'99 D2. I've been chasing some emissions/O2-related codes for a while now. Earlier in the year it was throwing various O2 codes at me. I replaced the front sensors, but the codes returned (P0171 and 174, lean on banks 1 and 2), so I gave up and took it to Bear Valley because I needed to get the thing through an emissions check ASAP. They found that the O2's I had installed weren't switching, so they replaced them again and they started working. They also noted a failed MAF, so I took it home and installed a new OE Bosch MAF. I'm also pretty sure I replaced the spark plugs at this time, just for good measure. Codes stayed gone for a while, then I started getting the same bank 1 and 2 lean codes again. This time I did what I should have done in the first place and skeeted some starting fluid around all the fittings looking for a vacuum leak. Lo and behold, I found a leak at the brake booster hose fitting on the side of the intake plenum. I replaced the fitting and now the lean codes are gone, but in their place I have a P0130 code (Bank 1, Sensor 1 malfunction) along with misfires on all of bank 1.
Would the lean codes have been hiding an issue with B1S1, or perhaps would running lean for a few months have caused it to fail? I did pull the upper intake plenum to replace the brake booster hose fitting, but I've re-checked all my connections and it doesn't appear that I did anything to cause the misfires/P0130 to appear when I re-installed the intake. Would running lean for so long throw the adaptive values out of whack enough to cause B1S1 to malfunction? I've tried the redneck method of resetting the adaptive values (disconnecting and then holding the battery terminals together for a couple of hours) but I think I've read that this doesn't work, and they need to be reset with a capable scan tool.
Would the lean codes have been hiding an issue with B1S1, or perhaps would running lean for a few months have caused it to fail? I did pull the upper intake plenum to replace the brake booster hose fitting, but I've re-checked all my connections and it doesn't appear that I did anything to cause the misfires/P0130 to appear when I re-installed the intake. Would running lean for so long throw the adaptive values out of whack enough to cause B1S1 to malfunction? I've tried the redneck method of resetting the adaptive values (disconnecting and then holding the battery terminals together for a couple of hours) but I think I've read that this doesn't work, and they need to be reset with a capable scan tool.