2.5L ('98-'01) 1998 ranger 2.5 open loop

[uksparky]

California ranger 2.5 bought this truck with an engine problem, rebuilt it and got it running again got check engine light PO1131.... hooked up scanner and it stays in open loop lean condition ..but no vac leaks.. MAF is ok.. fuses ok... i replaced the 02s and front pipe/2 cats as the cat front was gutted ... so i unplugged the multi pin connector under the hood cleaned the pins and sprayed with electrical cleaner, restarted and let it warm up it went into closed loop for a few minutes in that time 0 voltage from 02 .. then back to open loop....checked voltage 12volts to the 02s... leaning towards a problem the ecu.. took it apart no bad solder connections

 

[uksparky]

only getting .032 volts between 02 connector and ecu for the 02 ground... pulled the ECU plug connector and found the red white wire .. no breaks in wire between 02 and ECU...... looks like the UCU is my fault

 

[uksparky]

all sorted after hours of going wrong way turn out one of the new 02s were defective

 

[RonD]

O2 12(downstream) is still low, should be in the 0.7-0.8v range and steady

O2 11(upstream) should be jumping around alot and between 0.3-0.5v area

But early days until Computer re-learns LTFT........... and those readings were at idle so won't be very accurate
Need some steady driving at 30-60mph speeds to get O2s working like they should