my right bank is running VERY lean..... the car when first started, runs lean on both sides, but after about 30 sec's, the left bank appears to be fine, but the right bank is reading .1 which is exceptionally lean.... I checked my fuel preasure which is fine. I can't find any vaccum leaks..... I'm just praying it's not an O2.... any other ideas or is it an O2? (the car running sound exceptionally poor since this started happening. I checked the program and everything is configured correctly.... I have 36# lucas injectors as well as a walbro 255 pump. the pump was installed a few weeks ago..... Any ideas?

 

TTT any ideas?

 

Describe the EXACT behaviour of your O2 readings. At cold start, it is completely normal for the sensors to read 450mV (the voltage applied by the PCM), and then drop slowly to 0xx mV's as they warm up. After bottoming out, the PCM will go into closed loop, and they should start cycling in the range of 1xx - 8xx mVs.

It sounds like your right side sensor is not heating up all the way. Is the PCM going into closed loop?

 

at cold start, the drivers side A/F gauge reads mild to lean for about 30 sec's then drops down to lean...... the voltages on on both my O2's by free scan is around .4 or .5 ..... then after the 30 seconds, I can give it some gas, and the drivers side will fluxuate to where it should be (bn .7 and .9 bouncing all over the place... have in mind the car is still cold) but the passanger side will stay at about .1 ..... doesn't matter how much gas I give it, it says that.... if I let off the gas, then the drivers side will drop to dangerously low also..

 

The O2 values shouldn't start to fluctuate until the PCM goes into closed loop. In order to do that, 1) O2 sensors must be hot and working, 2) coolant must mean minimum value.... ranges from 120-140degF, and 3) a timer has to time out... seems to be at least 2 minutes.

When the O2 sensors start to "fluctuate", they should not stay on the rich side (700-900mVs). They should cover the full range of at least 100mV to 900mV.

You either have a dead sensor on one side, or the wiring harness extensions are bad, or the sensors simply aren't getting hot enough.

It is normal for the sensors to show "lean" when you let the throttle close above 1,300rpm or so.... the PCM cuts fuel until the RPM drops down below that level.

What you describe as happening doesn't sound correct for either side.

 

I replaced both O2's.... still does it...Although I did notice that when I opened the gas cap I didn't hear it decompress like it normally does... I'm woundering if I have some sort of vaccum leak in my fuel system