Does the Mini use narrow or wideband O2 sensor?

 

Both the pre and post cat O2 sensors are narrowband heated types.

 

Thanks Greatbear:smile:

 

I concur - narrow

 

So is this a good thing.Kinda know what you are talking about,but the more I can learn the better

 

I guess I will try to shed some light on the difference between the two.

As most know the O2, or oxygen sensor sits in the exhaust stream of an engine, measuring the oxygen content of the exhaust and hence the fuel mixture ratio after being burned in the engine. Since the beginning of their use (early-mid 80s) in cars, manufacturers have relied on a 'narrowband' sensor. What this means is that for a given optimum, or 'stoichiometric' fuel/air mixture of 14.7:1, the sensor cannot indicate much beyond a narrow range, or 'band' outside of optimum. In other words, the sensor has only a narrow working range of about 1 point above and 1 point below before the sensor can no longer measure it. The output signal 'hits a wall' and will no longer increase or decrease with the changing of the exhaust oxygen content. All it can say is a Goldilocks-like 'too rich', 'too lean' or 'just right'. Knowing what the engine is putting out in the exhaust is the key to knowing the amount of fuel to put in. This is called 'closed loop' operation.

Think of the sensor a lot like a traffic light. You have three indicators, stop, caution and go. Red, yellow and green. Except in our case, you have rich, optimum and lean, with little wiggle room. Think of 'closed loop' operation as maintaining your vehicle speed when driving. Say you are driving 60mph on the highway. You start to go up a hill. You notice that your speed is dropping and you press on the gas to maintain your speed. Likewise, going down the hill, your speed increases, so you lift your foot off the gas to keep from going too fast. You are operating the car in a 'closed loop' fashion by seeing the end result (your speed) and basing your actions and input (how much gas to give) accordingly.

The problem here is that in a typical gas engine, the fuel mixture needs to be a bit richer than the 'optimum' 14.7:1 value at full throttle for maximum power, usually on the order of about 12:1. Since the sensor can now only tell the engine control computer that the mixture is "rich" and not a specific value, the computer must estimate how much fuel to inject by using other measured parameters such as incoming air pressure, engine speed and throttle position.. Likewise, if the computer sees a 'lean' condition outside of the working range, it often 'overcorrects' to bring it back to normal. In reality the ECU is constantly seesawing the mixture between 'rich' and 'lean' trying to make the average end up in the middle.

Imagine your driving style if you had no speedometer and instead had three lights on the dash that said 'too slow', 'just right' and 'too fast', and there was only a mph or two different between them!

A 'wideband' or 'broadband' sensor is able to make an accurate measurement through a much wider range of mixture ratios. A wideband sensor can measure 4-5 points or better on either side of 'optimum', giving a meaningful measurement of the actual mixture. The ECU can better control the mixture knowing exactly what the end result of it's actions are to base it's decision as to how much fuel to inject. It's not just being told it's either too rich or too lean, or just right.

Wideband sensors have only been recently developed, and currently are very expensive. Expect to see their adoption in cars as the technology improves and becomes cheaper. The MINI currently uses a narrowband sensor, as does just about all cars on the road now. Wideband sensors are used now as test indicators by manufacturers and engine tuners during the development of fuel injection systems and software that controls them. There are also high-end fuel injection systems that use wideband sensors to regulate fuel mixture. These are generally used in racing applications.

I hope this helped a bit. But I somehow feel I made it worse.

 

Thanks. That's interesting.
I suppose as costs decrease JCW or somebody will incorporate wide-band into a retrofit to give better results during acceleration. Something to look forward to, if I understand correctly.

 

Once again,thank you Greatbear for explaining something so even I can make sense of it,on the first read

 

Great writeup Greatbear I became interested in this subject while researching the current crop of air/fuel gauges using wideband O2 sensor such as AEM, Dynojet Wideband Commander, PLX, etc. Looks like a new O2 sensor bung would have to be welded on in order to use one of these monitors.

 

I just recently installed an O2 guage... mainly to monitor what's going on with my 19% pulley. I can tell you that by splicing into the factor pre-cat sensor, my readings constantly swing between "Lean" and "Rich" at a rate of about 1 cycle per second in closed loop (cruise mode). It does not swing between extremely lean and extremely rich though. At WOT (open loop), it will peg into the rich, and as RPMs build, drift back to ideal, and barely into the lean as I tag the rev limiter. I estimate the last 1500-2000 rpm or so, are a bit leaner than the motor would like... closer to an ideal mixture, but leaner than a boosted mixture really needs.

In reading it during closed loop/cruise mode, I simply imagine where the mid-point of the swing is... right or wrong, I don't know, but that's how I read it.

I'm curious... if I install a wide-band sensor, would I get a no-swing, spot-on reading during both closed loop and open loop? Anyone?

 

That's exactly what you get with wideband...no swinging lights...some even have digital readout of the current A/F. I understand that a wideband converter is made for the Autometer shrtbnd meter.

 

Innovate Motorsports has come out with the first relatively inexpensive wideband a/f ratio meter. It's a handheld portable meter that uses a Bosch wideband O2 sensor as input. To use this in a typical car, you need to weld a bung into the exhaust prior to the cats. It appears they are coming out with a panel- (and possibly surface-) mounted gauge version soon too.

You cant simply replace the existing O2 sensor in a car with a wideband type since the output signals are completely different. Unlike the 0-1 volt narrowband signal centered around stoich, a wideband sensor has a larger voltage swing closer to 0 to 4-5 volts if memory serves. The ECU wasnt designed around such a signal and would see the hugely out-of-range signal as a fault condition and throw a code. You would need a converter which would take the signal from the wideband sensor and scale it to simulate a narrowband sensor. In such a case you have negated the benefits of the wideband version, though the unconverted signal direct from the sensor can be used to drive an indicator without having to weld in an extra threaded bung.

To be able to make full use of a wideband sensor, the ECU has to be able to accept the wide-swing signal from the sensor as well as be programmed to remain in closed loop during open throttle conditions where open loop and fuel maps are currently being used. It's not a huge change, but it may or may not require hardware changes (depending on the dynamic range of the O2 sensor input circuitry) to go along with the obvious programming overhaul needed.

 

I decided to revive this thread because there are so many other ones like this.

Since the Mini uses a Narrow band O2 sensor I am going to get a wide-band sensor before I start modding my Mini to make sure I don't run lean.

My question is this. Does a wide-band O2 sensor measure 'all oxygen and carbon-bearing gasses' or does it only sample the left over O2? (reference at http://www.bridgeanalyzers.com/Docum...0Paper%201.pdf ).

I am trying to decide if I should get a gauge that displays Lambda or regular A/F. If a wide-band O2 sender only samples the left over O2 then isn't a A/F meter that can display Lambda like the Gauge Type Wide-band UEGO Controller at http://www.aempower.com/product_ems.asp not displaying true Lambda calculations? Should I just get the model that displays A/F?

What do you guys think of the importance to be able to log the data? I can't decide between a logger like the one in the post above that I don't keep in the car all the time or the AEM gauge.

Brad

 

There are several very good WBO2 kits on the market and one of which I know PLX Devices. Their models have both narrowband and wideband outputs. Ford guys have been swapping their OEM O2 with the one from their kit (Bosch or NTK which ever you order) and tap the NBO2 line going to the EEC and use the kits output with no ill effects. You then have the WBO2 driving a display. Their newer models have software for datalogging A/F and they even have wireless models.

If you want to know more about how these signals work, there's a lot of info on some of the Ford boards. The NBO2s signal as Greatbear stated switchs rapidly between +/- 1V (hystersis curve) for the exact purpose of realtime control of air fuel. WBO2 has a wider voltage range and sampling rate for exact measurements. That's a quick summary of the difference.

Hope I haven't added any confusion.
Wayne

 

Actually, all the new VW's utilize wideband sensors (a bosch part as well, like many of the aftermarket meters use). While the aftermarket sensor usually cost several hundred dollars the VW replacement sensor is somewhere in the neighborhood of $40. The Mini uses the same basic engine management as the VW, and so it has provisions for a wideband. In fact you can read the output of the VW sensor to the ECU in 2001+ volkswagens, if you know the memory locaction and have a method to communicate with the ECU, and it is extremely accurate. There is no longer a need for aftermarket tuners for these cars to even utilize an aftermarket wideband for A/F tuning any longer.

 

Does anyone know of a converter that would make an Autometer N/B gauge be more accurate when hooked up to a mini? At the moment, the thing looks like a graphic equalizer in my mcs

 

Great Job on why the O2 sensor is the ring master in close loop
If its not broke why fix it

 

great on the spot write ups. I understand now. The way I see it, atleast it's much less expensive to replace

 

I had hoped the o2 sensor on the mini was wideband, as mattharris75 said, more new cars have them from the factory. I know honda uses them on their K-series engines.

Maybe they chose not to use a wideband because our MCS's run pig-rich, which is known to foul wideband sensors quickly. Any other ideas?

 

Wouldn't the primary advantage of a wideband be the ability to run pig perfect? Rich enough for a little protection, if desired, but not rich enough to foul the sensor. How does the wideband control the fuel mixture if not like an "on/off" switch? Sorry for the ignorance.
mike

 

What kind of gas mileage are ppl getting after a wideband o2 conversion on their r53's?