my 82 280zx L28 is running rich right now, just looking for some ideas on what it could be. only 60k miles on engine, original intake system and exhaust.

would appreciate the help.

 

SEARCHING always helps. Lots of info if you look for it.

Check:
-CHTS
-AFM
-TPS
-Timing
-Spark Plugs
-Cap & rotor
-Vacuum hoses

When and how did it start running rich?

 

i think itsbeen running rich for a while because my gas milage been not so good during city driving. and itested my o2 sensor and it was reading 800mv at 2500 rpm

 

^^^ Oh yeah... and check the O2 sensor.

 

i tested my o2 and its working.

 

What about all the other items? Have they been checked yet?

 

Are you sure the O2 sensor is working? Just because you got a reading from it doesn't mean it's working. If anything the reading should be bouncing around at 2500rpm. A still or consistent reading usually indicates a fouled out or dead O2 sensor. Or an O2 sensor that got rattled around too much, because you left it in the downpipe while you went to stores looking for replacement studs...

A way to check is that little green LED on the bottom of the ECU, once the car is warmed up and at operating temperature you rev the car a few times, then let it sit at idle and see if the LED blinks 5 or more times within a 10 second period.