can anyone tell me why someone would remove the o2 sensor with stock ecu and a fuel cut defender? the previous owner did this and i really want to know what the reasoning could be. car is a 1987 turbo 2.

 

People do many dumb things...

 

Car communities have an acronym for this: DPO. Stands for Dumb Previous Owner.

There's no valid reason to disconnect the O2 sensor. Also watch that FCD. As long as you're not seeing more than about 8 PSI, you're fine. Any more and you need to address fuel as the engine will run lean on the stock ECU.

 

I put an o2 sensor back in yesterday, I am only seeing 6 psi, but the previous owner told me that it is a knightsport turbo upgrade (t3/t4 model according to him). from what i have been researching and reading, it is just an upgraded compressor housing, but i do not know. he did install a fuel pump from an FD, so do you think that i am fine to drive while i save for an ecu?

 

Assuming it's similar to the other Japanese hybrids (T04b V-trim), it's going to be able to flow about 25% more air the a stock turbo. At low boost, it will be manageable with a stock ECU & stock injectors. The AFM will measure airflow adequately. I would not suggest running any more boost until you have larger injectors, a wideband 02 sensor/gauge and/or an EGT gauge & programmable ECU (fuel and timing control). The FCD then ends up in the classifieds or the trash.

 

so would this be the o2 connector? i am terrible at reading wiring diagrams, but the PO had it grounded or connected to another connector. and what is the green wire (with black stripe) shown in the second picture? it that was should be connected to the thermostat housing instead of the o2 wire (assuming it is the o2)

 

Bump. I wanna know what wire is supposed to go to the thermostat housing so i can plug my o2 back in.