New LS1 Owners - Newbie Tech - help me troubleshoot driver's side running rich

ok,straight to details, 99 ls1 swaped 240sx running on speed density tune,also running only on the 2 fronts o2 sensors,edelbrock fuel rails with a aeromotive fpr,(pic attached for reference), frost tune for all of that, car is been running for at least 2 years now, never had this problem.

Car is bogging and sometimes backfires,and its really low on power,it all started all of a sudden,also when i removed the spark plugs only the the driver side bank(1,3,5,7) where super rich(more like completely black) ,passenger side plug's (2,4,6,8)looked normal,i've checked voltage on the fuel pump,voltage on the coils,and did a visually inspection on the o2 sensor on the driver side bank.....any other ideas?



http://i172.photobucket.com/albums/w13/quezokete/IMG01267-20110723-1650.jpg

the return is at the bottom of the regulator, the feed will be running to the 2,4,6,8 injector bank first, then tru the crossover to a dead end at the back of the 1,3,5,7 bank


thanks in advance

You read any codes? I don't know if you swapped the car or not, but the previous owner may have pulled the bulb for your check engine light like the previous owner did for my LS1 swapped rx7.

i'm having the same problem with my LS1 swap. driver side running rich & all the plugs have a dry black carbon on them. runs good in park but once i drive it down the block it starts to miss & sputter. i disconnected my O2 sensors & it runs much better. my tuner seems to think i have a bad O2 sensor. i'm just waiting on a scan tool to confirm.

If it's running THAT rich, there should definately be some codes set. Like BANK1 STFT rich, P0300, etc. First thing I would do is find a scan tool that will not only read both current and history codes, but can also monitor live data. That being said, my first reaction is to think that your B1 02 sensor is giving the PCM an incorrect lean reading, causing the PCM to add fuel to B1. At any rate, you gotta have a scan tool to diag. Good luck. Cool swap.

Is your guage mounted on the return line? May wanna move it to the inlet on the rail so you can monitor pressure at the rail.

have 2000 T/A ls1 same problem exact same problem. my car puts codes out p0131 and p0405 i can erase the p0131 code no problem but the p0405 code comes right back after erasing without the car started the p0405 is an egr code low voltage the p0131 code is o2 sensor bank 1 this all started when i left the car sit for 2 years when i bought the car the lot said they upgraded the comp to a 2002 version by removing something maybe smog pump or something i think my comp needs reset now