Help interpreting data
I went to the DIY section and consulted my PM CD reagrding testing air/fuel mixture with a multimeter. I got results that aren't what I expected.

With the O2 sensor disconnected, it started out at 6.5V and the temp indicator on the instrument panel indicated typical operating temperature. After idling for several minutes, I noticed that the ranges were increasing so I unplugged the sensor again and the voltage had risen to 6.92V. The PM cd says it should measure 2.1-4.8V.

With the sensor connected, the voltage did oscillate. The range was +1.3V to +1.7V from the 6.92V baseline with the sensor disconnected.

I also noticed when I removed the air filter lid that the "choke plate" (?) was closed when the car was not running. Is that normal? On all my domestic vehicles, I believe the resting position was open.

Thanks again for the help.

Darrell

I don't know what kind of car you have
 

but unless it is real old that isn't a "choke plate" and yes, it should be shut with the engine off.
Jim
'85 300D
'95 E320
'97 CRV

The car is a 1987 190E 2.3 8 valve.