I'm new to tuning, just getting started actually, and I have been doing alot of reading and research. This may be a really ingorant question but I'm just trying to get all the info I can. Through working on cars in dealerships I know scanners show live feed from o2 sensors. I presume from what I have read about it so does AutoTap (the program I am looking into for my 96), so why the wideband? I understand they are just a real time update for fuel mixture that you install into your exhaust. What are the advantages to wideband over just reading the info from the o2 sensors?
Drew

 

The stock narrow-band sensors are not accurate at anything other than the stoichiometric A/F ratio of 14.7:1, +/- .10 A/F ratio units (14.6-14.8:1). They are used ONLY to keep the engine at 14.7:1 in closed loop, because that is the A/F ratio that produces the lowest COMBINED total of CO, HC and NOx emissions. That is the A/F ratio the catalytic convertor is designed to operate at. It also gives decent fuel economy, although you could do better with a leaner mixture. But that would drive up the NOx to unacceptable levels.

But when you want peak power, or peak torque, the stock programming sets a richer target A/F ratio, and ignores the feedback from the narrow-band O2 sensors, because they are not very accurate. If you look at the output curve for a narrow-band sensor, mVolts out vs. A/F ratio, it will be a reverse "Z".... very flat (large changes in A/F ratio produce small changes in mV's) below 14.6:1, almost vertical (small changes in A/F ratio produce very large changes in mV's) on either side of 14.8:1, and then flat again above 14.8:1.

For peak torque/HP you are usually looking at A/F ratios in the range of 12.8-13.2:1. At that level, the narrow-band sensors are more sensitive to temperature changes than they are to actual changes in A/F ratio, rendering them inaccurate.

The wide-band sensors are accurate over a range of 10-20:1 A/F ratio. Output is typically 0-5V, in a fairly linear manner. That is the only way (short of more sophisticated lab quality instrumentation) you can accurately measure the typical A/F ratios used for normally aspirated engines (12.8-13.2:1 as noted above) or with forced induction or nitrous engines that require even richer A/F ratios.

Short answer - because a wide-band sensor will be more accurate at the A/F ratios required to produce serious power.

 

Thanks alot for the info I'm new just getting into tuning and looking for all the info I can get right now. Are there any specific brands you would recommend I've already been told LC1. I'm sure I'll find out when I have the time to research it but currently I'm short on time. Do you drill and tap a hole in the exhaust pipe and install similar to an o2 sensor and leave it there permanetly, or hook it up to the tailpipe, or what? I understand it wouldnt be accurate at the tailpipe with cats but I have none. It may be a dumb question but I just haven't had the time to research it yet and its quicker to just ask your opinion.

 

You have a few choices.

1. Install a 2nd O2 sensor bung in each side of the exhaust.

-Plug the bungs and install the wide-band only when tuning. A wide-band sensor does not have the same, long life expectancy of a narrow-band sensor. Why wear it out if you don't need it.

-Leave the wide-band on one side, and plug the other side, switching the sensor from side-to-side periodically, when you see the need to look at the other bank.

-Get a dual sensor controller, and have the ability to monitor both banks at the same time. Now you are looking at $600-750.

2. Replace the stock narrow-band sensor(s) with a wide-band controller that has a narrow-band "emulation" (0-1V) output, that can feed the stock PCM. This will work with either single or dual wide-band sensors.

3. Use the wide-band only for dyno tuning, by pulling a stock sensor out and installing the wide-band in that bung.

FAST and Altronics make interesting dual wide-band controllers:

http://www.rpmoutlet.com/mt.htm

http://www.altronicsinc.com/pages/o2alert.html

http://www.jegs.com/webapp/wcs/store...15051_10625_-1

 

I use the LC1 - have been very happy with it... The LC1 has the narrowband emulation feature, also.

 

Alright thanks for the help Ill look into that stuff and see what I like best.

 

What wire do you tap into for the narrow band emulation on the PCM side?

 

I don't have my LT1 PCM wiring diagrams in front of me, but it is the O2 sensor high signal. But, in order to get this to work, the O2 sensor low signal must be grounded to the chassis because the LC-1 only has the analog positive output.

 

o.k. so If I set my AEM to position4 it puts out the following

10:1 AFR .905 volts
18.5 AFR .070 volts

So I can hook my analog output to the huego wiring and ground the huego ground to the pcm case ground?

If this is correct, how do I find what huego sensor is the active and what one is the ground? It is a 4-wire square plug. This is on a DFI gen7

 

I have a question on the LC-1 I have that kit also do I nee to do the free air calibration for first time use? or just put it in ans call it good

 

Sorry, don't know the pin-outs for the 4 pin square plug...

Yes, you want to do a free air calibration with the O2 sensor uninstalled. You can do a free air calibration with it installed if the engine hasn't been run in the last 6-8 hours according to the LC-1 manual.