I have a 727 ecm 1990, I have changed ignition curve on the the chip and installed an adjustable fp regulator and pressure is set at 53 psi with no vac. Here is the problem: After car is warmed up when I cruise at part throttle 1400 rpm for the 50 sec the ecm looks for to set a fault I get the check engine light and code 45 is set.
I have recorded data using datamaster and at the point the o2 sensor flat lines for a long time here is what I have for data: o2 volts around 850, blm/int 128, spark adv 34.5.
What needs to be done to correct the fault? I have never messed with the VE values but looking at the data it appears to be O.K. I have replaced the o2 sensor, opened the air cleaner lid, and bypassed the throttle body water.
Anyone else have this problem? Any suggestions? What else do I need to look at? This problem seems to consistently happen at the same place on the road everyday as I drive back and forth to work so I believe I can rule out electrical problem.
Any help is greatly appreciated! This forum is great for new chip burners like myself.

 

If you could post the log in the datamaster format and in a CSV format we might be able to look at it and see what is going on.

 

Not sure I did this right, but I attached the file from datamaster.

 

Well I can't get the file to go, looks like the file type is not accepted by this forum?
I noticed you are building a 406, I have one done with the vortec heads and am trying to decide what FI system to use. Any suggestions?