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Thread: Closed loop going lean??

  1. #21
    Here's the OL tune I'm using.

    2009 CTS-V Modified (VE Tuning)2.hpt

  2. #22
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    If I'm seeing correct data from your ngk lambda setup, it looks like lambda error is identical to fuel trim corrections. Are you sure you haven't just had this thing in open loop for so long that it's not just pulling in a lot from your evap system or something once finally put into closed loop? Or possibly just been fighting "rich after flash"?

    Your fuel trims are +30 to 40% with your lambda reading dang near 1 durring the fuel corrections telling me everything should be set up right. I don't like the O2 switching. Think it should be set a little quicker unless your just trying to drive it a little richer? Might want to fine tune your O2 settings in the tune for that. Otherwise I think you could tune this thing in closed loop and turn out good. Have you been setting your open loop correctors or multipliers to 1? If not that may also be what you've been fighting... Really think you could tune in closed loop giving it atleast 15 minutes of run time before datalogging in between tunes and you would be just fine. Maybe I missed something, but I think you would be OK...
    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

    ~Greg Huggins~
    Remote Tuning Available at gh[email protected]
    Mobile Tuning Available for North Georgia and WNC

  3. #23
    Quote Originally Posted by GHuggins View Post
    If I'm seeing correct data from your ngk lambda setup, it looks like lambda error is identical to fuel trim corrections. Are you sure you haven't just had this thing in open loop for so long that it's not just pulling in a lot from your evap system or something once finally put into closed loop? Or possibly just been fighting "rich after flash"?

    Your fuel trims are +30 to 40% with your lambda reading dang near 1 durring the fuel corrections telling me everything should be set up right. I don't like the O2 switching. Think it should be set a little quicker unless your just trying to drive it a little richer? Might want to fine tune your O2 settings in the tune for that. Otherwise I think you could tune this thing in closed loop and turn out good. Have you been setting your open loop correctors or multipliers to 1? If not that may also be what you've been fighting... Really think you could tune in closed loop giving it atleast 15 minutes of run time before datalogging in between tunes and you would be just fine. Maybe I missed something, but I think you would be OK...

    Shouldn't the lambda error after the fueling corrections be zero though? I mean shouldn't the fueling corrections result in a lambda 1 when the commanded lambda is 1?

  4. #24
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    Something else I noticed in the two datalogs. Your closed loop is with MAF, while the open is with SD? What are your fuel trims with closed loop and SD only?
    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

    ~Greg Huggins~
    Remote Tuning Available at gh[email protected]
    Mobile Tuning Available for North Georgia and WNC

  5. #25
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    Quote Originally Posted by wetcoast View Post
    Shouldn't the lambda error after the fueling corrections be zero though? I mean shouldn't the fueling corrections result in a lambda 1 when the commanded lambda is 1?
    Unless I was seeing incorrect data, which is possible with my datalogger using your scanned parameters, I was seeing a lambda 1 +/- .something with O2 switching which is normal for closed loop operation.
    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

    ~Greg Huggins~
    Remote Tuning Available at gh[email protected]
    Mobile Tuning Available for North Georgia and WNC

  6. #26
    Quote Originally Posted by GHuggins View Post
    Something else I noticed in the two datalogs. Your closed loop is with MAF, while the open is with SD? What are your fuel trims with closed loop and SD only?
    I'm pretty sure my tune in closed loop is hybrid. SD below 3000 rpm and MAF above 3000 rpm.

  7. #27
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    Quote Originally Posted by GHuggins View Post
    Something else I noticed in the two datalogs. Your closed loop is with MAF, while the open is with SD? What are your fuel trims with closed loop and SD only?
    That's where I was going with my questions...

    I assume you ran MAF only, tuned that, then did SD only, and tuned that prior to turning them both on?

    It would be interesting to see how the trims look in closed loop w/MAF only and closed loop SD only.

    I'd also add MAF g/sec and dynamic airflow g/sec to the items you are logging

    I also see you have it set to go into PE really, really easily.. yet commanded AFR is always 14.68 from what I've been able to see anyways. Any idea why?
    Last edited by schpenxel; 07-06-2015 at 12:00 PM.
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  8. #28
    Disconnect your MAF to tune SD mode that way you can't make a mistake, make sure your MAF fail is set to "MIL ON FIRST ERROR" under diagnostics. Once you're done your SD tuning in OL then switch to closed loop keep MAF unplugged and see.

    Once that's done tune your MAF by setting your dynamic air to use MAF after 200 RPM.

    Also, on a side note I never liked NGK AFX for VE tuning it seems to always be off from what 02's read so I use my Innovate LM1 to do the tunning. I have two NGK systems both read richer than stock 02's so they never match.

  9. #29
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    Don't want to disconnect MAF on the cts-v as it has iat built in. Just fail it normally and tune sd. If you really feel necessary even though it's not required or advised, you can carefully remove your MAF signal pin from the connector. BUT like stated, not necessary and a waste of time

    With your MAF in the equation even at 3000rpms it still referrences it up to that rpm for fuel trim corrections. Sounds and looks like "it" may not be dialed in...
    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

    ~Greg Huggins~
    Remote Tuning Available at gh[email protected]
    Mobile Tuning Available for North Georgia and WNC

  10. #30
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    Quote Originally Posted by schpenxel View Post
    That's where I was going with my questions...

    I assume you ran MAF only, tuned that, then did SD only, and tuned that prior to turning them both on?

    It would be interesting to see how the trims look in closed loop w/MAF only and closed loop SD only.

    I'd also add MAF g/sec and dynamic airflow g/sec to the items you are logging

    I also see you have it set to go into PE really, really easily.. yet commanded AFR is always 14.68 from what I've been able to see anyways. Any idea why?
    All except for PE delay (2000rpms) the PE is normal for the CTS-V's and ZL1's... This is why on really "wild" builds I go in and change some of the pedal settings for PE on these All though, I did not check in the datalog as to whether or not it was going into PE, so you might have found something there...
    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

    ~Greg Huggins~
    Remote Tuning Available at gh[email protected]
    Mobile Tuning Available for North Georgia and WNC

  11. #31
    Quote Originally Posted by schpenxel View Post
    That's where I was going with my questions...

    I assume you ran MAF only, tuned that, then did SD only, and tuned that prior to turning them both on?

    It would be interesting to see how the trims look in closed loop w/MAF only and closed loop SD only.

    I'd also add MAF g/sec and dynamic airflow g/sec to the items you are logging

    I also see you have it set to go into PE really, really easily.. yet commanded AFR is always 14.68 from what I've been able to see anyways. Any idea why?
    Yep, I ran MAF only and dialed that in and then SD dialed in.

    I could try MAF only and then SD only in closed loop but I'm not sure what I'd be looking for since it seems to work well for a while with both operating and then goes haywire.

    I'll add those PID's to my .cfg. I see I already have MAF g/sec.

    As far as I can see my PE mode enables early but results in a commanded lambda of 0.78 to start. See snapshot.

    Screenshot 2015-07-06 10.26.38.png

  12. #32
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    Ah, yeah I missed that spot

    You were at around 2psi of boost before it went into PE. Seems like all of the PE requirements were met in several other places but the commanded lambda never changed. Not sure if it's even an issue, just something I noticed.

    I also noticed that as soon as it switches from "normal" to "high speed" airflow mode (i.e. mixed mode to MAF only) the AFR changes quite a bit. It's around 0.80 lambda in normal then goes down to 0.70 lambda when it switches to MAF only. That makes me think the VE/MAF tables aren't right.

    Honestly.. I don't know. I'd try it closed loop, MAF only and see what you get. Make corrections to the MAF curve based on what you get, and see if the changes actually make a reasonable difference.
    Last edited by schpenxel; 07-06-2015 at 01:33 PM.
    Post a log and tune if you want help

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  13. #33
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    When you change one, it typically will require retuning the other This is why I like to do a final reMAF tune, before calling it good. Timing or anything will change fueling...
    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

    ~Greg Huggins~
    Remote Tuning Available at gh[email protected]
    Mobile Tuning Available for North Georgia and WNC

  14. #34
    Quote Originally Posted by schpenxel View Post
    Ah, yeah I missed that spot

    You were at around 2psi of boost before it went into PE. Seems like all of the PE requirements were met in several other places but the commanded lambda never changed. Not sure if it's even an issue, just something I noticed.

    I also noticed that as soon as it switches from "normal" to "high speed" airflow mode (i.e. mixed mode to MAF only) the AFR changes quite a bit. It's around 0.80 lambda in normal then goes down to 0.70 lambda when it switches to MAF only. That makes me think the VE/MAF tables aren't right.

    Honestly.. I don't know. I'd try it closed loop, MAF only and see what you get. Make corrections to the MAF curve based on what you get, and see if the changes actually make a reasonable difference.
    I just changed that .80 lambda location. In my VE tuning I didn't get into the higher load areas. I took that log in closed loop that I just posted and added about 16% to the 160-175 kPA and 2400-2800 rpm cells. This should fix that lean spot on WOT/PE.

    I will try closed loop MAF to see if it's the PI closed loop settings or just the VE table but I think it's the prior.

  15. #35
    Well I haven't had time to try running closed loop MAF only but I have been thinking. *oh no*

    I was wondering what impact moving the O2 sensors would have on the timing of the ECU seeing the change in exhaust gas composition.

    I found a rough way to calculate the exhaust flow at a given rpm and VE with this handy calculator:

    http://www.asia.donaldson.com/en/exh...ry/1053747.pdf

    Screenshot 2015-07-07 11.30.39.png

    Using some data from a log like this one:

    Screenshot 2015-07-07 11.39.44.png

    I calculated the exhaust flow in excel using the VVE table that's fairly accurate from the BC tool.

    I extrapolated the exhaust velocity in a single bank through 3" pipe.

    Screenshot 2015-07-07 11.40.06.png

    The results surprised me a bit but make it more understandable when I'm having closed loop difficulties.

    At the snapshot I referenced above, the exhaust gases would reach the O2 sensor relocated 12" further away (as it is in my case) from the head by about 2.5s at 1924 rpm!

    Obviously this would be a lot shorter time at higher rpm's but most cruising happens at the lower rpm ranges.

    I'm thinking that the closed loop integrator delay would need to be adjusted to reflect this change. I've already changed the entire table above by a factor of 1.3 but I'm feeling like this might need to be higher.

  16. #36
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    GHuggins knows a lot more about the integrator settings than me.. hopefully he can help
    Post a log and tune if you want help

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  17. #37
    Here's the excel spreadsheet if you want to see the math.

    Exhaust Gas Flow and time delay calculation.xlsx

  18. #38
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    A little more to it than just changing the numbers in your case since your running without cats. Header companies put the precat O2's as far forward as they can which means they're in the collector and only getting exhaust from two cylinders if your lucky. I highly recommend relocating them even further downstream. I'm attaching two pics showing where we relocate them to. Then from my own "playing" with these settings, I've been able to get the numbers pretty dang close by multiplying the O2 proportional "airflow" table by .9 and the integrator delay "airflow" table by 1.25. Shouldn't need a whole lot more than that...
    Attached Images Attached Images
    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

    ~Greg Huggins~
    Remote Tuning Available at gh[email protected]
    Mobile Tuning Available for North Georgia and WNC

  19. #39
    wow, way back!

  20. #40
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    You can't tell it from the pics, but those O2 boss's are also shaved 1/4" to allow full protrusion of the O2 sensor down into the exhaust stream... The O2's being relocated this way combined with the intrussion into the exhaust stream assures it gets a near 100% homogeneous exhaust gas referrence from all contributing cylinders on that bank.

    Modifying the proportional airflow settings seems to help just as much as the integrator delay settings. It also "seems" to make it to where you only have to "lightly" modify the integrator settings. Otherwise I think you would need to increase the integrator table by something like 1.5ish and even then I'm not sure you would get "all" benefits that I've personally seen from dialing these tables in...
    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

    ~Greg Huggins~
    Remote Tuning Available at gh[email protected]
    Mobile Tuning Available for North Georgia and WNC