Fuel trims and hesitation after new cats?

So the hesitation seems like it would be from the system trying to lean the fuel mixture out from the rich reading of 9.3, (both STFT and LTFT are based almost entirely on the upstream (Sensor 1) AFR sensors.)

Code P2A03 - O2 Sensor Circuit Range/Performance (Bank 2, Sensor 1)

So this will be a sensor issue sensor 1 bank 2 or you have a leaking/bad fuel injector, I would remove the spark plugs to see which one is dark or black in color, this will be the cylinder having the issue, also since the spark plug is out I would do a compression test on the cylinder as well. Please go over these guides to help as well

https://www.2carpros.com/articles/why-an-automotive-engine-will-run-rich

and

https://www.2carpros.com/articles/how-to-test-engine-compression

Please upload a short video in your response of the problem, so I can see what's going on :)

Ken,

Thank you for the prompt reply. I have not had the time to pull the plugs yet, however, I was watching some more live data and now the STFT for B1 and B2 hover around +5 at idle, fluctuating from anywhere between -10 and +15. LTFT B1 is now +4.x and B2 is +11.x. A/F Alpha B1/B2 ranges from 97% - 120% and both downstream sensors are a constant 0.28V (HO2S2 MNTR B1/B2 = LEAN with no change). The car runs fine, other than the aforementioned hesitation and I don't hear an exhaust leak, plus, there are no DTCs present. I'll check for vacuum leaks in the intake system this weekend.

So that we're on the same page, the car is my daily but doesn't get driven very far as I work from home. I've had it 6 years and have put 20k mi on it. It has Stillen long tube cold air intakes that put the filters in front to the radiator, Concept Z Performance PCV delete kit, throttle bodies from a 2017 QX50, deleted throttle body coolant lines, new upper plenum gasket, valve cover gaskets, spark plugs, spark plug tube seals and, as mentioned in my original post, B2S1 A/F sensor, high flow cats and cat-back. All the work has been done by me within the last 10k mi.

That fact that bank 2 is at +11 is tell us you have one or more fuel injectors and can be leaking or there is an exhaust leak on bank 2 which will fool the computer into thinking the bank is lean and it will richen up the fuel mixture. I would remove the spark plugs on bank two to see if one or all are dark compared to bank 1. If you find one that is dark you found the problem cylinder. Please do the compression test as well as long as the spark plugs or removed. This is so we don't chase our tail when the engine is having a problem, (low compression). Let me know what you find.

I removed the plugs on bank 2, but they look fine to me (see images). I tried doing a compression test, but the kit I have is the thread type and it doesn't fit down into the spark plug tube. Apparently, I need some sort of adapter rod with a rubber tip that goes into the tube. I don't see how that would hold the pressure if it doesn't screw in. I forgot to mention that I've also replaced the fuel damper assembly a while back due to it leaking (this car actually uses 3 of them. 1 before the rail and 1 on each bank's rail directly above the injectors. I replaced the one before the rail.)

I don't know why it's not loading the images. It shows them before I hit the reply button.

I downsized them, we'll see if that makes s difference.

Yes, it is a display issue, they are working on it and they will show up in the next few days. The videos still work if you want to do a short video and upload it here as well.

I just made a short video clip of the images of the plugs.

Nice, thank you for the video, so the last spark plug looks lean, no or little fuel this will be he cylinder having the issue. This is why the system is trying to richen the mixture, if the compression is good I would replace the fuel injector on that cylinder. Clear the codes and see what happens.

Is that because the tip isn't brown like the other 2? Do you know what adapter I need to do the compression test?

Yes, do you see how the others are darker? This means they are burning fuel. This video will show you how and what adapter you need.

https://www.youtube.com/watch?v=KOxIm1F8AW0

I have a similar kit as in the video, but the FSM says I need one of these

I figured it out. Compression numbers on C2, C4 and C6 were all between 240 - 245 psi. The last plug in the video was C6. I should just replace the injector then? The book says the only way to test the injectors, other than listening for an energized click, is to pull them out, put them in a container, still connected to the rail, and fire them to make sure they all flow the same.

Btw, LTFT B2 is now +16.

Yep, that is a good way to compare the spray pattern, but it looks like from this LTFT B2 reading the injector is clogged, here is a guide that can help you test the injector as well.

https://www.2carpros.com/articles/how-to-test-a-fuel-injector

Please go over this guide and get back to us.

Ken,

My apologies for the delayed response. Holidays, family, etc. I do hear a click from each injector with the engine running. Connecting a test light to battery neg and probing the injector wires causes the test light to light up on all 3 injectors on bank 2. When probed, each injector fired every time the light turned on with what little pressure remained in the line. I was unable to do the PCM pulse test since the upper plenum has to be removed to access the injectors. C2 and C4 showed 13.2 ohms and C6 showed 12.9 ohms. I've included a photo of each port, taken after probing. I did not have time to remove the injectors, but I noticed the drive side valve cover gasket is leaking so I will be taking it apart again very soon to replace the gasket (it's the same steps to get to the injectors).

I did get under the car with it idling to see if I could find an exhaust leak, but I could not see, hear or smell one.

Also, the P2A03 code has come back.

In case the photos don't load.

Okay, yep, those intake ports look okay, and the Ohm reading are good but that is only one test for the injector, you can have a clogged nozzle which will lean the cylinder out which is what you are fighting. I would remove the injector and test it as in the guide.

An update to this:
I never got around to removing the injectors, I've been focusing on my Tahoe, which you've actually been helping me with also, and this car has just been sitting.

I installed an oil pressure sensor and gauge to this car and was under it while running, making sure there were no leaks and I could smell exhaust. So, I used a shop vac to pump air into the tail pipe and sprayed the exhaust joints with soapy water. The gasket between the manifold and cat on bank 2 was leaking in 3 different spots, bank 1 was leaking in 1 spot and both rear o2 sensors were leaking. I never went back and re-torqued the bolts after driving it for a bit once I installed the cats and cat back exhaust so I tightened everything up.

This actually made the P2A03 code go away and it drove fine, for a day. Now, for whatever reason, my fuel trims on both banks are super high and the rear o2 sensors are reading lean. The video is about 15 second of idle at a light with the AC on and another 15 seconds of driving showing these values. I've checked for intake leaks (I have aftermarket aluminum cold air intakes and I deleted my PCV valves years ago, all ports are capped with vacuum plugs) and I've looked over the exhaust again, but I can't find anything.

I was/am having an issue with a P0447 evap can vent control valve returning incorrect voltage to ECM, but I checked the voltage to the valve, it's battery voltage, I checked continuity between the valve and the ECM, it exists, the hose is not clogged, I can blow through the valve when it's not energized and it seals off when it is. I erased the code to see if it will come back so, there are currently no codes. I did notice when I tested the wrong wire in the valve connector at first that the wire going to the ECM from the valve showed 3 volts when put to ground. Is that a reference voltage or is that a problem?

I have no idea why both trims are so high now.

Hmm, I think the valve is suppose to be shut/closed when the valve is removed and then open when energized is this what you mean?

The FSM says the valve is typically open and it closes when 12V is applied across the terminals

Yep that is my bad I was thinking of the purge valve, not the canister valve. So that is normal. The purge valve up by the engine is the one you are talking about correct?

Vent valve near tank/canister = lets the EVAP system breathe or seals it for testing.
Purge valve near engine = meters fuel vapors into the engine.

Also, I was re-reading the post and the way you are testing for a vacuum leak may not work, also, we need to get a visual on the injector spray pattern of the cylinder with the white spark plug. Please go over this video for the vacuum leak check.

https://www.youtube.com/watch?v=LRKWV4Are5c

You have many after market parts on this car which can cause issues as well FYI.

No, sir. I am talking about the canister vent control valve, not the purge valve. The code is P0447 incorrect return voltage to ECM from vent control valve.

If you are referring to my use of the shop vac, I wasn't checking for vacuum leaks, I was checking for pressure leaks in the exhaust by moving the hose of the shop vac to the output side, putting the hose in the tail pipe, blocking the other pipe with a rag and "pressurizing" the exhaust, then spraying the joints with soapy water. Retightening the bolts from the manifold to the cat on bank 2 made the P2A03 code go away. The only code showing now is the P0447, even though both rear oxygen sensors are reading lean constantly and the fuel trims are high now.

I've done what was shown in the video. I sprayed every inch of the upper and lower plenum, intake tubes, capped off PCV ports, throttle bodies and MAF sensor locations. No vacuum leaks found.

I've had many aftermarket parts on the car for the past 6 years with no related issues.

Okay, nice work, I would go back to testing the fuel injector spray pattern.

If the computer is compensating, for whatever issue is happening, to keep the front AFSs in the middle, why would both rear o2 sensors be reading lean?

I meant rich. High voltage is low oxygen, right?

Not really, anytime there is a misfire the system will be lean. There is more air than exhaust gasses when misfires occur. Please go over this guide which explains is better.

https://www.2carpros.com/articles/engine-misfires-or-runs-rough/

Please go over this guide and get back to me.

But I'm not getting a misfire. My scan tool shows real time misfire counts and they're all 0.

So it idles rough with no misfire, that brings us back to a poor mixture, do you ever check the fuel injector spray pattern?

No sir, it does not idle rough. It does not misfire. There is no vacuum leak that I could find. I fixed the small exhaust leaks I did find. The issues are very high fuel trims (I reset the long term learned values and within a few drive cycles, bank 2 LTFT is at +20) and both rear oxygen sensors reading constant high voltages. I'm working on checking the injector spray patterns.