idling problem and running rich

[william_fh]

hi everyone i have a 89 240sx with a swapped rb25 that idles like crap. when it idles it fluctuates up and down between 400 to 1000 rpm and it gets worse and stalls out unless i rev it up to keep it alive. so i took it to work and diagnosed it. we found out that its running rich way to rich. im guessing the richness is making it idle like crap. so we check the oxygen sensor . and no voltage coming from the ecu pin 29 oxygen sensor where in the fsm it calls for .6v-1v(variant voltage). we check for continuity from the connector to the ecu and it was fine.(1.5ohms). so i dont know what it could be but we think it might be the computer itself(ECU). other then that it runs pretty good. any inputs will be appreciated.

thanks

[S13 240SX]

check mass air flow sensor to be at fault for running rich and check the iacv

[mott6904]

Check to make sure your tps is set right. On a rb20 the oxygen sensor has 3 wires 1 is the signal and the other are heater wires. The heater has 12 volts which is tapped into the main power supply to the sensors and the ground is switched by the ecu. I dont know if its different on a rb25. I would start off by checking you tps sensor is adjust right. Also check for a leak in your intake piping