Hi Matt and Art,

You are right Art, I meant to said it should hover in the middle more of the range.
I was not clear in how it's response is.
I should have said not stay at either end of the spread. This way you know it's not dead and the car is adjusting.

Yes I have to agree, at idle!
I have not tried to hook it up to go into the cabin and watch it going down the road.
Since these things were made to help pass idle smog tests, for my state during our manufacturing years, that is all I expected it to be used for.

It is a box with 10 LED lights that blinks each tenth of a volt. So it flashes up and down very rapidly. No digital display time lag! Very little loading on the sensor circuit, as far as I know?
I have not opened it up and took a peek, yet! (:)
It's like a drag way "Christmas tree" except it goes both ways.

You can tell if its slow or lazy per say. A miss fire or an air leak can really swing good sensors to one end or the other! The 02 sensor is the heart of checking the tune and correcting a tight zone, at idle? That is all I can say about it worth?

It is made by Actron. It was a JC Whithey big black case package. I estimate everthing was a few hundred bucks as I didn't buy it.

It comes with an OBD reader with adapters, a digital multimeter with built-in tachometer & dwell, O2 sensor meter, several testing clips and a code disc for the other cars.
I don't know if the newer Volvos FWD's will use this thing or not?

My neighbor bought it out of the blue one day! I ended up helping him use it on his older American cars and a newer diesel Ford truck that he just had to have!
I don't know if that truck was even on OBD charts at the time. Maybe it was for his Ford Explorer that worried him. We used it on his '86 Oldsmobile the most. Throttle body injection issues!

When my neighbor passed away he made sure I inherited it. The O2 reader is about all I can use out of it with the Volvos. I do have relatives and friends to "experiment on" with it though! (:-)

I profess, I do just get by, with some decent results.
I don't hide much but I do watch, listen and learn!

Phil