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Thread: LS7 Trying to Use LTFT Tuning Until...

  1. #1
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    LS7 Trying to Use LTFT Tuning Until...

    Newbie here trying to finalize removal of A&A V-3 Supercharger from 07 Z06. Engine was dyno tuned by installation shop (S/C & AHP 116 cam, no headers) in Delaware in 2015. After I did s/c removal, engine actually runs good but I knew calibration couldn't be optimum. I know a wideband will ultimately be needed but as yet am concerned about where to place sensor since I don't have header bungs:

    1. So my 1st question is how much of a compromise would using a post-cat 02 sensor bung be? They are tuned out.
    2. My LTFTs are dancing -3s to -5s, so trying to figure best way to improve, wondering about condition of 02 sensors, thinking about swapping side to side.
    3. I followed a couple tutorials on setting up histograms for LTFT logging & could not get the MAF version to populate. Is that function not available for Gen4?

    Attached tune & log hoping someone might take a look & advise.
    Attached Files Attached Files

  2. #2
    Tuning Addict blindsquirrel's Avatar
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    You have to log the channel for MAF Hz for the LTFT+STFT graph to work, and MAF Hz isn't in your channels. The 'Mass Airflow' PID is what's calculated after the ECM does the math for Hz vs MAF table, so you can't use that to fix the table.

  3. #3
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    1) Wideband should be in front of the catalytic converter. If you're worried about dropping the exhaust and welding there are clamp-on adapters.
    https://www.aemelectronics.com/produ...-sensor-mounts

    2) STFT's are pulling a lot of fuel, and knock is occurring there. I don't think LTFT's have had a chance to update yet. Re-do airflow using both LTFT and STFT.

    3) For the VVE side of airflow tuning:
    https://forum.hptuners.com/showthrea...6621#post41662.

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    Quote Originally Posted by blindsquirrel View Post
    You have to log the channel for MAF Hz for the LTFT+STFT graph to work, and MAF Hz isn't in your channels. The 'Mass Airflow' PID is what's calculated after the ECM does the math for Hz vs MAF table, so you can't use that to fix the table.
    Don't know much but did know to add the Maf Hz channel & did but must have removed it somehow. Just dumb on my part, Sorry. You guys have your own language & I'm sure us newbies drive you crazy. Thanks so much.

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    Thanks so much for your reply. I was aware if the clamp adapter but my issue is I'm dealing with the cast iron exhaust manifold. The info will be most helpful, the link is concise & I think it'll get me moving along. Directions are on-point, Thanks Again!!

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    Quote Originally Posted by SiriusC1024 View Post
    1) Wideband should be in front of the catalytic converter. If you're worried about dropping the exhaust and welding there are clamp-on adapters.
    https://www.aemelectronics.com/produ...-sensor-mounts

    2) STFT's are pulling a lot of fuel, and knock is occurring there. I don't think LTFT's have had a chance to update yet. Re-do airflow using both LTFT and STFT.

    3) For the VVE side of airflow tuning:
    https://forum.hptuners.com/showthrea...6621#post41662.
    I'm sorry but I indicated the exhaust manifolds were cast iron but they are actually stainless steel, worried about drilling into it & accessing flow, need to get one off & take a closer look. I have to pay more attention to detail, until your comment I had not noticed the KR in the Chart vs Time. Can't wait to redo airflow with the new instruction. Hoping I don't have a bad o2. Thanks!!

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    o2's look ok to me. They seem to be oscillating fine. Just to be clear; you are naturally aspirated now? If so, what intake are you running? Add Cylinder Airmass, Volumetric Efficiency, and Dynamic Air channels to your scanner.

    Under the Fuel tab, 0 out your PE delay. Under the Air Flow tab, MAF Calibration high and low tables should be the same value @ 5800hz.
    Last edited by LS ROB; 05-23-2023 at 12:40 PM.

  8. #8
    Tuning Addict blindsquirrel's Avatar
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    Quote Originally Posted by LS ROB View Post
    change the Enable Min. Map to something lower, around 40.
    That would probably be not so great, log shows idle is at ~45kPa. It'd basically have PE turned on anytime the engine was running and throttle went over 25%. Better to have PE work as a load-based thing, and load is directly related to MAP. Map not high, not enough load to need enrichment.

    PE Min MAP at 70-80kPa. Throttle 70% at low RPM, sloping down to 20-30 at high RPM. An N/A engine doesn't need anything close to that rich (1.126 with a Stoich of 14.68 is 11.65:1; it gets worse at 5,500 (10.56:1) and continues to get worse from there, 8.5:1 @ 6,750 (rev limiter is at 7,100)). Whole table set to 1.16 or 1.18 is fine for N/A.

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    Quote Originally Posted by blindsquirrel View Post
    That would probably be not so great, log shows idle is at ~45kPa. It'd basically have PE turned on anytime the engine was running and throttle went over 25%. Better to have PE work as a load-based thing, and load is directly related to MAP. Map not high, not enough load to need enrichment.

    PE Min MAP at 70-80kPa. Throttle 70% at low RPM, sloping down to 20-30 at high RPM. An N/A engine doesn't need anything close to that rich (1.126 with a Stoich of 14.68 is 11.65:1; it gets worse at 5,500 (10.56:1) and continues to get worse from there, 8.5:1 @ 6,750 (rev limiter is at 7,100)). Whole table set to 1.16 or 1.18 is fine for N/A.
    You're right. I must have been thinkin about vacuum @ WOT. Good catch squirrel.

  10. #10
    Tuning Addict blindsquirrel's Avatar
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    Typo in my last there - I think his PE is actually 1.26, not 1.126. It's stupid rich if it's able to actually deliver what it's asked to.

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    Quote Originally Posted by Les10 View Post
    Newbie here trying to finalize removal of A&A V-3 Supercharger from 07 Z06. Engine was dyno tuned by installation shop (S/C & AHP 116 cam, no headers) in Delaware in 2015. After I did s/c removal, engine actually runs good but I knew calibration couldn't be optimum. I know a wideband will ultimately be needed but as yet am concerned about where to place sensor since I don't have header bungs:

    1. So my 1st question is how much of a compromise would using a post-cat 02 sensor bung be? They are tuned out.
    2. My LTFTs are dancing -3s to -5s, so trying to figure best way to improve, wondering about condition of 02 sensors, thinking about swapping side to side.
    3. I followed a couple tutorials on setting up histograms for LTFT logging & could not get the MAF version to populate. Is that function not available for Gen4?

    Attached tune & log hoping someone might take a look & advise.

    1. I'm going to take heat for this.. but AFR doesn't change across a cat.. No fuel and no air entered or left the system. Any difference in how it reads would be due to the temperature/pressure difference between the two spots. But the AFR does not change in a cat. Also.. during PE the condition the wideband is useful for.. the mixture is rich.. There is no left over O2.. The cat couldn't burn anything if it wanted to because there is no left over O2. Its better if it is closer to the engine.. It is reasonable to use a post cat spot.

    2. The LTFTs in this log are pretty damn close.. They will never be zero and they won't be exactly the same day to day.

    3. The reason why you are not able to make a MAF graph about this is because you are not logging MAF frequency HZ
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    Fuel Trims swing from rich to lean

    Newbie is Lost Big Time. Initially I was at -3s to -5s LTFTs. After playing around with the MAF & VVE fuel trim tuning my log showed lean fuel trims instead of rich. Thinking that I did something wrong, I put the original tune back in & the result is still lean STFT & LTFTs. Fuel pressure seems consistent. Do I have some mechanical issues, 02s, injectors, etc.? What am I missing here? I'm attaching the log & tune I previously sent (Baseline with 08Timing,Forum.hpl&.hpt) and the latest log of the same tune (verification#3.hpl). Thanks!
    Attached Files Attached Files

  13. #13
    Tuning Addict blindsquirrel's Avatar
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    Trying to adjust MAF & VVE at the same time/with the same tune file settings?

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    Look up rich after flash - your itt table is zeroed out - why you went lean after loading a tune into a hot engine.

    The only way having it post cat might change things is the time delay flowing through it and if there's any raw fuel at all as that'll burn going through the cat. Otherwise post cat is better than stuck in the tailpipe - which is what a lot of dyno tuners use and will work just fine. I always tell customers it's better to be pre-cat, but if it's not possible do post...
    2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
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    Thankfully Some Progress, Still Need Lots of Help

    1. Researched for 'rich after flash' & found Injector Control Offset 'Offset vs Inj Temp' which I think is whats being talked about, & Yes mine is zeroed. Problem is I can find instructions on setting it up.
    2. Made sure engine was cold before flashing attached tune (FlashExp1withVEHisto) using graph from previous Log (Experiment1verification)--Logging resulted in continued Lean fuel trims (Log1withVEHisto).
    3. Copied graph from (Log1withVEHisto) & pasted into tune (FlashExp2withVEHisto) VVE table. (Log2withVEHisto) showed fuel trims swinging back rich, so am somewhat relieved that my process is at least working/changing things.

    Note: When doing these tunes I have been following instructions from online videos having me 'disabling' SD by minimizing Dynamic Airflow 'High RPM Disable' & 'High RPM Re-enable'. Addionally I am maxing out 'Deceleration Fuel Cutoff Enable & Disable ECT', maxing 'Cluch Fuel Cutoff Enable VSS' and lastly 'Disabling Catalyst Protection COT'. Please Advise if I'm on the right track here.

    4. Hoping to do the MAF calibration with Fuel Trims tomorrow.
    So when I paste the graph (histogram?) info into the VVE table, My next attempt is pasted into the VVE that I modified the last time, & so-on & so-on correct?

    5. I see where I'm getting some knock, is this something that needs fixing soon & if so how? Sorry but the more I read the more I realize how little know. I am serious so I got to get my wideband approach method resolved. By the way, which wideband?

    You Folks have been Great, Thanks!!
    Attached Files Attached Files

  16. #16
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    Quote Originally Posted by Les10 View Post
    1. Researched for 'rich after flash' & found Injector Control Offset 'Offset vs Inj Temp' which I think is whats being talked about, & Yes mine is zeroed. Problem is I can find instructions on setting it up.
    2. Made sure engine was cold before flashing attached tune (FlashExp1withVEHisto) using graph from previous Log (Experiment1verification)--Logging resulted in continued Lean fuel trims (Log1withVEHisto).
    3. Copied graph from (Log1withVEHisto) & pasted into tune (FlashExp2withVEHisto) VVE table. (Log2withVEHisto) showed fuel trims swinging back rich, so am somewhat relieved that my process is at least working/changing things.

    Note: When doing these tunes I have been following instructions from online videos having me 'disabling' SD by minimizing Dynamic Airflow 'High RPM Disable' & 'High RPM Re-enable'. Addionally I am maxing out 'Deceleration Fuel Cutoff Enable & Disable ECT', maxing 'Cluch Fuel Cutoff Enable VSS' and lastly 'Disabling Catalyst Protection COT'. Please Advise if I'm on the right track here.

    4. Hoping to do the MAF calibration with Fuel Trims tomorrow.
    So when I paste the graph (histogram?) info into the VVE table, My next attempt is pasted into the VVE that I modified the last time, & so-on & so-on correct?

    5. I see where I'm getting some knock, is this something that needs fixing soon & if so how? Sorry but the more I read the more I realize how little know. I am serious so I got to get my wideband approach method resolved. By the way, which wideband?

    You Folks have been Great, Thanks!!
    Hey Les, you can flash a tune in while the engine is warm/hot; it doesn't have to be cold/cool but you do want to drive around for about 15 min. before starting to log any data. As for MAF & VVE, you will want to do each separately. Copy from the MAF graph in the scanner & paste % half into the MAF table in the tune. Same goes for VVE. Just remember, when doing these separately, you need to disable the other. Tuning MAF=disable VVE and make changes to the MAF table. Tuning VVE=disable MAF and make changes to VVE table. These guys on here can tune both of those tables at the same time but as a novice, ive found it easier to start with the basics. And yes, you are on the right track with disabling half the tune before logging lol


    if you would like, you can flash this to see if it helped. I tweaked the MAF based on your log "Log2withvehisto." If you flash this, then do a log, you should be able to see a pretty good difference with the next revision. This one i just copied your data from the MAF graph, pasted % half then smoothed to get it heading in the right direction.

    FlashExp2withVEHisto-maf low.hpt
    Last edited by LS ROB; 05-24-2023 at 08:51 PM.

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    To dial in fueling for hotter injector tip temps - find a stock ls7 car file with it populated - copy and paste that into yours - if you're running bigger injectors go ahead and cut those values by .5 or .6. Now set your engine up to idle at around 1000 rpms - this will get airflow disturbances caused by a cam out of the picture - get the engine to temp from a cold start - see what your average fuel trim is at hot elevated idle (this is what you'll target) - now flash your ecm with the engine being hot and log fuel trim corrections for the next 20 minutes of runtime or until tip temp comes back down to it's lowest value - pull or add fuel. Depending on your injector size you may need to add .015 ms worth of fuel or .0078ms worth of fuel to correct a 2%ish error. Then repeat until you're happy with the outcome.
    2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
    2011 Vette Cam Only Internal Mod in stock LS3 -- YSI @ 18psi - 811rwhp on 93 / 926rwhp on E60 & 1008rwhp with a 50 shot of nitrous all through a 6L80

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  18. #18
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    Quote Originally Posted by Les10 View Post
    1. Researched for 'rich after flash' & found Injector Control Offset 'Offset vs Inj Temp' which I think is whats being talked about, & Yes mine is zeroed. Problem is I can find instructions on setting it up.
    2. Made sure engine was cold before flashing attached tune (FlashExp1withVEHisto) using graph from previous Log (Experiment1verification)--Logging resulted in continued Lean fuel trims (Log1withVEHisto).
    3. Copied graph from (Log1withVEHisto) & pasted into tune (FlashExp2withVEHisto) VVE table. (Log2withVEHisto) showed fuel trims swinging back rich, so am somewhat relieved that my process is at least working/changing things.

    Note: When doing these tunes I have been following instructions from online videos having me 'disabling' SD by minimizing Dynamic Airflow 'High RPM Disable' & 'High RPM Re-enable'. Addionally I am maxing out 'Deceleration Fuel Cutoff Enable & Disable ECT', maxing 'Cluch Fuel Cutoff Enable VSS' and lastly 'Disabling Catalyst Protection COT'. Please Advise if I'm on the right track here.

    4. Hoping to do the MAF calibration with Fuel Trims tomorrow.
    So when I paste the graph (histogram?) info into the VVE table, My next attempt is pasted into the VVE that I modified the last time, & so-on & so-on correct?

    5. I see where I'm getting some knock, is this something that needs fixing soon & if so how? Sorry but the more I read the more I realize how little know. I am serious so I got to get my wideband approach method resolved. By the way, which wideband?

    You Folks have been Great, Thanks!!
    completely fine leaving the ITT table zeroed. There are lots of factory calibrations like this from the factory. If you decide to keep it populated be sure to throw out the first 15 minutes of data as the calculation for ITT gets messed up with a re flash. It will run abnormally rich until this calculation (which we can't see) works itself out. If you have large injectors this is enough to start fouling plugs at idle.

    Far better to leave it zeroed IMHO.
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  19. #19
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    Been Barking Up the Wrong Tree??

    Quote Originally Posted by LS ROB View Post
    Hey Les, you can flash a tune in while the engine is warm/hot; it doesn't have to be cold/cool but you do want to drive around for about 15 min. before starting to log any data. As for MAF & VVE, you will want to do each separately. Copy from the MAF graph in the scanner & paste % half into the MAF table in the tune. Same goes for VVE. Just remember, when doing these separately, you need to disable the other. Tuning MAF=disable VVE and make changes to the MAF table. Tuning VVE=disable MAF and make changes to VVE table. These guys on here can tune both of those tables at the same time but as a novice, ive found it easier to start with the basics. And yes, you are on the right track with disabling half the tune before logging lol


    if you would like, you can flash this to see if it helped. I tweaked the MAF based on your log "Log2withvehisto." If you flash this, then do a log, you should be able to see a pretty good difference with the next revision. This one i just copied your data from the MAF graph, pasted % half then smoothed to get it heading in the right direction.

    FlashExp2withVEHisto-maf low.hpt
    Rob I appreciate your time & your help. I did another post a little earlier out of desperation on the very BASICS of the whole tuning deal, I feel so dumb. The more I read I'm now thinking that the disabling of VVE to tune MAF & disabling of MAF to tune VVE is in preparation of doing the data-logging to gather data for updating the tune in editor. I have been attempting to disable SD to tune for VVE which I'm now thinking voids everything I have done so far. I didn't realize that SD & VVE were same and/or they worked in closed loop. After you make changes to your tables in your tune how do you set the things you changed for disabling?
    You mention the disabling of VVE & MAF for the respective tuning, can you explain the proper way to do each? Thanks!

  20. #20
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    I took a look at your other thread and yes, you're process to disable VVE and MAF is correct. Edit your "as found" file and name it something different when saving; something like "Speed Density." If you save it as "as found" you will loose your stock file and you always want it to revert back to if needed. I'm attaching a screenshot of the different engine modes which helped me starting out. (still a novice with limited knowledge)

    Once you disable the VVE side of things, you will be tuning MAF. Now, your scanner has to be set up to to capture the data. You will need to log the Mass Airflow Sensor channel and make sure the unit is in hz. Also, log the channel Mass Airflow (SAE). Then you will set up your graph. Basically, you open your tune in editor, highlight and copy the columns and paste those into the graph in the scanner. You may have to right click on the graphs tab and go to "graphs layout." Click the icon of a graph with the + sign on it and add table. Click on the graph that populated on the left hand of the layout and fill it out like the one in the photo i have attached. Others may chime in and say there is a better way but at least you'll get the feel for creating your graphs. That should get you to where you can grab some data. Then, highlight the data>right click>copy. Then highlight the table in Editor>right click> multiply % half and smooth. Hope this helps. I'm not the greatest at explaining things haha!




    engine modes2.jpg

    maf table.jpg

    MAF table2.jpg