Longtubes

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06-10-2023
BROWNSTONE

CL fueling and O2 distance/response w/Longtubes

Hello everyone!
2000 rcsb 5.3: 11.8cr, 231 int dur., 2" primaries.

I am new to HPT so just wanting to ask a couple of specific questions to see what your experiences might help with...

I have the truck dialed in well for OL operation holding at 14.4 - 15.0 on my WB for MAF and SD separately pretty well throughout my range, and even have started some WOT and PE edits. My challenge is as follows:

As I begin to attempt utilizing dynamic airflow and CL- I am going lean on idle snd in the lower ranges below 2500 rpm.

My truck has a lot 3-4X) more volume in the header compared to stock manifolds, plus the O2's are farther away...

I have started experimenting with the O2 rich/Lean switchpoints. I believe I understand what this mV setting does, so I am not really convinced this is the best or correct way to compensate or offset for the header volume and exh. Gas pulse time effect. Do you think this is sound logic? Just trying to decide how much or if the tables should be changed.

Also, I have begun looking at the proportional integral timer. Is this the correct way to address exhaust o2 read time? Initial edits are definitely indicating it has a significant effect on my CL stft's... Does anyone have ideas on how to do this?

Finally, and maybe most interested in- is there a good way to scan either of these parameters which would help yield the best edits or trims for these? Thought about a histo plotting a percentage error between the stock O2's vs the AEM, but really needing a time- in milliseconds I think...

Surely some of you have dealt with, and likely many times! 😉

Thanks for any comments!!
06-10-2023
horsepowerguru427

do you have exhaust past the headers or is it just open headers? also, youre gonna hear this everytime you post on here, post the tune and a log if you got it.
06-11-2023
BROWNSTONE

2 Attachment(s)

Quote:

Originally Posted by horsepowerguru427

do you have exhaust past the headers or is it just open headers? also, youre gonna hear this everytime you post on here, post the tune and a log if you got it.

Currently it has the Speed Eng. Y-Pipe installed and nothing past that, no exhaust yet.. I am thinking this is response time for the CL instrumentation, but am not familiar, and not really certain where to start on this portion... thanks in advance..

Attaching tune and log here:
06-11-2023
BROWNSTONE

Quote:

Originally Posted by BROWNSTONE

Currently it has the Speed Eng. Y-Pipe installed and nothing past that, no exhaust yet.. I am thinking this is response time for the CL instrumentation, but am not familiar, and not really certain where to start on this portion... thanks in advance..

Attaching tune and log here:

I have adjusted switch-points a coup
06-12-2023
horsepowerguru427

Im looking through your tune at the moment but to be honest with you, youll get much better idle and mid throttle results if you use STFT, LTFT or LTFT+STFT math to collect data and make changes to VE and MAF. WB is great for WOT and PE and actually the only way to accurately adjust these. I personally prefer to use STFT in OL to tune. I hope when you were collecting data for VE and MAF adjustments you had COT, PE, DFCO turned off and never went into WOT, otherwise your data is junk and isnt accurate either.

Also, as long as you have at least 18" of pipe after the O2s then it should be ok and reading pretty accurate, assuming the O2s are working properly.

If it was me ID set my switch points to 450ish and set the other O2 settings to factory and recalibrate everything using OL STFT and everything should smooth out...

be sure your resetting the Fuel trims in the specials features of the scanner before you log anything. not clearing trim data will result with inaccurate data that isnt good to use either...
06-12-2023
BROWNSTONE

Ok thanks, great info.. yes had all that turned off and I believe properly isolated both VE and then MAF. I also tune with P.E. turned off and then I do that last with WOT pulls.... I have been using the WB and calculating % error from stoich. Seems there are a couple of philosophies, maybe I will try re- logging my VE using stft... but seems this may still result in the same delta betw. WB and stocks.. I just have a gut feeling these 2" primaries are contributing to this variation since lots more volume...
06-12-2023
horsepowerguru427

2" primaries are going to slow your exhaust velocity down a lot especially at low rpm unless you have a ton of cubes or forced induction, honestly. Yes, you are correct. there is not just one way to tune things and there are lots of different opinions on what works best. Ive tried almost every "philosophy" as you call it and i get the best response and fuel trims from using STFT, but there will be someone who says different. it never hurts to try something and apply it and if it doesnt work well then you can go back to your previous tune.
06-12-2023
GHuggins

Quote:

Originally Posted by horsepowerguru427

2" primaries are going to slow your exhaust velocity down a lot especially at low rpm unless you have a ton of cubes or forced induction, honestly. Yes, you are correct. there is not just one way to tune things and there are lots of different opinions on what works best. Ive tried almost every "philosophy" as you call it and i get the best response and fuel trims from using STFT, but there will be someone who says different. it never hurts to try something and apply it and if it doesnt work well then you can go back to your previous tune.

YES what he said :D Don't be afraid to experiment to see what does what AND what works best for you... I also believe Cringer referred you to his vid for tuning the O2's. If nothing else it will help guide you on what your adjusting and why... It is very long though - I'm only half way though it right now but the part I saw was good info and how we do it :)
06-12-2023
BROWNSTONE

Quote:

Originally Posted by horsepowerguru427

2" primaries are going to slow your exhaust velocity down a lot especially at low rpm unless you have a ton of cubes or forced induction, honestly. Yes, you are correct. there is not just one way to tune things and there are lots of different opinions on what works best. Ive tried almost every "philosophy" as you call it and i get the best response and fuel trims from using STFT, but there will be someone who says different. it never hurts to try something and apply it and if it doesnt work well then you can go back to your previous tune.

Agree.. 5.3L... not a lot of cubes so yes... I think I may log a stft histo and tune it in on both maf and ve. Worth a shot. Appreciate the ideas and conversation!
06-12-2023
BROWNSTONE

Stft

Quote:

Originally Posted by horsepowerguru427

2" primaries are going to slow your exhaust velocity down a lot especially at low rpm unless you have a ton of cubes or forced induction, honestly. Yes, you are correct. there is not just one way to tune things and there are lots of different opinions on what works best. Ive tried almost every "philosophy" as you call it and i get the best response and fuel trims from using STFT, but there will be someone who says different. it never hurts to try something and apply it and if it doesnt work well then you can go back to your previous tune.

Agree.. 5.3L... not a lot of cubes so yes... I think I may log a stft histo and tune it in on both maf and ve. Worth a shot. Appreciate the ideas and conversation!