O2 transport delay

[JimMueller]

Does anyone have a definitive step-by-step guide on how to get factory-quality closed loop operation after installing long tube headers? I've read the following thread but my calibration has fewer tables than what Gary posted for his Gen3 tables.

https://forum.hptuners.com/showthrea...g-with-headers

I've multiplied my O2 integrator delay by 1.35 (based upon a FB group suggestion) and still have long periods of flatlining both high and low. Do I blindly keep increasing that table until the flatlining stops?

[JimMueller]

Bump - I am hoping to make progress on this while I'm off work this week.

[JimMueller]

bump

[murfie]

You could fix this with just cleaning up your MAF transfer, and getting your fuel trims closer to 0 for LTFT, and bouncing between+2 and -2 for STFT.

Right now its looking like you could start by taking out 8-10% from your MAF transfer, and just generally smoothing it out.
14.37 is a strange stoich, what fuel are you using?


take this

Original MAF curve.PNG

and make it more like this

smoothed MAF, -8%.PNG

Then watch your fuel trims, and compare it to a graph with the axis of your MAF frequency from your HPT file. You should add that PID to your scanner.

LTFT 8-10%.jpg

Then set it up to use CL more than OL. 75% throttle, instead of, 50 and going down with higher RPMs. OL should be used for PE during a high load condition only thing. Stoich is perfectly safe for 75% load or less, and even more if you give it time to cool off and its not detonating.

[JimMueller]

The OLMAF (attached) log was +/- 3% the week prior, pretty close and what it wants. I lean towards what it wants instead of a perfect polynomial curve so long as there are not significant fluctuations. Stoich is 14.38 due to local E10 pumps containing about 5.5% ethanol in a test kit. I need the O2 sensors to switch reliably before I can use fuel trims to clean up idle & part throttle.

[murfie]

Narrow band O2 sensors, just output what they are sensing. The switching comes from the ECU and fuel trim logic. The less it has to work, the better the switching will be.

Dial it in to what your narrow bands want for stoich. confirm your WB agrees with them, then only use the WB to dial in the PE, where the NB's cant see.

If you want factory quality cl operations, tune to the narrow bands the factory calibration uses.

[Digital Corvette]

Suggest that you increase the Proportional Idle O2 Error. Mine starts a 1.0 and increases to 2.0 (the max permitted value). Increasing the value makes the ECM vary the fuel more dramatically at idle to get the O2 sensors to oscillate. I can observe this at idle as the air/fuel ratio moves above and below stoich. Your proportional airflow looks OK.

[JimMueller]

From the original post, actual modify dates on the files:
10/3/2021 7:42PM - "03oct2021_CL1.hpl"
10/5/2021 1:47AM - "Blend_baseline_Oct03_2021.hpt"

I found this additional calibration I attempted to create from the old link in the first post, but it appears I was skeptical on it working and didn't try it. It has Prop Idle O2 Err maxed out at 2.0 across the board, should I try running this config as-is, or make add'l adjustments?
10/8/2021 4:05AM - "Blend_O2_Testing".hpt"

[JimMueller]

* I loaded the tune from post #8, and that generated log "cl1_o2err_2-2"
* I changed Prop Idle O2 Err to interpolate between 1 and 2, and that generated log "cl1_o2err_1-2"
* I changed the Mode vs Airflow table back to stock, and that generated log "cl1_o2err_1-2_Airflow"

Comments on the last log:
* The 'load vehicle defaults' option did not pick the correct TPS PID, so it's not logged

* I'm happier with the O2 oscillation. Can the CL parameters be further improved before I start using STFT+LTFT to tune idle & part throttle?

* My LTFT's are enabled, but the boundaries (55/67/80 MAP,) and RPM (1000/1700/2400) are not being met. Is the following post still correct on how to set LTFT boundaries? I'll try changing the MAP to 60/70/80 and RPM to 900/1650/2400.
https://forum.hptuners.com/showthrea...TFT-boundaries

* When I abruptly let off the throttle, DFCO seems to be too aggressive, jerking the car. It seems to be worse at higher RPMs even in part throttle. It's been a very long time since I drove with DFCO enabled so I don't not recall the expected behavior.

* Had one mild backfire at a relatively slow speed through a residential neighborhood.

[murfie]

You are happier with the switching, Great!

Do you see how the FT's are not moving, yet the O2's are indicating rich while you are cruising?

Do you also see how FT's need to swing -15 to +15 now at idle to get the O2's swinging?

IMO you are not making this better, its gotten much worst.
Leave the PID stuff alone.
Match your zoning to fit your modifications better. Things that changed MAP range and RPM range.

O2 vs FT.jpg

[JimMueller]

You are happier with the switching, Great!
Match your zoning to fit your modifications better. Things that changed MAP range and RPM range.

Do you have very detailed steps to complete this process? Would it be premature to attempt to adjust idle/PT airflow based upon fuel trims prior to completing the airflow & zone adjustments?

I made the LTFT changes but no joy. I could simply be impatient, I'll see if I can put 50 miles on it without wanting to alter something else. I tweaked DFCO as well and will monitor.

[JimMueller]

Getting a P0155 now, will check the harness and sensors. What is the consensus on the best O2 sensors to use in the S1 positions? Delphi? GM? Regarding optimizing the sensor switching, still only finding vaguely described methods to correct it so CL fueling can be corrected with long tube headers. This is like 20 years ago where vendors wouldn't publish their custom camshaft specs, or certain vendors that won't publish wheel offsets. Ludicrous.

[blindsquirrel]

GM-boxed sensors are made by either NTK or Denso. Choosing by price is OK as long as you stick to one of those 3.

[JimMueller]

In this AFS123 sensor review (with photos), a person commented that he added aluminum foil to help them heat up better. Yay or Nay?

https://www.amazon.com/gp/customer-r...SIN=B0016IKVPO

[blindsquirrel]

Since aluminum is such a good conductor of heat, I would not be surprised if hackery like that would actually suck away and dump more heat than it traps.