exactly the same and isn't as accurate as the WB, isn't the ECU gonna try to make corrections based on that, rather than taking advantage of the A/F changes that I make via the WB?

You could think of the WB and Normal O2 signals as high-resolution and low-resolution measures of the same thing. One is more accurate, but they should be in sync.

As to your question that they would cancel each other out, it depends on your tuning device. In and AFC setup, the AFC steps in between the (normal) O2 and the ECU, faking higher/lower air flows to trick the ECU into giving higher/lower fuel. In a DSMlink, you remap the tables in the ECU itself, so X measured air goes to Y fuel, which you can program.

You don't state what tuning device you have on your car, but for 650 injectors I'm assuming you're going to use the AFC (or MAF-T, maybe). The advantage of the wideband O2 is that you have "real" measurements to tune with (in .1 A/F increments) instead of the mostly on/off normal O2 (above 14.7, below 14.7). But this is a measurement, and does not by itself tune your car.

So this... if you see that you're .2 A/F above where you want to be, then you tell your tuning device (AFC?) to bring it up a big in that RPM range, then you'll be tuned. The fact that you're running off a normal O2 or simulated O2 doesn't make a difference here, the only advantage is that you know the exact A/F. You could "tune" the car the same way with just a normal O2, but you'd just be doing it blind without the measurements from the WB.

Make sense? Ask more, I may not have everything exactly correct but hopefully the idea is there.

 

[BISHILVR]

At anything other than wide open throttle your ecu will operate in closed loop and use the narrowband to try and undermine any mixture changes that you have enacted if those changes are outside of the ecu's acceptable ranges. I think that is what you want to know? You should just leave the stock o2 sensor installed and connected as factory, and then add the wideband as an additional o2 sensor as an aid in tuning for yourself.

 

[Calan]

I understand the closed loop/open loop concept. I guess I was just thinking more about closed loop... which after a little more thought... the wideband won't have any affect at all if I use the stock o2 sensor.

@BISH - that is why I'm thinking I should use the WB's narrowband output as a replacement for my stock unit; that way the same sensor is feeding both signals (albeit one narrow and one wideband). I think my stock o2 is on it's last leg anyway.

@delta - yeah... the ability to "offset" the AFR for closed loop sounds pretty useful.

@froggy - I'm using the MAF-T with a GM MAF.

As for the bung in the downpipe, I had one welded a couple inches in front of the flex coupling, pointed straight out towards the tranny. That was about the only place the guy could tap into without pulling the downpipe and risking broken bolts, etc... which I can't replace right now. I'm thinking I'll just run the sensor straight out, over the crossmember, along the clutch line and up into the engine compartment close to the battery. Should keep it away from heat and anything mechanical.

Eventually I'm gonna redo the entire exhaust anyway, at which time I'll probably relocate the bung to a better place... if there is one.

 

[MarkAngelo05]

Hey Calan,

The narrowband simulator is basically MORE ACCURATE NARROWBAND A/F Data, since it is being calculated by the Wideband o2 sensor. As far as wiring it to the ecu, just look at the ecu pin/wiring diagram and it should take the place of the FRONT O2 sensor. I believe it's the same wire that people tap NARROWBAND FLASHY LIGHT SHOW A/F Gauges to.

Good luck and keep us posted. Oh, does your manual tell you to install a capacitor between the ground and the O2 data wire to filter out any interference?? I know mine came with some capacitors and I will most likely install them aswell.

Mark

 

[Calan]

I haven't seen anything about the filter.

Mine came with caps, but it is because I asked for the free replacement ECU caps... at least that is what I assumed. Since they don't have any documentation, I don't know until I have a closer look at the ECU caps. There were just three small electrolytics in a ziplock thrown in the box.

What cap should be used for the filter? Any documentation on this?

Thanks

 

[MarkAngelo05]

Here you go bro, read this, In the installation procedures it will explain how adding capacitors help filter any kind of interference. Install it between ground and the o2 input into the ECU, as close to the ECU as possible. This site also explains the wideband and narrow band curve and how well the narrow band output on widebands work.

http://www.plxdevices.com/AppNotes/PLXApp004.pdf


Take care! And don't forget to post how well your setup works! When I get my car to run well, I'm going to do this so my ecu will adjust to a perfect 11:1 ratio as my chip is programmed to. It usually fluctuates between 11.5:1 and 10:1 which is pretty good, and it's weird because .95 on my NARROW BAND STOCK O2 SENSOR is 12:1 on the wideband... but if you look on the graph, this is why your stock narrow band is "not that accurate", it is pretty much a flat line at .95 volts from 10:1 to 14.4:1 AIR FUEL RATIO!! Imagine how much more accurately your ecu will adjust your a/f ratio when you feed off your simulated narrow band! Well, as soon as I get my other issues solved, I'm deffinately going to bypass my stock O2 sensor, plus this PLX unit comes with a gauge similar to AEM's UEGO but it is only 1/4 inch thick, and they have the Narrowband output! Was going to get Zeitronix, but opted for somethin simple with one gauge and a controller that can output wideband and narrowband voltages.

Mark