Narrow and Broad band O2 sensors and open vs close Options

[lmcchesney]

Sorry guys, but I've been doing some reading again. Dave, you and I have had some of this discussion before and I would respect your continued thoughts on this setup. The crux of the matter requires understanding of the circuit utilized to turn the lamba analog data into useful information. Well, here goes.
O2 sensors in a distal position provides indirect input for the estimation of the A/F ratio seen by the engine. This information is useful in defining a lean or rich mixture seen by the sensor for the most recent peroid of time. Broad band O2 sensors are capable of producing a wide range of output voltages which can be inturpeted for measuring the ratio. In fact, the output from broad band sensors can be feed into the Electronic Control Unit several times a second. This allows for real time adjustment of the A/F mixture. Thus output from the O2 sensor is recieved as input by the ECU which inturn alters injector time/volume to preprogramed mixture. This feedback/adjustment defines a closed loop system.
Narrow band O2 sensors also read A/F ratios. However, A/F mixtures ranging from 13.7:1 to 14.4:1 results in a change in voltage output from lowest to highest (0.1v to 1.0v).
If you use a analog voltmeter or equalivernt A/F gague, the response rates are such that your readings bounce requiring seat of the pants estimate as to where the mean is.
However, with the use of circuitry involving a IC unit, the voltage output can be lengthed to a series of LED's.
My question, can not a narrow band O2 sensor be utilized to monitor A/F ratios throughout the power band. Noting the results, provide information for enrichment/leaning in the adjustable ranges of D-jet. ie, idle, partial throttle and WOT.
Cannot in dash monitoring with such an A/F circuit be helpful to identify serious alterations in the engine and prevent damage from excessively lean running?
Cannot the useful information from such an A/F monitor be inproved by silmiltaneous monitoring of CHT/oil temp?
I still do not understand the advantages of a broad band O2 sensor when used in a open loop system.
I cannot also see the significant advantage of a heated O2 sensor for monitoring the A/F ratios during that first 3 minutes.
Thanks,
L. McChesney

[DNHunt]

L

Several things to consider: 1)What is your target A/F ratio? 2) What is the value of an 02 sensor? 3) How can you use the information? 2) Which type of sensor provides the information you need?

1) The A/F ratio changes with load and RPM. Mine is targeted between 12.5 and 13.7 because that is the range that provides proer cooling and reasonable performance. It is a fact of life with aircooled engines that they must run rich or they burn up.

2)The value of an O2 sensor is that it is a tuning device whether you manually adjust the fueling or the ECU does it. Along with temperature (especially exhaust gas temperature) it gives you insight into how efficiently the engine is running.

3) You can use the voltage from the O2 sensor to adjust the airfuel mix: 1) by viewing the data and manually changing the injector opening times (hard to do on the street as load changes plus you gotta drive) 2) by datalogging and changing the points that are outside of the target later 3) by letting the ECU do it closed loop (fueling table must already be close)

4) Wide band is the only option because the target A/F are not anywhere near the range a narrowband covers. Sorry about that but it is afact of life for aircooled engines. You tune blind with a narrow band.

Dave