Bosch specifications are out there, but they are hard to read until you spend some time with them. There are also several versions of the documents to be found and the ones we have had to be signed for so I cannot post those up. The BroadBand sensor is a NB sensor with added circuitry. One of the things you have to remember is the sensor is trying to measure the O2 in the exhaust and compare that against the O2 in the surrounding air. It does fine while there is extra O2 in the exhaust (Stocih to lean reading) but what happens when your mixture goes rich and there is no extra O2 in the exhaust to be measured?
In basic terms, the pump area of the Broad band must pump O2 into the sensor until it dilutes the sample enough to get a reading of O2. That takes time, once it can read it then compares how much it had to pump to come up with a reading.

Obviously I made a very simple way to cover how it works but that should give you the basic idea of why it is and will always be much slower than a direct reading take by a NB.

 

Even narrowbands have an issue reading in a over rich exhaust! Proved that to my self. I had to manually change the fueling tables till they effectively came on line reliably.

 

I understand the O2 part.. The pumping thing is real interesting.. So the sensor sort of measures the amount of 02 added to get the a narrow band sensor to switch? That amount determines what the sampled O2 level is?

 

As Tsani said earlier, the 4.9s don't use reference air and are supposed to be a lot faster if you believe the Internet that is
http://www.ecotrons.com/technology/b...su_42_sensors/

Bwaltz The exhaust flow to the cell itself I think I read that was improved by having more holes in the outer cover but the sensor should effectively be in the exhaust flow at all times, distance from the cover to the cell should be negligible unless you're thinking about the air flow dynamics and a pocket of gas within the cover that is not getting refreshed properly ...that would be down to sensor placement and angles etc (just guessing here).

A "blip" of the throttle ...sorry, the language barrier, no idea what you call it over there ...I meant just a quick short turn of the throttle and let it straight off again??

 

Are you sure about that? I thought it used the reference air and compared the reading between that and the exhaust to get the number?

EDIT: a bit old but this explains (if you believe the Internet) what the pump cell does http://wbo2.com/lsu/lsuworks.htm

 

Remember the name of what we are talking about "O2" sensor. It measures O2 levels, and a few other things, if you have no O2 to measure then what can it do?

I have tried to simplify some of what is really going on to give people a general understanding of why it works the way that it does.

If some of you would really want to dig deep into exactly the interworkings of the Bosch LSU series sensors here is what I found floating around the internet from Bosch for specifications. While they do not contain everything you need to know, it's a good start to see if that is the direction you want to go. I've also include a nice document from Motec on there controller unit as it contains some good information in it about mounting, heat and pressure, along with various fuels and how they effect AFR vs Lambda.

 

"to get the a narrow band sensor to switch?"
If I inderstand it correctly...
The sensor has no and is no switch, just outputs voltage.
The ECM determines a rich voltage and leans the mixture until it reads a lean voltage then the system enriches the mixture until the system reads rich then it enleans the mixture until it reads lean so the system switches from lean to rich to lean to rich, etc.
Bob

 

Interesting that a lot, if not most, of the install sheets show a straight rather than an angled bungs??

 

Absolutely correct. This is why it is a mistake to view the sensor as a switch. The ECM and its programing is doing the "switching" of the fuel pulses and the switching action or more correctly, indication, is seen in the O2 Sensor output readings. Correct terminology is definitely a plus. It is like a physics teacher I had who would not accept an answer if stated as a number only. It's a number, it does not indicate anything with a proper description. Once the O2 sensor is warmed up properly, it is constantly outputting a MV reading. It does not switch anything. Also keep in mind that what you are seeing in the O2 readings is an after the event result and always will be.

 

In the real data sheets they recommend putting it straight too! There is a foot note that states you can do whatever you like as long as it gives you a proper reading and follows the other guide lines, but it is all up to the installer to prove what they have done works! In HD's case with a cat and restrictive mufflers what they have done works, remove the cat and put free flow mufflers in place and who knows what's going to happen.