My gauge runs on rich most of the time or lean. At part throttle it runs either on really rich or really lean. Full throttle it stays at the same point. At idle it is supposed to run back and forth right? Mine is not doing this, why? I have a JDM b16a1 in an 89 Civic Si HB with a PR3 computer. Everything is basically stock for now except the air intake.

 

I don't think that the gueage is wrong, I think there is something wrong with the motor. If you jsut bought the gauge then exchange it for another one. If it is not new, go buy a new one, try it out to see what it reads, then return that one if the reading are different.

 

It could be a dead or dying oxygen sensor. When they get old, the response is slow and the voltage low. Also, if the sensor is mounted too far downstream it will never heat up to operating temp and always output erroneous information.

 

This sounds like a carbon-copy of how my engine runs. It's normal.