Exhaust Gas Analyzer 1

[redeyerighley]

Hi Guys,

I do my own tuning of my 2 stroke off road bike, I would like to add an exhaust gas analyzer to my arsenal. I am lookig into building a dyno, and have found plenty of info on this topic. I would howevere also lik eto look into a exhaust gas analyzer. Has anybody ever built their own exhaust gas analyzer using a lamda or wideband O2 sensor? Also, if anyone has built their own data aqcuisition system for use on a dyno that would also help.

Best regards

 

[BrianPetersen]

Haven't done it, but on a 2-stroke engine, expect the short-circuiting of raw air/fuel across the piston to cause a wide-band sensor to read a false lean condition. I've not seen lambda or wide-band sensors used on 2-stroke engines. (I have one for setting up my four-stroke bike engines.)

 

[patprimmer]

Why would it read lean when there was unburned fuel in the exhaust. I am not being sarcastic (well this time). I really do wonder why.

Regards
Pat
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[Lou Scannon]

The sensor may eventually foul with carbon and/or oil. Of course, it can be replaced.

 

[BrianPetersen]

The sensor measures oxygen, not fuel. An unburned mixture of air and fuel, even if it is chemically stoichiometric or rich (just not burned), is read by the sensor as lean.

 

[patprimmer]

OK that explains it.

I guess they measure oxygen in the lean to stoich range and CO in the rich range.

Regards
Pat
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[Lou Scannon]

There's a little more to it than that. I'll give the Cole's Notes version. A UEGO sensor has a standard zirconia sense cell that operates at lambda=1. There is some intricate circuitry onboard the sensor as well as off-board on the controller that functions to control two pumping cells that are incorporated into the sensor along with the sense cell. The pumping cells are controlled to pump oxygen into or out of the sense cell to maintain the sense cell at lambda=1. The sense cell is sampling the exhaust gas, of course. The current required to pump oxygen into or out of the sense cell is measured and correlated to the percent oxygen in excess or falling short of lambda=1.

 

[patprimmer]

All that in one little device that operates reliable with good durability at exhaust gas temperatures within a few feet of the exhaust valve. Incredible.

Regards
Pat
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