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Thread: lean area around 2500ish rpms-2014 ctsv

  1. #1
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    lean area around 2500ish rpms-2014 ctsv

    Hi guys,

    I've brought this up previously but still couldn't figure it out. no matter what i do to my maf curve i cannot tune out this repetitive lean area. Below is just one example throughout the log that this happens. I noticed that it seems like the 02 sensors aren't switching fast enough..every time this lean condition happens there is a large gap from when the o2 voltages switch. I've tried messing with the 02 sensor settings (proportional/integral delay) with limited amounts of success. Is there any other 02 sensor setting that i could try and adjust to get rid of that large delay that i'm seeing. In this log i actually cut the delay down by 30% and you can see right after that lean area the o2s start switching really fast (almost too fast). i'm leaning towards 02 sensor settings, but i just can't figure out what i need to adjust to correct the problem. I don't have headers so i didn't think i needed to adjust the 02 sensor settings at all. Any other input on this would be appreciated.

    -test pipes
    -2.35" pulley
    -I.d. 850 injectors
    -ported blower
    -airaid

    2500ish rpm lean area.PNG2.35 pulley, ID850s, CURRENT TUNE HUMPLESS SPARK TABLE interpolated higher spark cells.hpt
    Last edited by sgod1100; 09-12-2020 at 05:05 PM.

  2. #2
    Tuning Addict blindsquirrel's Avatar
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    What's the throttle dip right before it happens each time - are you lifting the pedal or is it doing that on its own?

  3. #3
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    Quote Originally Posted by blindsquirrel View Post
    What's the throttle dip right before it happens each time - are you lifting the pedal or is it doing that on its own?
    M6 trans

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    wanted to bump this.....here is a log at WOT 2-3k rpms and it has the exact same condition going on. This is maf only as I disable dyn. air. I'm almost leaning toward an injector issue maybe?? Any seasoned tuners on here care to help out? I'm at a loss. TIA 2.35 pulley, ID850s, CURRENT TUNE HUMPLESS SPARK TABLE interpolated higher spark cells.hpt
    2-3k rpm lean area WOT.hpl
    Last edited by sgod1100; 09-27-2020 at 01:13 PM.

  5. #5
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    updated: I added the % fuel error and now it's much closer....however, now i have a decent hump in my maf curve. I'm also willing to bet that once i hit those "hz's" cells at a different throttle position (still in PE) other than WOT it's probably going to be extremely rich.added fuel in 2-3k range.hpl2.35 pulley, ID850s, CURRENT TUNE HUMPLESS SPARK TABLE interpolated higher spark cells.hpt

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    no one else with a ctsv has experienced this problem? damn...

  7. #7
    Advanced Tuner PGA2B's Avatar
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    Mine does it too when I first enter PE until it catches up to commanded. Fast forward to 4:05 into the log. I've tried to add fuel to fix but then under normal load it is super rich. Currently MAF only as well.
    Attached Files Attached Files
    Last edited by PGA2B; 09-29-2020 at 07:24 PM.
    2013 OBM A6 CTS-V Coupe
    Mods: Headers back Billy Boat Exhaust, GripTec 2.65, 8.6 PowerBond Lower, LSX Innovations Solid Isolator, ID850's, NGK TR7IX's, Accel 9070CK Wires, Spectre CAI, SRI Ported Throttle Body, SRI Catch Can, NGK AFRM, 160* T-Stat, 0fx2gv Brick, Hard Line Delete W/3/4" Lines, FB 101 FMIC, Pierberg CWA50, Stoptech Drilled/Slotted Rotors, EBC Redstuff, Cut Stock Springs, Flat Bottom Steering Wheel
    2006 Black Raven STS-V (Traded In)
    Fully Modded: 459RWHP@5888rpm/451lbft@4696rpm

  8. #8
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    Quote Originally Posted by PGA2B View Post
    Mine does it too when I first enter PE until it catches up to commanded. Fast forward to 4:05 into the log. I've tried to add fuel to fix but then under normal load it is super rich. Currently MAF only as well.
    Mine is happening during closed loop though..approx 60-80 kpa. I can feel it as well...like a slight surge

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    bump...244 views and no one has any idea? I'm all ears and willing to try anything at this point

  10. #10
    Advanced Tuner PGA2B's Avatar
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    Check with RobZL1 as I remember a post where he talked about his struggles with this. BTW- I also am dealing with it in closed loop. If I add too much fuel or take too much out I can feel it so I have been trying to find the happy medium.
    2013 OBM A6 CTS-V Coupe
    Mods: Headers back Billy Boat Exhaust, GripTec 2.65, 8.6 PowerBond Lower, LSX Innovations Solid Isolator, ID850's, NGK TR7IX's, Accel 9070CK Wires, Spectre CAI, SRI Ported Throttle Body, SRI Catch Can, NGK AFRM, 160* T-Stat, 0fx2gv Brick, Hard Line Delete W/3/4" Lines, FB 101 FMIC, Pierberg CWA50, Stoptech Drilled/Slotted Rotors, EBC Redstuff, Cut Stock Springs, Flat Bottom Steering Wheel
    2006 Black Raven STS-V (Traded In)
    Fully Modded: 459RWHP@5888rpm/451lbft@4696rpm

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    Quote Originally Posted by PGA2B View Post
    Check with RobZL1 as I remember a post where he talked about his struggles with this. BTW- I also am dealing with it in closed loop. If I add too much fuel or take too much out I can feel it so I have been trying to find the happy medium.
    So it's not just me....lol. Yeah, it happens in closed loop for me as well. I'll send him a PM and see if he has any ideas. Thanks for responding, I appreciate it as I'm at a total loss as to what to do/adjust. Doesn't happen during cold start/run as it's in open loop. I don't think my 02 sensors are bad as the car runs perfectly fine any other time. Is it possibly an issue with the ID850s? I contacted them and they seem to think it's a lean tip in issue...I disagree though. There has GOT to be a tuner out there that knows what to adjust.....i'm very mildly modified compared to alot of ctsv owners out there.
    Last edited by sgod1100; 10-09-2020 at 09:04 PM.

  12. #12
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    Regarding WOT / OL, you are on the right track with the MAF hump between 8k and 9k Hz. Just get it where you want it and smooth it a bit on both ends to blend it into the rest of the curve, then it will look much better and fueling will be where you want it. I've got a subtle hump in mine, too. I see you already have zeroed the prediction coefficients, so that will prevent further issues if you go back to blended. If you do go back to blended, go ahead and kill the VVE spikes. I found that even though it looks like you need them when you are running "VVE only," you really don't once it's blended again.

    Regarding CL cruising, the O2 sensors don't oscillate nearly enough or consistently enough when you are cruising at 2k+ RPM. How old are the sensors? I attached a couple of screenshots from some logs of my car. This was before I did the cam, so it would be close to your current mods. In these screenshots, the car had intake, headers, test pipes, id850s, 10" pulley, BAP. If you compare this to similar sections of your logs where you were cruising at 2000-2500 RPM, you'll see what I'm talking about.

    Here's one at idle (10 second zoom):
    idle_o2.jpg

    Here's one at cruise (10 second zoom):
    cruise_o2.jpg
    Last edited by RobZL1; 10-11-2020 at 03:48 PM.

  13. #13
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    Quote Originally Posted by RobZL1 View Post
    Regarding WOT / OL, you are on the right track with the MAF hump between 8k and 9k Hz. Just get it where you want it and smooth it a bit on both ends to blend it into the rest of the curve, then it will look much better and fueling will be where you want it. I've got a subtle hump in mine, too. I see you already have zeroed the prediction coefficients, so that will prevent further issues if you go back to blended. If you do go back to blended, go ahead and kill the VVE spikes. I found that even though it looks like you need them when you are running "VVE only," you really don't once it's blended again.

    Regarding CL cruising, the O2 sensors don't oscillate nearly enough or consistently enough when you are cruising at 2k+ RPM. How old are the sensors? I attached a couple of screenshots from some logs of my car. This was before I did the cam, so it would be close to your current mods. In these screenshots, the car had intake, headers, test pipes, id850s, 10" pulley, BAP. If you compare this to similar sections of your logs where you were cruising at 2000-2500 RPM, you'll see what I'm talking about.

    Here's one at idle (30 second zoom):
    idle_o2.jpg

    Here's one at cruise (30 second zoom):
    cruise_o2.jpg
    The sensors are the original ones to the car, so they are about 6 years old. I have also tried messing with the 02 sensor settings (proportional and integral) and still can feel the lean bump while passing through that 2400-2600 range. i've tried countless 02 sensor settings combinations with minimal improvements. I will get rid of the VVE spikes as you said

  14. #14
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    Rob are you sure you screenshot is 30s zoom? When I display 30 sec zoom mine looks drastically different. This was just a snap shot in the log that I originally posted
    30s zoom.JPG

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    Here is another log (not with the current tune that I attached), but shows those lean areas again. If you go to 10:05 you will see that the a/f ratio slowly briefly hits about 16.3. This is the surge that i'm feeling. Happens again at 10:09. Happens a few more times throughout the log as well. This condition happens anywhere from 50kpa to about 80ish kpa

    2400-3000 rpm lean.hpl

  16. #16
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    Yep, I'm a doofus. It was a 10s zoom. I edited my first post, and here are some snips that are ACTUALLY 30s zoom.

    1500-1800 rpm cruise (30 second zoom):

    1500-1800_cruise_30s.jpg

    600 rpm idle, stock cam (30 second zoom):

    600_idle_30s.jpg

    Yeah, yours look fine in that last snip you posted. A little peaky on the tops and bottoms, but not too bad. A little less proportional would put a little more curve at the tops and bottoms, but not a big deal at all.
    Last edited by RobZL1; 10-11-2020 at 03:53 PM.

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    Quote Originally Posted by sgod1100 View Post
    Here is another log (not with the current tune that I attached), but shows those lean areas again. If you go to 10:05 you will see that the a/f ratio slowly briefly hits about 16.3. This is the surge that i'm feeling. Happens again at 10:09. Happens a few more times throughout the log as well. This condition happens anywhere from 50kpa to about 80ish kpa

    2400-3000 rpm lean.hpl
    It looks like you just need to calm down your O2's. I'd start by dropping proportional limit, and killing proportional by a small percentage as well. Here's a snip of your shifts and my shifts (this is with cam, etc. from a few days ago, but it illustrates the slower O2 oscillations).

    sgod1100 shifts:

    sgod_snip.jpg

    RobZL1 shifts:

    RobZL1_shifts.png

    Try these O2 settings. All I changed was the Engine>Fuel>Oxygen Sensors page. I reduced the proportional "kick," changed the airflow modes to match the stock DOD settings, and also put some other stuff back to stock. Give it a try and see if it's any better. If it is better, it might also help to slow down the O2 changes a bit by adding 10-20% to the integral delay.

    sgod1100TryTheseO2Settings.hpt
    Last edited by RobZL1; 10-11-2020 at 04:32 PM. Reason: Add HPT file

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    Here is a log with limit lowered from 2 to 1.5 and proportional lowered 10%. It actually seems worse....sticks leaner longer than before and seems to hunt for stoic much more than before. Any other ideas Rob?

    limit and prop lowered.hpl

  19. #19
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    Honestly, that looks better to me. After you complete shifts, you're not getting that huge lean spike as you go through 2500 anymore. I see some odd spikes throughout the drive (some not at 2500), and they all seem to be related to the o2 swings being a little erratic in my opinion. I still think you just need to get the o2's to calm down a bit and oscillate more smoothly. That's the best I've got. If I duplicate the same runs through the gears up to about 3k rpm shifts in my car, the o2's oscillate very smoothly, especially above 2000, and the injectors and resulting lambda follow.

    I'd suggest trying the limit settings combined with the airflow mode settings in the file I posted.

    Here's a representative sample:

    Shifts with your new settings:

    sgodshifts.jpg

    vs

    Shifts in my car today:

    shifts.png

    I still think yours are getting better compared to the last pics above. It looks like the o2's are starting to try to form a pattern.
    Last edited by RobZL1; 10-12-2020 at 08:38 PM.

  20. #20
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    Quote Originally Posted by RobZL1 View Post
    Honestly, that looks better to me. After you complete shifts, you're not getting that huge lean spike as you go through 2500 anymore. I see some odd spikes throughout the drive (some not at 2500), and they all seem to be related to the o2 swings being a little erratic in my opinion. I still think you just need to get the o2's to calm down a bit and oscillate more smoothly. That's the best I've got. If I duplicate the same runs through the gears up to about 3k rpm shifts in my car, the o2's oscillate very smoothly, especially above 2000, and the injectors and resulting lambda follow.

    I'd suggest trying the limit settings combined with the airflow mode settings in the file I posted.

    Here's a representative sample:

    Shifts with your new settings:

    sgodshifts.jpg

    vs

    Shifts in my car today:

    shifts.png

    I still think yours are getting better compared to the last pics above. It looks like the o2's are starting to try to form a pattern.
    Thanks for taking the time to help me out, I appreciate it. I didn't realize that you posted some new o2 settings to try. I will give that a shot to see what happens