P0171 troubleshot, now P0133, P0130, P0153, P0150

[2000WA100]

I originally had P0171 system too lean CEL and did the following -

Cleaned up the MAF (dirty)
Checked fuel trims on techstream and found long term high on banks 1&2 at idle(+~30), dropping as RPMs increased
Pulled air intake manifold and cleaned throttle body(dirty), replaced air filter, checked/cleaned/tightened connections
Disconnected battery for 30 minutes to reset memory
Drove ~140 highway miles with no issues
Last few miles of street driving CEL comes back, now with P0133, P0130, P0153, P0150 in addition to P0171

P0133/P0153 are slow response for HO2S which I assume is simply a precursor to P0130/P0150 Heated Oxygen Sensor Circuit Malfunction (Sensor 1 for banks 1&2)

I've seen posts about gas caps, but not sure what to look for, there is no pressure or vacuum(that I hear or feel) when I unscrew mine.

I thought the voltages for the HO2S' were tracking, but I could be wrong.

Next step- Back on techstream and see if fuel trims have changed at all, check HO2S' voltage (previously I saw fluctuating from .1 to .9 V which I believe is correct, right?)



Other info - No performance issues that I can tell, idle at 700 RPM. Both banks being high made me think vacuum leak (I have smoke test scheduled). Now both sensors "malfunction" still points towards common issue IMO. If I still see high FTs I'm still assuming vacuum leak and proceeding with smoke test.

 

[2000WA100]

So far what I'm seeing in techstream at different RPMs

 

[2000WA100]

So P0133, P0130, P0153, P0150 came in due to a hose popping off the air intake manifold. It didn't have a clip on it so I put a hose clamp on there. Smoke test turned up a small leak which was corrected.

Fuel trims now look real good under load, but are over +30 at idle.

So MAF cleaned, throttle body cleaned, vacuum leaks corrected, ECM reset and problem remains at idle. I think injectors are the next stop?

 

[2000WA100]

So I ended up taking it in to a dealer. They found a leak on the intake manifold gasket, 17171-50020, which was tough to find. I tried to have them show me the leak and they had a difficult time demonstrating with the carbon cleaner, but assured me they had found it while the engine was hot after driving it around for troubleshooting. So I took their word for it and had them replace both sides and do the starter while they were in there. Trims look pretty good now, one bank is a touch high (+5) at idle, but I'm not going to go after it at this point, tired of looking at trims honestly. All signs pointed to an air leak and it was an air leak, so I guess the lesson learned is keep looking until you find it lol.