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Thread: Tuning Notes by WeathermanShawn

  1. #101
    R.I.P Shawn, 1956-2011 WeathermanShawn's Avatar
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    Joecar has brought up an interesting point concerning B0120 RPM Threshold for Airflow Calculation and its role in the resulting LTFT correction(s). He has suggested that B0120 be set to 400 Rpms to insure that only the MAF airflow values are being applied. In the tune I am running, both MAF and VE Table Airflows are identical..so that issue would not have been as readily apparent.

    Thanks Joecar that is good feedback. I will do some more testing.
    Last edited by WeathermanShawn; February 10th, 2010 at 08:45 PM. Reason: Redundant..
    2002 Black Camaro Z-28 M6 Hardtop 11.0:1CR 425HP/410TQ SAE (400TQ@3500RPM)
    200cc Heads, 228/232 110+2 Cam, 1 3/4" LT's w/catts, GMMG, Koni Shocks, Hotchkis Springs, 35/21 Sways, 17" ZR1's, 3.90 Gears Roadrunner PCM LM-2 Serial Wideband
    EFILive Closed-Loop MAF/SD Hybrid Tune..


  2. #102
    Lifetime Member 5.7ute's Avatar
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    Quote Originally Posted by acomp917 View Post
    Separate thought,

    What does the GM system use for acceleration enrichment? I surely hope it is not an over rich VE then transition back to MAF. If that is the case, God help us. I know NO way to balance(tune) a transition/overfuel/transition back to required fuel situation. Without a rate of change table(easy to understand)ie. TPS/MAP(Tau, best).

    Transition being from one table to another one.

    Please, someone tell me there is an acceleration enrichment in there somewhere!!!


    S
    There is an acceleration enrichment algorithim which is apparently disabled if the maf is failed. Obviously wont be a problem here with Shawns method, but it could if you go to full time speed density.
    We do have access to some of the transient fuelling tables which will enable you to tune the wall wetting model (tau). If they are not available for your OS post a thread in the cax file section & one of us working on these should be able to set one up for you.
    The Tremor at AIR

  3. #103
    Lifetime Member Steve Bryant's Avatar
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    Shawn,
    I think that Joecar has a point here. I haven't wanted to rain on your parade, because you may really be on to to something and I could be wrong.

    Here's what I think may be going on. As long as the MAF is fairly close to being calibrated and as long as the VE table is fairly close, it won't take much short or long term fuel trim to keep things at stoic. Further, if PE is set up right that will be fine too.

    The PCM primarily is biased to reference the MAF (unless it is disabled). Even though you haven't done anything yet to exclude speed density/VE (like setting {B0120} to a very low value like 400 RPMs); you've calibrated your MAF to stoic using the LTFT corrections to alter the fueling equation values represented by the MAF table in {B5001}. Since the car mostly is running on your accurized MAF, it should run well unless the VE is really out of whack and even then only during transients like acceleration/deceleration.

    This is what I think is happening . . . but I could be wrong. Whether I'm right or wrong, you've made me rethink a lot of things and I'm glad. I haven't fooled around with tuning much for at least four years. Now, I'm ready to come back, get rid of the rust on my brain and learn a lot more. I had really become saturated and I had way too much else going on in my life. Your thread and tutorial have helped inspire me to get more involved and I thank you for that.

    All my best,

    Steve

  4. #104
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    http://www.smokinvette.com/corvettef...020#post392020

    Shawn, this sounds like the handholding/spoonfeeding you're after.

  5. #105
    R.I.P Shawn, 1956-2011 WeathermanShawn's Avatar
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    Quote Originally Posted by Steve Bryant View Post

    The PCM primarily is biased to reference the MAF (unless it is disabled).

    Steve
    Steve, I think Joecar is absolutely correct about B0120 and its influence on LTFT's and ultimately how it affects airflow calculations. And I totally agree with your point. Here is ultimately the question. How much does the MAF control airflow calculations (and LTFT's) when it is not disabled? Its hard to get a quantified answer. Does it just look for a correction factor (VE) and if it is an acceptable limit, ignore it?

    What is interesting is that the stock VE Tables are incredibly 'rich'. If your MAF fails (and they do), those values of airflow equate to a lot of additional fueling. And you are right, Trims may be totally capable of handling even a 'richer (higher airflow values) VE Table. Here is what we probably do agree on. The CALC.VE method does allow a MAF-enabled Closed-Loop tune to covert cylinder airflow into its dynamic airflow equivalent. So, they are identical. Now, here is the ultimate question. Do you want them identical? Is is better to have a 'richer' VE Table for transient fueling or MAF failure?

    Quote Originally Posted by redhardsupra View Post
    http://www.smokinvette.com/corvettef...020#post392020

    Shawn, this sounds like the handholding/spoonfeeding you're after.
    Actually that sounds like a good idea. Have you taken it?

    It might help you to learn how to teach others the GMVE method of tuning....
    Last edited by WeathermanShawn; February 9th, 2010 at 09:20 AM. Reason: Redundant, Combined Thread..
    2002 Black Camaro Z-28 M6 Hardtop 11.0:1CR 425HP/410TQ SAE (400TQ@3500RPM)
    200cc Heads, 228/232 110+2 Cam, 1 3/4" LT's w/catts, GMMG, Koni Shocks, Hotchkis Springs, 35/21 Sways, 17" ZR1's, 3.90 Gears Roadrunner PCM LM-2 Serial Wideband
    EFILive Closed-Loop MAF/SD Hybrid Tune..


  6. #106
    R.I.P Shawn, 1956-2011 WeathermanShawn's Avatar
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    I hope to have the final version of this 'Tutorial' finished no later than February 15, 2010. The goal is to a tuner who is utilizing the MAF and staying Closed-Loop to properly and accurately construct a VE Table, MAF Calibration, and Trim simultaneously. Most can be accomplished on one tune run.

    There may be a few minor additions. B0120 (RPM Threshold for Airflow Calculation) may be initially changed to 400 RPM's. B0120 has absolutely no influence on the actual CALC.VE values. That value is calculated totally from MAF, IAT, and RPM and is not dependent on B0120. The modification however may prevent any inadvertent stock VE values from influencing the initial LTFT correction, which is used in later steps.

    Lastly, 5.7ute submitted an excellent suggestion for a new Calculated PID: CALC.NEW_VE={CALC.VE}*{CALC.LTFTBEN} which can then be pasted directly into the B0101 VE Table. That will save even another step. Separately 5.7ute has also graciously volunteered to evaluate my logs and tunes using several different parameters. Hopefully with time we can work a more refined CALC.VE formula that includes an ECT value.

    If anybody sees anything major, please PM me or post constructively.
    Last edited by WeathermanShawn; February 10th, 2010 at 08:47 PM. Reason: Grammer.
    2002 Black Camaro Z-28 M6 Hardtop 11.0:1CR 425HP/410TQ SAE (400TQ@3500RPM)
    200cc Heads, 228/232 110+2 Cam, 1 3/4" LT's w/catts, GMMG, Koni Shocks, Hotchkis Springs, 35/21 Sways, 17" ZR1's, 3.90 Gears Roadrunner PCM LM-2 Serial Wideband
    EFILive Closed-Loop MAF/SD Hybrid Tune..


  7. #107
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    The normal operation is MAF/SD hybrid. It seems like you're tuning only the MAF table. If you go back to the standard operation, MAF and SD airflow values are compared to each other for a 'sanity check.' If they don't agree (and they won't, since you're ignoring SD component), the ECU will probably fall back on it's 'backup' mode, which is SD. Which you did not tune. So as a results of your t00nin' you will end up running in a mode that haven't been touched.

    Do you still think it's a good idea?


    PS. here's an interesting observation about the MAF/SD collaboration:
    http://www.hptuners.com/forum/showpo...8&postcount=16
    Last edited by redhardsupra; February 10th, 2010 at 04:31 AM. Reason: added the link

  8. #108
    R.I.P Shawn, 1956-2011 WeathermanShawn's Avatar
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    Quote Originally Posted by redhardsupra View Post
    The normal operation is MAF/SD hybrid. It seems like you're tuning only the MAF table. If you go back to the standard operation, MAF and SD airflow values are compared to each other for a 'sanity check.' If they don't agree (and they won't, since you're ignoring SD component), the ECU will probably fall back on it's 'backup' mode, which is SD. Which you did not tune. So as a results of your t00nin' you will end up running in a mode that haven't been touched.

    Do you still think it's a good idea?
    The CALC.VE formula is calculating airflow independently of the MAF/SD 'sanity check'. You can verify this by logging the CLYAIR.DMA and DYNCYLAIR.DMA. With B0120 at 400 RPM's, it will never fail into a SD backup mode. Your CALC.VE will be the same whether you choose 400 or 4000 RPM's for your B0120 Threshold.

    The question of the LTFT correction and B0120 has been raised. But that has absolutely no influence on the CALC.VE airflow computation. The question is B0120 influence on LTFT's.

    I will reiterate. The CALC.VE formula does not require a B0120 change. To run in Closed-Loop you simply need your LTFTBEN vs MAF Frequency to be 1.00 +/- 2%.

    Whether you accomplish that with B0120 at 400 or 4000 RPM's is not that relevant. B0120 influence on the LTFT correction is the issue. Has not been with my tune, but I got mine down in two runs.
    Last edited by WeathermanShawn; February 10th, 2010 at 08:48 PM. Reason: Grammer
    2002 Black Camaro Z-28 M6 Hardtop 11.0:1CR 425HP/410TQ SAE (400TQ@3500RPM)
    200cc Heads, 228/232 110+2 Cam, 1 3/4" LT's w/catts, GMMG, Koni Shocks, Hotchkis Springs, 35/21 Sways, 17" ZR1's, 3.90 Gears Roadrunner PCM LM-2 Serial Wideband
    EFILive Closed-Loop MAF/SD Hybrid Tune..


  9. #109
    Joe (Moderator) joecar's Avatar
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    B0120 is set to 400 to restrict the source (airmass calculation) for LTFT-correction-to-MAF to be the MAF only (and not switching between MAF and VE).

  10. #110
    R.I.P Shawn, 1956-2011 WeathermanShawn's Avatar
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    Sometimes it is quite difficult to know in a MAF-enabled car how much Trim function is coming from the VE Table and how much the MAF.

    I did two log runs this morning. One with my regular VE Table, the other with a stock 2002 Camaro VE Table. I did reset the Trims prior to switching to the stock VE Table. I left B0120 at 4000 RPM's in each case.

    By, the way I would never advised doing that. I could barely start the car (very rich). But, the CALC.VE % were virtually identical. CYLAIR.DMA and DYNCYLAIR.DMA were identical in run one, but very disproportionate in run two.

    Trims were affected to some degree, but interestedly it still seemed like the MAF was doing the majority of the Trim function (except for idle). I did not make any MAF adjustments between runs. Is it possible that the VE Table makes an airflow correction fueling wise, but the actual LTFT function is controlled by the MAF?
    Last edited by WeathermanShawn; February 10th, 2010 at 08:49 PM. Reason: revised
    2002 Black Camaro Z-28 M6 Hardtop 11.0:1CR 425HP/410TQ SAE (400TQ@3500RPM)
    200cc Heads, 228/232 110+2 Cam, 1 3/4" LT's w/catts, GMMG, Koni Shocks, Hotchkis Springs, 35/21 Sways, 17" ZR1's, 3.90 Gears Roadrunner PCM LM-2 Serial Wideband
    EFILive Closed-Loop MAF/SD Hybrid Tune..


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