Wideband O2 sensors

Supercharged 無限MUGEN BB1 Profile · Post by **nucleustylzlude** » Wed Jul 03, 2013 8:58 am

Roughly speaking as far as my knowledge goes…

A wideband shows the accuracy of the lambda reading in more detail which is ideal for tuning purposes. Our P13 ECU's run in a mode called closed loop, this takes a typical fuelling map and will interpolate between readings to give a fuller, smoother map - if that makes sense? So it only needs a narrow band sensor to give high level lambda readings to run in closed loop. But when you tune, you need to work in open loop, which can have a wider range of fuel map parameters and doesn’t interpolate between readings. In terms of real time tuning (and running), a narrow band wouldn’t give you enough information. However, it would take a lot of dyno time and street tuning to fully map a car and leave it in open loop, so most will tune as much ‘map’ as they require to a desired Lambda range for either reliability or power goals and then switch it back to closed loop to again ‘read between the lines’ and give an overall smoother running car.

I think that’s the gist. Again, I’m not a tuner just know enough to get by. If any of that is slightly off, please shout!

89 UKDM BA4 4WS (resto job!) · Post by **wurlycorner** » Wed Jul 03, 2013 9:21 am

That makes sense.
Closed loop (feedback) control systems I remember and understand

A1ex · Post by **A1ex** » Thu Jul 18, 2013 1:00 pm

Ordered one of these today;

http://www.plxdevices.co.uk/product_inf ... ea021ca75c

FrontBackSide2Side · Post by **FrontBackSide2Side** » Thu Jul 18, 2013 2:58 pm

wurlycorner wrote:What's the point/difference of a "wide band" lambda sensor over a (presumably 'narrow band'?) one?

Basically the stock narrowband sensor can only read between certain air/fuel ratios. Factory maps are quite lean to conform with emmisions and get better mpg so if you start tuning your engine you will want to run it a bit richer to make the most power. These richer ratios are out of the range of a narrowband sensor so a wideband is needed as they can read a wider range of ratios. Hope that makes sense

Confused · Post by **Confused** » Thu Jul 18, 2013 4:15 pm

A narrowband lambda sensor basically switches from 0v to 1v output as it crosses over the stoichiometric mixture point - which is an Air To Fuel ratio of 14.7:1

This switchover is very quick, and occurs very close to 14.7:1

As such, you cannot know anything other than whether it is "rich" (more fuel, ie 12:1) or "lean" (less fuel, ie 18:1) - the standard ECU uses 14.7:1 as a target and constantly adjusts the fuelling and ignition timing to keep the output from the lambda sensor alternating between 0v and 1v - the more often it alternates, the closer it is to 14.7:1

When you are tuning, however, you will want to know exactly what your AFR is - you can only do this by having a wide-band lambda sensor. This will give a much larger output (typically 0-5v) which will vary based on the current AFR to a known scale - for example, 0.7v = 19.2:1, 4.6v = 11.8:1

With this more useful output, you can adjust the fuelling/timing so that under certain conditions, you have a specific AFR. Too much fuel is just as bad as too little fuel.

toyracer69 · Post by **toyracer69** » Sat Jul 20, 2013 1:10 am

A1ex wrote:Ordered one of these today;

http://www.plxdevices.co.uk/product_inf ... ea021ca75c

Nice.

I used to have a generation 1 version.

Lude Generation

Wideband O2 sensors

Re: Wideband O2 sensors