why is bank 2 running so rich, double bamk 1?
 

i have changed O2 sensors, plugs pvc valve,intake gaskets, 1 injctor that was bad, and bank 2 is running 2 times as rich as bank one right from idle and never goes back down

helloo , i have the same problem , bank2 ( passenger ) is too rich around 0,9volt , where bank One still at 0,45 volt...
any ideas?
best regards

did you plug your O2sensors backwards?

hello ,
i have swap O2 sensor ( pre cat ) from bank 1 to 2 , and the problem stay on the same bank.
02 sensor backwards , you mean after cat ? ( i m french .. so my English is not so good )
after cat can have this effect?

thank's

tangi,

I may be able to answer your question, but I need some more information. First, what year is your Z? Second, what are you using to read the O2 sensor voltages?

hello, thanh's
it's an 2007 HR model
i read o2 voltage with torque pro , but my ecu tuner have read the same values...

Thanks. Here's my explanation. For 2003 and early 2004, the 350Z used narrow-band air-fuel sensors in the pre-cat position. The output voltages of these sensors would swing between approximately 0.2 volts and 0.9 volts, and the parameter output you could read on a scan tool was scaled between 0 and 1.25 volts per the OBD II specification. In mid-2004 Nissan changed to wide-band air-fuel sensors. These sensors can have outputs up to 2.5 volts, so the OBD II specification defined a new parameter output for them. At the perfect air-fuel ratio the sensors output 1.5 volts. Nissan, however, continued to use the older parameter to output these voltages, and had to scale the actual voltages to fit the 0 - 1.25 volt range. To differentiate the two banks, bank 2 was scaled to a value twice bank 1.

ok ! thank's , so it's normal !?
most of the time, here , nobody knows that !

best regards

Glad to help.