PLEASE HELP - 02 sensor switchrate and AFR range after LT headers

[Pat376]

I'm new to this tuning and I'm pulling my hair out trying to solve a problem with my O2 sensor/AFR range in CL.

I've dialed in my MAF, VVE, Timing, and PE so far but once I turn CL back on I have an excessive AFR oscillation range.
This is observed on my AEM 30-0334 wideband after installing ARH 1-7/8" LT headers with Cats on my 2012 Corvette Grand sport.

I've tried to adjust the Proportional limits between the stock 2.000 to 1.000 to 0.500 with no noticeable difference.
I've tried to adjust the Proportional vs Airflow down 5% across the board with no noticeable difference.
I've tried to adjust the Integrator delay up 10%, 15% and 20% with the only change being the switching is spaced slightly further apart on the o2 sensor voltage wavelengths.
I've tried changing the 02 limits from 550max/350min to 450max/450min MV.

I have not turned off the rear 02 sensors, and the 02 sensor R/L bank 1/2 tables I have not touched. Do I need to set these to 450mv across the board? Currently I have all the O2 sensor settings back to stock.

Attached are images showing the AFR swing as well as a stock cruising datalog before I installed the wideband sensor.
The AFR ranges from 13.8 to as high as 16.0 sometimes but generally between 14.0 and 15.8. Is there any way to adjust this to stay within 14.4-15.0 range? This large range is present at idle all the way to cruising at 1800rpm as far as I've noticed.

Anybody that helps me solve this issue I'll paypal them some money for their time and help. THANK YOU!

[RobZL1]

Would help us immensely if you showed us your O2 sensor oscillation in mV or V on these graphs.

[blindsquirrel]

Or upload the actual logfile instead of a photo of a screen.

[Pat376]

Or upload the actual logfile instead of a photo of a screen.

I have attached the log where all I changed was the 450/450 min max mv, I did not adjust the R/L bank 1 and bank 2 at all.

[Pat376]

Here are two more datalogs of the car sitting in the driveway. I tried changing the switchpoints from the ultra low settings to 328mv across the board then 450mv across the board. Didn't seem to have any affect. Please if anybody has any ideas this is driving me crazy.

All other O2 sensor settings were left stock during these tests.

[blindsquirrel]

Do you have any apparent issues other than an expectation of what it should look like in the logs? I honestly don't see anything abnormal there. The slower switching is pretty much inevitable with the sensors now located 3 or however many times farther downstream than they were stock.

[Pat376]

While the car is idling you can feel as the AFR is hitting the minimum and maximum values in the 13.8 - 16.0AFR range.

I'd rather have my engine run smoothly at idle and from a stop as it does in open loop. Over 20 points range just seems so excessive and I have seen other threads where people mention only a 5 point swing.

But again, I'm new to this so is this large of a range present on most people's cars in CL? Also what would be the best way to set the car to run OL at idle only, if this large range is normal? Thank you.

[TheMechanic]

In a stock software setting the factory wants as high a switching (cross counts) as possible. Allows the best scrubbing from the cats (rich/lean cross counts enable CO, HC, and NOx reductions). As to idle the factory wants a very slight lean miss for a reduction in CO. This is all for emissions. Driveability is secondary to emissions. I'm in agreement with blindsquirrel's statement. Only way you will change is to fatten the idle or you could move the B1S1 and B1S2 upstream on a primary but that would be very counterproductive.

[ABADZL1]

Try going lower with closed loop proportional limit. Start with something like .050 . (Not the .500) It tightened up my fluctuation nicely, and a lot of other cars I've done.

[Pat376]

Try going lower with closed loop proportional limit. Start with something like .050 . (Not the .500) It tightened up my fluctuation nicely, and a lot of other cars I've done.

Thank you, I will try 0.050 on the proportional limit. That would make sense if the stock limit is 2.000 but realistically the computer is never exceeding 0.500, which is why I didn't notice a change.

Should I keep the rest of the settings stock for now until I see how the o2 sensors react to this change or is there a better baseline to start at with the R/L Bank 1 and 2, proportional airflow and transient delay?

[Pat376]

In a stock software setting the factory wants as high a switching (cross counts) as possible. Allows the best scrubbing from the cats (rich/lean cross counts enable CO, HC, and NOx reductions). As to idle the factory wants a very slight lean miss for a reduction in CO. This is all for emissions. Driveability is secondary to emissions. I'm in agreement with blindsquirrel's statement. Only way you will change is to fatten the idle or you could move the B1S1 and B1S2 upstream on a primary but that would be very counterproductive.

Thanks for the information

[Pat376]

I did not have luck with lowering the proportional limit to 0.050, the fuel adjustments just seemed to get much slower but still ranging 13.9-15.9 AFR.

If the integrator delay makes the 02 sensors hang longer at min/max MV's, would halving this number shorten the wavelengths and allow the STFT to make faster corrections and possibly catch the AFR swings earlier which would lower the range I'm seeing?

Is anybody just running OL at cruising speeds with high flow cats, or is there too large a risk of clogging the cats overtime? Any help is greatly appreciated.

[Alvin]

Try multiplying ECM 12480 by 0.25 from stock values
and ECM 12470 by 4.0 from stock values. Put all O2 tables back to stock.

[pannetron]

These settings work well for me in CL with long tube headers and a LPE GT9 cam, keeping idle AFR swings mostly between 14.0 and 15.8. With the O2 switching voltages I have set, this yields an average lambda at idle and cruise of 1.02. The GT9 cam has little overlap and a big exhaust lobe but it idles nicely.

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