Wide band lamda probes - pros of them?

Yea but the rolling roads also use a wideband probe & controller to measure the same thing. So the same possibility for inaccuracy exists there too. Only difference is that you can safely replicate conditions on a rolling road (to a point) to help diagnose/map the engine.

Gurds

Gurds

 

The DD dyno uses a specific narrowband sensor to perform tailpipe the measurements. The interafce box does the conversion to 0-5v and the dyno software converts to AFR or lambda. You can also use a planer sensor (wideband) with a control box and output the dyno PC. After the controlbox heats up the sensor the system uses the sensor signal to calibrate itself to free air as the reference. This similar to what PLX, Innovate do with their systems.
When tuning on the rolls keeping spark timing constant, the absoulte lambda number does not matter as I can see the tractive effort increase or decrease for a change to fueling. The AFR reading for that given tractive effort increase is taken as the "optimum" for that iteration. I can also DAQ out EGO measurements to make delivery of the calibration process more complete. The absolute AFR number matters very little then. It would be the indicated. Bare in mind, the numbers seen in the feed gas exhaust are really and indication of what WENT ON in the combustion chamber. This delay and quality is made worse the further away you place the sensor up the exhaust stream, typical of how it would be on a chassis rolls.
I would like to think that for max torque (fuel only) for given speed/load in a gasoline engine you need to be at 12.5:1 generally. But in reality this can vary from engine to engine and from speed/load site to site from 12.1:1 to even 13:1. The saftey of a chassis rolls helps to determine this very quickly.
The accuracy of the lambda reader or how close it is to an absulote or reference value may matter if you think to need to achieve a certain AFR, based on what is seen in a book, forum or mate, for max power and you are road mapping w/o prior access to a rolling road and some its readings. The danger this this method is each engine will have different fueling requirements and if your sensor or controller box is sending out erroneaous readings to the gauge then your calibration settings can be incorrect and can lead to a dangrous or poor running conditon.
It does not mean to say that live mapping cannot bring out the general character of an engine. I have learnt the general behaviour of quite a lot of vehicles by live mapping and even fettling with hardware. I still do this to this very day. The WOLF R was mapped mostly on road with both LM1 and VEMs in car readings and gtech-pro for accel traces. It only had some dyno optimisation for the first time on Wednesday night.
Now and fortunately for me, portable tools like my LM1 can be checked on the dyno for measurement deltas to avoid such issues. I have also found that the tailpipe measurements can vary by as much as a point compared to if placed nearer to mainifold collector or turbo downpipe.
In my opinion the use of a lambda reader should be used with another means to accurately track the vehicle acceleration at WOT. This way you can see and feel( probably) any changes as you set up a control map. The value should be accurate enough but not absolute.

 

That's what i run on the Corrado, permanently wired in to show readings on a gauge and also feeding the original ecu via the narrow band output.

It's very! responsive, i've changed the ratio of the output to slow it down a little and make it a more readable average on the gauge.

You will more than likely need to buy one of these if intending on hooking the laptop up.

Neil.

 

good read

 

That's what i'm looking into for mine