lambda sensors

Rich H · Post by **Rich H** » Mon Jun 18, 2007 9:29 am

Morning,

Question for the electrical wizards:

Narrow band senders genorate a voltage which changes from lo to hi (Or hi to lo I dunno) at 14:1

Does a wideband do the same but without the step jump? What does the controller bit do?

Cheers
Rich

Rich H · Post by **Rich H** » Mon Jun 18, 2007 4:06 pm

Bump....??

steve_weegie · Post by **steve_weegie** » Mon Jun 18, 2007 4:40 pm

Hmm, not sure myself. Best i can do is the wikipedia link

http://en.wikipedia.org/wiki/Oxygen_sensor

Lawrence · Post by **Lawrence** » Mon Jun 18, 2007 5:30 pm

Narrow band only measures at stoich 14.7:1 and provides the ecu with only too rich or too lean information, usually above or below 1v

Wide band measures from around 10:1 to 20:1 the box converts it to a linear signal usually 0v to 5V with 2.5v often the 14.7 figure

robin · Post by **robin** » Mon Jun 18, 2007 8:40 pm

Wideband operates on an active cell (controlled by a current) and a normal-type O2 sensor. The controller monitors the output of the O2 sensor and feeds current to the active cell to return the output to normal. Thus the current tells you how rich/lean the engine is.

The current isn't linear w.r.t to AFR and the slope changes around the middle. However, the result is easy enough to convert into a linear output, but accurate calibration is required.

Actually, narrowband sensors do provide something other than a step change - the problem is that the tolerance of the slopes away from the centre is so wide that you can never tell where you are - you would have to calibrate each sensor and even so it would be rubbish - so only really useful at the cross over point.

Cheers,
Robin