Narrowband and Wideband - which more accurate?

[articzap]

Car: 2006 Cobalt SS/NA
Engine: LE5
ECM: E67

The car has a Vibrate 4-2-1 header. The header has the narrowband mounted in the "2" section, so its effectively only reading 2 cylinders. Wideband is placed about 6 inches lower on the downpipe.

Both ECM stoich and wideband stoich are set at 14.7. Fuel trims are within -3%. Narrowband should be seeing a perfect 14.7 that it's striving for. On the other hand the wideband reads at 15.3.

Which one is more accurate? I want to say the wideband, just based on where it's located, although I've heard theories both ways.

Second, if the wideband is more accurate, is the best way to sync the ECM to the wideband by dropping the stoich in the ECM until the wideband reads 14.7?

[laser_racer]

Okay not sure where you got that info but wideband is so much more actuate then a narrow. Your car is never going to hold a perfect stoich ratio reading with fuel trims working. Another thing the car doesn't always command for a 14.7 even though stoich is set for it. The car can command for other afrs depending on what it needs like piston protect or cat warm it will set the stoich to a rich condition tell it says its all right. You need to add command afr on your scanner to see what car is asking for.

[articzap]

Car is commanding 14.7.

[HNRClothing]

NB 0-1 volt - WB 0-5 volts. WB is more accurate.

[5_Liter_Eater]

I've seen where the WB reads leaner than the NB and for me it was due to tiny pinhole air leaks in the WB bung.

[Leafy]

Theoretically a narrow band is much more accurate than a wide band while very close to lambda 1 because it has a relatively large voltage swing for a tiny lambda swing. I had it somewhere that described the differences in resolution and I cant find it this early in the morning. In your case its harder to say. Though if you have an innovate wide band it has one output set up defaultly to be able to replace the narrow band. I dont like the idea of doing it but if your narrow band is really reading only 2 cylinders then it may be a good idea.

[Iam Broke]

I found this chart in the LS1 section when I started logging a narrowband on my WS6, IDK how much I'd trust it for tuning though. My LS1 ran .900 mv at WOT on the stock tune.

[Leafy]

You cannot use the narrow band to tune anything that's not closed loop. It has zero accuracy at anything that's not close to stoich.

[articzap]

You cannot use the narrow band to tune anything that's not closed loop. It has zero accuracy at anything that's not close to stoich.

Well that's more then obvious. But with regards to strickly stoich, which is more accurate is the question. Please re-read before posting.

[Leafy]

Theoretically a narrow band is much more accurate than a wide band while very close to lambda 1 because it has a relatively large voltage swing for a tiny lambda swing. I had it somewhere that described the differences in resolution and I cant find it this early in the morning. In your case its harder to say. Though if you have an innovate wide band it has one output set up defaultly to be able to replace the narrow band. I dont like the idea of doing it but if your narrow band is really reading only 2 cylinders then it may be a good idea.

.

[obiseancanobi]

I have replaced my factory O2 sensors with the LC-1 wideband. The analog 1 on the LC-1 output is wired to the factory harness to simulate narrowband. With the factory narrowband the B1S1 and B2S1 graphs looked different than they do now.

The factory narrowband graphs were more smooth. The LC-1 has the same sort of pattern yet it is not as smooth and the graph looks a bit erratic. Does anyone know if this behavior is normal or if it can be tuned, adjusted.

[Leafy]

Did you set up the LC1's to output analog 1 with instantaneous and not 1/6 or 1/12 in the advanced options I cant remember what its set up from the factory. But to simulate a narrow band it should be set to instantaneous and for a wideband output it should be set to one of the averaging settings.

[obiseancanobi]

Thanks. I will check that I didn't change anything from how it came from the factory. I did just read this on the Innovate site.

If you click on the ADVANCED button, you can change the Response Speed of the sensor. Too fast of a response speed will cause your air/fuel data log to be sporadic. Too slow of a response speed will be less accurate. You want the fastest speed possible that creates a smooth enough data log to be readable. I would start with “1/12 sec“ and try it. If that‘s too sporadic, try “1/6 sec“. The “Instant” setting is too fast, and causes Live Link to show a jumpy Air/Fuel ratio.

Sounds like what I am experiencing is because it may be set to instantaneous. I'll try tuning that to see if the graph smooths out.

[obiseancanobi]

I setup the LC-1 for a 1/6 delay on the narrowband simulation. It looks more like a smooth'ish' sine wave now. A little different behavior still than the stock oxygen sensors. However, it still appears to be keeping stoich well.

I have the Analog 1 output kept at stock (0.103V = 1.022 and 1.100 = 0.958). The difference in behavior from the stock O2 may be the slightly different characteristics of the wideband sensor?

[silverbullet08]

Heres a out of the box answer to your question... I met a guy at a car meet about 6 months back having a lean issue with the same car your working with. He had the same header design your talking about the 4-2-1 with the front 02sensor monitoring i believe only the outer two cylinders 1&4. Well I get to talking to him about a tune and he says this is his third motor in the car. So I asked what all mods he had and the only thing done was the full exhaust including the header. Every motor he had burnt a hole in piston 2 so i thought it was the injectors. I told him to give me a call and i would diagnose it and do a tune on it. 2 months later he called me and it had another melted piston. I did a motor swap for him and swaped in some new injectors and fuel rail with a new injector harness. After i started it 5 mins later it had a lean code again. I put my wideband in it about 6 inches past where all the runners merge and it said everything was still in check at about 14.8-14.9ish. So i did a full maf tune on it. It needed another 6% fuel over the entire curve from factory. Some areas were up to 8-9% lean but the entire time my wideband said it everything looked good. I looked throught the tune and there was nothing to add extra fuel to a individual injector and we dont have control over individual cylinder timing so i couldnt play with that. My thought was not having the two center cylinders to be monitored by the front 02 causes too much of a variance.

[obiseancanobi]

I have the Dynatech SuperMaxx headers 4-2-1 design. The upstream O2 is located just after the header to midpipe flange right next to the cat. So it's definitely getting the full 4 banks reading on each side.

The wideband O2s are working good in my opinion for narrowband sim right now. I may go back to the stock O2s upstream once my tuning is complete.

Attached my latest tune if you're interested. I am doing a little SD tuning right now so the MAF is disabled in this tune.

Overall car runs good and strong over the last 4 months with the latest upgrade being a Vortech centri supercharger. Also installed on the vehicle for several years now is that LT header system with high flows cats, Volant cat-back, AirAid box, and also 47# injectors, plugs, wires upgrades.

The only odd thing I have noticed after the supercharger install is a strange ticking noise at times when I put the truck in reverse or sometime upon deceleration it also makes that similiar ticking noise until coming to a full stop. Also when downshifting for engine assist deceleration the vehicle gets a little jerky; moreover, reving the vehicle in park to a sustained RPM, say 3000 it doesn't hold steady. Almost like a boost surge.