Issue Dropping in to open loop?

So I have been getting my tune dialed in and on the way home from work today I was running a data log checking for KR and i look at my WBO2 and its running really rich, I looked at the scantool and for some reason it was in OL. I stepped in to the throttle and it went OL-Drive then right back to CL. I looked through the log and it looks like the bank 2 O2 stopped reading for a short period of time. could this be a bad O2? or is it an issue with my tune? there were no codes, and The O2 sensors were just replaced back in March and they probably have less than 5k miles on them. I attached the tune and log file.

Same issue again this morning twice on the way in to work still with no codes. as soon as it drops in to open loop it goes extremely rich, I seen 1.438 EQ today. forcing it in to OL-Drive a few times and it straightens back out for a little bit. I am going to replace the o2 again and see if that helps, maybe I got a bad sensor.

At part throttle (low throttle) your HO2S11 (bank1 sensor1) NBO2 shows steady high voltage... looks like you possibly have a leaky injector on bank1.


I see that your WB is on bank2, it follows the LTFT2 ramp up, it almost looks like there is a 7 second airleak on bank2 (is the exhaust header leaking...?).

VE table has a strange hump right where this LTFT2 ramp up occurs, looks like VE table is compensating for airleak.

Try this before replacing NB02: swap NBO2's across banks.


Also, try setting B4105 to 450 mV in all cells.

Also, your IAT is high, what is ambient air temperature in your location...?

Also, remove these pids to get pid channel count down to 24: GM.DYNCYLAIR_DMA, SAE.VSS.

I'll try the 02 swap as soon as I can, I will also check for an air leak, I don't really hear one. the IAT is high because of an issue routing the air intake, I am short on room and working on a new setup to attempt to lower IAT temps. The exhaust is a crossover to single type and the wbo2 is just after the merge.

So I swapped the NBO2's bank to bank on Sunday and also checked for leaks and found none upstream of the O2's. I have a slip fit cat and muffler with band clamps and if I plug off the tail pipe I can hear a small leak between the muffler and cat but thats more than 16" past the wbo2, would this cause any issues? I have been data logging drives to work and home since (30mins each way) and have not seen the same issue come back.

If air leak is sufficiently far from front NBO2 it should be ok (other than exhaust being sucked into cabin as you drive down the highway).

Post new logs.

The only time I could hear it while underneath is with it running and someone capping off the tailpipe for ~10-20 sec intervals forcing full backpressure. I hope to have my new air intake setup done this weekend to lower my IAT's. this may involve a retune as I plan to totally change the intake tube config. Hopefully it will lower my IAT's a lot. in the the log 102 attached the ambient temp was in the mid 40F range

So back to the O2 issue, up till this Friday I haven’t had any trouble with them. But since its getting close to winter I decided to remove my RR pcm and re flash the stock pcm and put it back in the vehicle, but unsure if there was an issue with that pcm due to the previous 02 issue, I also reflashed a spare 411 pcm that I have for another project and took it along with me because I was headed 1.5 hrs north for the weekend. I didn’t bring my efilive but I have a Bluetooth android dongle and an app that allows me to check codes and read basic parameters. I noticed after about 70 minutes while driving that my WB02 was reading a little rich on the gauge ~14:1 AFR so I plugged in my Bluetooth and I was getting no LTFT readings at all also no codes. Just for fun I hit the clear codes button and that’s when all hell broke loose. The fuel trim for B1S1 (it was B1S2 before the swap) went in to the 50’s and the WB02 gauge started reading ~8.5:1 AFR and also the transmission kicked out of TCC. I pulled off the next exit and thinking maybe there was actually a problem with the pcm because there were still no codes. I swapped it with the spare, and finished my drive and everything was fine. Saturday I drove all around up north with no issues. Sunday we left for home and ~60 minutes in to the drive the same thing happened. Extremely rich and kicking out of TCC and running horrible, I pulled off the highway and unplugged the B1S1 o2 sensor thinking that if it wasn’t reading anything I would get a check engine light and an open loop condition. Well that’s where I am totally confused. I didn’t get a code or a check engine light, I even stopped and restarted the engine a few times. So I thought well maybe if I disable the MAF I should definitely get a code and a check engine light. I pulled the yellow wire from the MAF and still no codes even after 4 restarts no codes. I tried just hitting clear codes while driving like that and the engine shut down completely for a split second. I never could get a code or check engine light and had to drive it the rest of the way home ~30 mins running at ~12:1 AFR. I got home and replaced the B1S1 O2 sensor and have not had an issue since. Could this be something to do with just long term highway driving, can a bad O2 sensor really make it run that rich? Why would I have not gotten any codes when unplugging the o2 and MAF? Why did the trans act up when running so rich?
Tune is attached but I had no way to log data, Sorry for the long winder

Your MAF DTC's are set to 2-Trips... try setting them to 1-Trip.

Some of your B1S1 and B2S1 O2 DTC's are set to Not-Reported... compare these to say a stock 2002 Camaro file.