P0130 + bank 1 misfires

Maximumwarp

Well-known member
Mar 22, 2015
820
19
Fairburn GA
'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.
 

Maximumwarp

Well-known member
Mar 22, 2015
820
19
Fairburn GA
So this is still going on. I pulled the upper intake again and replaced the upper-to-lower gasket on a hunch. Now all I'm getting is cylinder 1 misfires and the general misfire code (0300 and 0301). Flashing CEL under acceleration with those codes. I hate to just throw parts at a problem, but I went ahead and replaced the plugs and wires since the existing set was probably three years old. NGK 5553 plugs and Kingsborne 8mm wires, before and after. Plugs didn't look terrible when I pulled them, and cylinder 1's plug didn't look different than any of the others.

0301 and 0300 came right back. Am I looking at coils next? When a coil fails, could it fail for just one cylinder or would it fail for all four that it powers?
 

Maximumwarp

Well-known member
Mar 22, 2015
820
19
Fairburn GA
Coil would take out 2 cylinders at a time normally.

Where should I be looking next? Injector o-rings? I sprayed some starting fluid under the manifold through that gap on the passenger side front with the engine running to check for more leaks and the RPM dipped.
 
Aug 20, 2007
2,693
30
Nashville TN
you'll have to take the manifold off to replace the coils, so I would just replace the injector o rings and the coils and any other top end gasket while it's all off. tighten everything town to spec, and also check all your intake hose connections
 

discostew

Well-known member
Sep 14, 2010
6,417
497
Northern Illinois
I would look at the harness to that o2 sensor. Maybe take a good look at the harness for the injectors down that bank with misfires.
Sometimes I just backprobe the o2 sensor signal with a meter. I don’t trust a lot of scanners to be fast enough to catch stuff.
Also if you do check the circuit with a meter. Get a good reading on that red/black wire. It should be a ground from the ECM. If the sensor gets fixed at 450mv (or whatever the reference voltage is for that circuit) then ground that red and black wire and see if you have activity with it grounded.
These Bosch trucks do some weird shit with the o2 sensor circuits. They aren’t happy with just waiting for an o2 sensor to get hot enough to start working. They actually turn them off by opening that ground. I’ve seen lots of those drivers in the ECM fail and I just ground that wire to the bracket the ECM is mounted on. The truck doesn’t seem to care where the ground comes from and I’ve seen none of those trucks back for the same shit after I do that.