LFX E39 no 02 sensor heat or out put

[V8R]

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 as well. Thanks for any thoughts.

[376FD]

I would check battery voltage at the pink/black wire with the sensor plugged in and key on. The heater shouldn't have anything to do with the ecu unless you have the ecu turning on the relay. The car I'm currently working on would run extremely lean and pull a LOT of timing (-10 degrees at idle) with the e39 ecu, I swapped to a e39a to match the engine and it instantly idled and ran better, timing was normal and it ran much smoother. My car is having other issues but the idle and o2 sensors all are normal.

Do you have a log?

[V8R]

Sorry. No log. The E39a doesn't support VSS from what I understand. I have battery voltage (12.8) at the pink/black wire with the key on. If I have the sensor plugged in but not installed in the exhaust manifold and I ground it to the block shouldn't it heat up? I get nothing.

[376FD]

Correct, the E39a uses a can signal for VSS so it reads 158mph at all times, but even with that the issue the e39a ran better than the e39. There may be tables that we don't get to see or play with that are coming into effect here.

You need to back probe the power wire while the O2 sensor is plugged in, it won't need to be grounded to the block, it should just heat up. If you have a partially severed wire you will get good voltage until you put a load on it. My guess is you'll see voltage drop as soon as the heater attempts to turn on.

[376FD]

Have you thought that maybe the engine is just running lean and your o2 sensors are working normally? Can you get the O2 sensors to read by revving?