First mandatory action is to secure an appointment with the chiropractor. You will need it after contortioning/probing/reaching/following/inserting very fine probes at the O2 sensor plugs ending at the ECU to confirm the presence of a valid varying signal there. If absent, go back to next and next and next connector probing to see if at some joint the signal gets valid. (engine running). Piercing the cable may be the only way to probe at certain points. And shaking/bending the wiring while probing is never a bad idea.
It is the ****s but it is been like 30 years since they stopped making automobiles. They are now computers with wheels, and you need electronics skills to deal with instead of mechanical knowledge.

 

Thanks all for the input. I ordered some alligator clips and T-pins so I can better probe and backprobe the connectors per the video on Sandman's forum. I don't have great hope that it's a loose pin because I didn't notice any real change in the reading when I was handling the connector wires, but I will test again. What's weird is that the voltage reading when I first took to the forum was pretty much a constant .45 volts, with very very slight variation. Now, the voltage consistently starts out around .45 volts and over the course of the first few minutes of driving, it drops to 0.00 volts for that sensor. However, it is obviously running very rich, as it is guzzling fuel, and there is a coating of soot around the end of the exhaust pipe, in addition to the smell. Now I'm just confused because it seems like it should either be working or have a flatline reading if it were a wiring issue, but it just drops from .45 to 0.00 and then stays there. The codes I am now getting that I can remember are P0154, P0150, P1174, P0174, P1412 (last one is because I removed the SAI tubes on the driver side and capped the holes in the block - any chance capping the SAI on just one side of the engine would cause this whole issue on the opposite side?).

 

Okay, the problem you are seeing in the classic plugged fuel injector on one of the cylinders on that side. It causes the entire side to read lean and the ECU compensates bye pouring more fuel into the remaining three cylinders but it can't make up for the fact that one cylinder isn't getting enough fuel.

 

Extinct, what you're describing makes a lot of sense to me based on the symptoms. Is that something that can be "unplugged" or should I replace the fuel injector(s)? I suspect the #8 cylinder - I pulled the spark plug today and it was really grimy, including looking like oil had leaked down onto the boot and plug and into the threads. Don't know if that would be a cause or effect of the plugged injector.

Jessie

 

Start by swapping plugs left to right. See if anything changes. Then swap plug wires left to right, see if anything changes. Then swap injectors left to right, see if anything changes. It will be tempting to throw parts at it because people will say do it while you are in there, but members have gotten bad injectors new before and doing those three swaps first will allow us to definitively determine the problem, so when we put a new part in if it is bad we know that too.

 

Will do, and will report back @Extinct . Thanks!