Watching the computer it keeps going from Rich - Center - Lean - Center - Rich (upstream o2 reading). I watched it hit rich 23 times in one minute. The engine never changed rpm or showed any effect.

Is this normal or is it changing too much? This is at idle at about 684 rpm. Can't watch computer and count while driving, so I don't know if it does the same thing driving.

 

That's what the o2 sensor is supposed to do, constantly read and re-adjust (or send the data to the PCM to adjust) the air to fuel ratio to keep it as close to 14.7 to 1 as possible.

The more times it swings across center per minute, the better your fuel economy will be.

 

OK great. Since it did not effect the way it runs, I was hoping it was all good. I was not aware that it would swing so much. Maybe sometimes, more data is too much. I tend to look for problems even though none are apparent.

Decided to check things out after I replaced radiator today as I was installing new stereo and speakers, and just noticed the rapid changes.

Think I'll take it on a road trip to see grandkids tomorrow in Gainesville, and then to Arlington on Monday if all goes well.

Thanks.

 

Yup, that is normal closed loop operation. It is constantly making adjustments to try to maintain the ideal air/fuel ratio. When you go open loop (like full throttle for example), you would see something completely different (pegs out on a specific rich or lean air/fuel ratio as determined mainly by preset programming from the PCM).