Right im not the most technically minded person but...

 

Am i to understand that the o2 sensors measure the oxygen level in the exhaust gas and then adjust the fuel mixture if the level of oxygen is outside the parameters??

 

Basically my car has an interesting issue where sometimes on the motorway it pulses ever so slightly..

 

So i hooked it up to my conzult, and also datascan and whilst crusing the o2 sensors are giving erratic readings. (seemingly at any speed)

Right is worse than left.

 

But under acceleration both seem to return towards the top of the scale

Under deceleration (or just coasting, no throttle) the both return to zero, or about zero.

Also noticed the fuel mixture is running rich lean rich lean rich lean etc etc in time with the erratic readings.

 

Does anyone know what they should read, and also i presume they are fairly simple to replace, and cost??

 

Or is this normal and its somthing else thats causing the slight pulsing.

 

By pulsing i dont mean accelerating and decelerating by any real measurable amount. it just a very subtle change in engine/exhaust note.

 

 

Just to add, fuel consumption isnt particularly horrific. Averages about 18 to 20 around town and mid to high 20's on the motorway.

 

Thanks guys!

o2 sensors will swing from rich to lean if they are working correctly, should swing quite rapid as well.

oops and on wot they should be showing rich

not quite sure what you mean mate.

Do you mean when reading a high voltage the car should be running rich?

 

Just seems odd that they swing from low to high and it switches between rich and lean when cruising? Or is this normal and im just imagining things?

over 2k rpm the o2 sensors will sweep from rich to lean. its exactly what they supposed to do for accurate fuel to air ratio. a lazy o2 sensor will be slower in the sweep or not work at all that one should be replaced if the fault is present.

ahh right, hmmm i shall have to study them more carefully then. Maybe its the one i thought that was ok is a bit dead.... Cheers guys!

because they are narrowband then when we go wide open throttle they are basically useless and the ecu ignores them at this point anyway as all they will show is rich( well they should)

ahh, all very interesting. Thanks for that :)