attached is the data log from the most recent testing on my 7727 ecm equipped, TPI based small block mopar. I'm baffled. according to the sensor data, I'm running dead lean. according to plug reading and my nose, its incredibly rich. plugs are black and sooty after just a little run time, hard to start without opening the throttle considerably, and rich enough to make my eyes water.

I have no dead cylenders, and no observed leaks upstream of the oxygen sensor (heated 4 wire, bosch, located in drivers side long tube header collector.

so what am I missing? is it tuning, or mechanical? what should I check next?

I'm running axcn $8d

 

the other baffling thing that may play into this, is that to get tunerpro to talk to the ecm, I had to use the 10k resister. from what ive been reading, this should not have to be used. I'm also getting lots of connection errors blinking during the datalogging.

 

Your O2 is reading false and causing the car to BELIEVE it's lean and continue to add more fuel causing it to run rich in reality. Fix your O2 or check again for leaks.

 

Ive seen this happen before, an overly rich mixture resulting in un-burned fuel can read as lean.

 

finally had a chance to check the datalogs tonight. either 450.8MV or 0. nothing in between. and over half the open loop time was at 0.

so I guess its time to dig deeper. I'm thinking bad ground or sensor. but its grounded to the same bolt that the rest of the ECM wires are grounded to, and the heater works, which also shares the ground bolt. so maybe bad signal wire? or bad sensor. but definitely a contained sensor problem. I think. right? maybe?