1JZ Single Turbo Swap - O2 Sensor 2-Bolt Flange Fabrication from Old Turbo Oil Feed

Exhaustadvanced✓ OP Confirmed

Problem

After a 1JZ single turbo swap in an MKIII Supra with a stock auto ECU, the stock 2-bolt O2 sensor had no mounting point on the new turbo/downpipe setup. The owner needed the front O2 sensor connected for the stock ECU to run properly but lacked a compatible flange.

No mounting location for stock 2-bolt O2 sensor on single turbo setupStock ECU requires at minimum the first O2 sensor to function correctly

Root Cause

The aftermarket single turbo downpipe did not have a 2-bolt flange provision for the stock JZZ30 O2 sensor, which is required by the stock auto ECU for proper fuel management.

Confidence

Low confidence — Original poster confirmed this resolved the issue

View Original Thread →Posted November 2025 on SupraForums.com