LFX E39 no 02 sensor activity
I'm hoping some of you really smart guys might point me in a direction that will help. Details,
2014 LFX conversion into 2002 Miata. Custom stand alone harness. Front 02 sensors only. E39 processor same base tune that has worked fine on other conversions. Starts and warms up fine. Wont go into closed loop due to no 02 activity. Scan tool shows sensors sitting on .015 volts. Very erratically it will jump up to .7 or .8 and engine will smooth right out. 2 different sets of sensor. 1 set new, 1 set used, known good from perfectly running car. 2 different pcm's with same base tune. I have pinned back both connectors to PCM and all wires have continuity and are where they are supposed to be. Eventually it will start throwing lean codes, misfire codes and 02 low circuit codes. When i use the scan tool to do the 5 step 02 tests they both pass all tests. If I pull sensors and ground them to the engine and turn on the key I get no heat at all. I have battery voltage at the pink and black wire at the sensor with key on.
I have stripped down the harness and checked for broken wires. Fuel pressure is 58 psi at the DI pump and anywhere from 600 to 1200 at the injector depending on rpm. Right angle elbow off throttle body. Maf is 7.5 inches from throttle body. I moved it back to 12 inches and it improved idle but didn't change anything else. I have had a helper wiggle connections and plugs but no consistent change for the better.
Pulling out what's left of my hair. Customer car and it should have been delivered ages ago. Checked basics. Compression. Leak down, etc. Engine has less that 5k miles. Any suggestions welcome. I'm going to post on HP Tuners and LS1 as well. Thanks for any thoughts.
