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Thread: Throttle Cracker Tuning Question {B4309}

  1. #81
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    Quote Originally Posted by pinstripebob View Post
    With the headlights on, it seems like RPM comes back down nicely, hangs for a moment above idle speed, dips, then comes back up to idle speed.
    I'm making some more adjustments for this, but like I said previously... without logging all the airflow pids it can be difficult to get a really nice return to idle.

    Quote Originally Posted by pinstripebob View Post
    I am kind of curious about the times when my commanded AFR is 15.46:1. It looks like when I'm stopped and idling, after a moment the engine commands 15.46:1 for about 4 seconds then goes back to 14.68:1. FUELSYS-A is in OL-Drive. Out of curiosity, what part of the tune is making this happen? CL mode is 8 the whole time I'm stopped, so that isn't changing.
    The PCM does a whole bunch of diagnostic tests while you're driving... this is one of those tests. It will only ever do it at idle. I'm guessing that GM figured that sending you lean at idle was the safest time to do it. Unfortunately, we have no way of disabling this test. It's something you just have to live with.

    Quote Originally Posted by pinstripebob View Post
    Like I mentioned above, overall it seems to behave pretty darn well under normal driving conditions.
    Yeah, your last log doesn't look all that bad. We'll still do some more changes and see if we can clean it up a bit more.
    Last edited by statesman; April 19th, 2019 at 02:33 PM.

  2. #82
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    Quote Originally Posted by statesman View Post
    I'm making some more adjustments for this, but like I said previously... without logging all the airflow pids it can be difficult to get a really nice return to idle.
    Yep, I remember you mentioning that. I got a few blips at the end of today's log and the modifications you made without logging all the right PIDs made a big difference for the better.
    Quote Originally Posted by statesman View Post
    The PCM does a whole bunch of diagnostic tests while you're driving... this is one of those tests. It will only ever do it at idle. I'm guessing that GM figured that sending you lean at idle was the safest time to do it. Unfortunately, we have no way of disabling this test. It's something you just have to live with.
    No worries, I was just curious. I can't tell when the test is performed, although it did catch my eye when I looked through the log. My wife's Cruze performs some test that's probably the same, it's definitely noticeable in her car.

    I got a new log with the Mod14 tune, attached at the end of this post. I have an analog gauge on my dash hooked up to my WO2 sensor, I noticed that transient fuel when going from 0 throttle to some throttle seemed to be in very good shape. Very little needle movement, and it snapped back to stoich very quickly.

    In some areas the bucking has gone away a bit more, there are a few notable spots as follows:
    Frames 233-434
    Frames 1689-1780
    Frames 9549-9585
    Frames 10409-10449

    I received a phone call around frame 11,320 and shut the engine off for a minute before turning it back on. I got some throttle blips after waiting 30ish seconds post-restart.

    Throttle blip, no headlights:
    Frames 11634-11665
    Frames 11670-11714

    Throttle blip, headlights/heater:
    Frames 11752-11785
    Frames 11791-11824

    Let me know what you think, or if there's a specific test I can do. If you need me to change my driving style or try getting a specific type of driving I can do that as well. Thank you!

    Log:
    GTO April 4 2019 IBC to home.efi

  3. #83
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    Your return to idle looks decent now but I'm making a small adjustment, so you'll still have to do the throttle blips at the end of the log.

    Transients are a bugger to get exactly right. I think your transients now are in better shape overall than they were when we started, so we might just leave them the way they are now.

    This update is mainly focused on the bucking issue.

    Log like you've been logging.
    Last edited by statesman; April 19th, 2019 at 02:34 PM.

  4. #84
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    Good deal

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    Quote Originally Posted by joecar View Post
    Good deal
    Hey joecar, nice of you to drop in.

    Yeah, I think this is a good deal for bob... he's getting a decent tune at no cost.

  6. #86
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    Haha yeah I really appreciate the help on this! It's made a huge difference with my car, and me being able to see all the changes you make has really helped me learn! I've been doing a bunch of reading as well, it's freakin' awesome!

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    Flashed the tune, did some driving, and got a log. Overall things feel pretty darn good! The only notable, repeatable bucking during normal driving is low speed, low throttle cruising in 4th gear. A good example in the log to see this is frames 5,221-5,328.

    Bucking during deceleration has gotten a lot better. Sometimes it will buck around 1,000-1,100 RPM, but it isn't often. There will normally be a little bucking under 1,000 RPM. It's almost hard to find in the log, frames 10,961-10,984 are an example.

    There was some bucking in frames 4,613-4,885 as well, not terrible but it was there.

    I did some throttle blips at the end of the log as follows:
    Blip 1, no headlights, frames 15,528-15,550
    Blip 2, no headlights, frames 15,551-15,589
    Blip 3, headlights/heater, frames 15,596-15,622
    Blip 4, headlights/heater, frames 15,627-15,670

    Let me know what you think, or if there's anything you need me to try. Again I really appreciate the help! Thanks!

    Log:
    GTO April 9 2019 IBC to home.efi

  8. #88
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    We're almost there.

    With this update, I'd like you to do a log like you normally do, then do a calc.VET and update your MAF and VE tables and then do another log. Do the throttle blips at the end of the log like you've been doing.

    Post your updated tune file with the two logs.
    Last edited by statesman; April 19th, 2019 at 02:35 PM.

  9. #89
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    Awesome! I did as you said, I did a log, updated my MAF and VE tables, and got a second log. I used the PIDs in the CALC.VET tutorial to stay at 24 channels for the VE log, but I think I got some good data and got a decent update on the two tables.

    Overall driveability is still improving and seems to be in pretty good shape. There's a little bit of bucking around 25-30mph (40-48kmh) but that's the worst. A couple examples of this are below:

    Light throttle bucking:
    Frames 4527-4565
    Frames 5004-5085

    There are some other spots in the log where you can see a bit of surging, but it's very low amplitude and overall the car's driving well. I did some throttle blips at the end of the log as well as follows:

    Blip #1, no headlights: Frames 13,104-13,134
    Blip #2, no headlights: Frames 13,138-13,171
    Blip #3, headlights: Frames 13,213-13,249
    Blip #4, headlights: Frames 13,267-13,306
    Blip #5, headlights: Frames 13,315-13,344

    Let me know what you think, hopefully I didn't do too much damage with those tables! Thanks!

    VE log: GTO April 12 2019 VE log.efi

    Latest log: GTO April 15 2019 IBC to home.efi
    Last edited by pinstripebob; April 16th, 2019 at 07:58 AM.

  10. #90
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    That occasional minor surging is going to be difficult to totally cure, but we haven't got much bucking left now which is good. Let's see how we go with this update.

    Log like you've been logging.
    Last edited by statesman; April 22nd, 2019 at 07:08 PM.

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