For while I was having P1174 and P1171 codes as well as some related to EVAP. I replaced the purge valve, and the evap codes are gone. I drove quite a bit and past the time it takes for these to normally reappear. Now the only code I get is P1174 which means that Bank 2 is lean.

My idle is a little rough, and when I engage into gear (especially reverse) the engine idle falls, and the engine sounds like it is going to die. After a second or so it goes back up, but sometimes the engine dies completely. I do have an exhaust leak on the other side Bank 1. Would this affect it?

I was also getting pending misfire codes for 3 bank 1 cylinders, but have not got them recently. I replaced the injector O rings, as well as the upper manifold gasket. It didn't seem to change anything.

I was having some issues with oxygen sensors. The new bank 1 walker oxygen sensor has failed, and is now replaced with the old (working) bosch sensor. Could the difference in sensors be causing the lean code? I still had the dying in reverse issue when both sensors were newly installed.

 

Vacuum leak

 

Exhaust leaked on side one won't affect anything and neither will having the bad sensor on that side. If it only throws the code while idling it likely is a vacuum leak if it will throw it going down the highway could be a bad mass airflow

 

Since the lean code is only on one side does that mean that the intake manifold gasket(s)/injector o rings are bad, or could it be something else?

 

I would probably suspect injector o-rains or perhaps intake manifold gasket since it's only on one side

 

The injector o rings and upper intake manifold gasket has been replaced, but its possible the o rings were of bad quality since they were cheap (but recommended on this forum). The lower intake manifold gasket is decently new since the engine was rebuilt, but its possible it didn't seat properly.

 

Check the intake bolts for tightness, also possible you tore/cut an o-ring on install. Did you put any grease on the o-rings during install?

 

I put some engine oil on the o rings, but they did seem to be looser than the o rings that were on before.

 

Kinda doubt that is it then. Put a wrench on the intake bolts.

 

Now the P1171 code is back. Does this mean I have a vacuum leak on both sides, but it is worse on bank 2?