I have the plx setup and i tried running the pcm off of the narrowband signal of the wideband (supposed to be able to do this with plx) I was watching the cycle and it is reading about 200mv or so higher than bank 2 and is leaning out my fuel trims so bad i have to run in open loop. the guage also tells me its running lean. anybody else have this problem? i didn't want to drill another hole and run a stock sensor but i guess i have no choice.

 

what wire did you hook to on the stock harness?

 

purple one and it comes from the narrowband output from the plx box. it is consistantly 200-600mv higher than the other bank, but my guage is reading it as being lean cause of the fuel trims so that seems to be fine.

 

thats the one i hooked mine to. the plx does read more sensitive than the narrow band, but i just tuned the truck to the plx.

after installing the plx did you reset your fuel trims? maybe your getting a problem between the plx as a narrow band and your old fuel trims.

 

yes sir that is a weird problem. i just recently did the same install myself and mine simulates the narrowband very well. the stocker and the PLX do read a little different but not to the extent you're talking about. like previously mentioned, make sure you reset the fuel trims and disable the fuel trim learn in the VCM scanner.

Also, when you leave it in closed loop, how lean does it go? it seems to me like if you were getting an actual lean condition the fuel trims would go positive and sort it out at least a little bit.

 

it would go 20-1. it will not fix it self because it relies on the narrowband to do so. the narrowband is telling it is rich so the fuel trims are leaning it out, but it is not actually rich. the wb is correct in saying it is at around 14-15 in open loop but in cl it leans

 

i just drilled another hole and welded another bung for the stock sensor runs perfect now.