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Thread: Dashpot Tuning Questions

  1. #1

    Dashpot Tuning Questions

    Hi guys. I was wondering if anyone has messed with the dashpot tables under idle to change how the car reacts when you lift off the throttle. I've already removed some airflow from Dashpot Preposition and Minimum and added some to Dashpot Decay. I'm wondering how aggressive I can go before the car stalls when i put in the clutch. I've considered maxing out Dashpot Decay and zeroing out Dashpot Preposition thinking that it will go to the minimum airflow as soon as possible. Along the same lines i'm not really sure how the Dashpot Min (4th gear) tables affect things. i've read that on the EEC stuff it was to prevent clutch stalls on manual cars but was curious if that was the case on the newer cars and if so how it worked. Thank you for any insight.

  2. #2
    HPT Employee Eric@HPTuners's Avatar
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    The logic works the same as before. I have never tried or wanted to try maximizing the decay rate, but I suppose you could try. I think you will find that you need some decay to prevent the stalling. I normally make 10% adjustments to the decay rate each time until I get it to feel the way the customer wants.
    Eric Brooks
    HP Tuners, LLC

  3. #3
    I'll have to keep playing with it. It seems like i'm only getting a noticeable change by modifying Dashpot Minimum so I was thinking it was hitting the minimum number. Could you give me some more details on the Dashpot Minimum 4th gear tables? All the information I could find was that it had something to do with clutch stalls. Does it use this table when the clutch is in instead of Dashpot Minimum? If so are there conditions where 4th Gear no decel will be used? Both are the same in my tune. Thanks for the info!

  4. #4
    HPT Employee Eric@HPTuners's Avatar
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    When I have some time, I will try to write up some information on how they are all used.
    Eric Brooks
    HP Tuners, LLC

  5. #5
    Just to follow up. I tried it today. Maxed out "Idle Dashpot Decay" to all 16.00s and zeroed out "Idle Dashpot Preposition" It actually only made a very small difference. I ended up also zeroing out "Idle Dashpot Minimum", "Idle Dashpot Min. 4th Gear", and "Idle Dashpot Min. 4th Gear (no decel). This made the RPMs dive more aggressively. Still didn't have any trouble with stalling on clutch in. I actually still wanted it more aggressive so my friend suggested also making DFCO come in as quickly as possible. This made the biggest difference as the car cuts fuel now as the RPMs are diving.

  6. #6
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    I'd like to have a good explanation of how the dashpot, idle min, idle prep, airflow at idle/park work. I have two stock factory 09 tunes for turbo FG auto and they use very different figures for the same engine in the same year. It would be good to know what other tables are influenece by the above tables.
    Last edited by turbotrana; 04-26-2014 at 07:08 PM.

  7. #7
    Quote Originally Posted by Exley View Post
    Just to follow up. I tried it today. Maxed out "Idle Dashpot Decay" to all 16.00s and zeroed out "Idle Dashpot Preposition" It actually only made a very small difference. I ended up also zeroing out "Idle Dashpot Minimum", "Idle Dashpot Min. 4th Gear", and "Idle Dashpot Min. 4th Gear (no decel). This made the RPMs dive more aggressively. Still didn't have any trouble with stalling on clutch in. I actually still wanted it more aggressive so my friend suggested also making DFCO come in as quickly as possible. This made the biggest difference as the car cuts fuel now as the RPMs are diving.

    I was just going over my tune and the stock tune on my 2013 GT has those same values. My Dashpot Decay is 15.99 across the board and everything else is zeroed out.

    Does this mean the only way to make it more aggressive is to have DFCO come in quicker?
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  8. #8
    HPT Employee Eric@HPTuners's Avatar
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    These cars use Torque Based decal and the Dashpot stuff does nothing unless you disable the torque based decel.
    Eric Brooks
    HP Tuners, LLC

  9. #9
    Quote Originally Posted by Gremlin85 View Post
    I was just going over my tune and the stock tune on my 2013 GT has those same values. My Dashpot Decay is 15.99 across the board and everything else is zeroed out.

    Does this mean the only way to make it more aggressive is to have DFCO come in quicker?
    Yes sorry, I didn't specify in my first post. My car is an 05-09 with the 3v 4.6

  10. #10
    Advanced Tuner 68Camaro's Avatar
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    These cars use Torque Based decal and the Dashpot stuff does nothing unless you disable the torque based decel.
    I know this is an old thread but can anybody tell me where to find the torque based decel table or on/off (disable)?
    Thanks

  11. #11
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    Engine>Idle>Airflow

  12. #12
    Advanced Tuner 68Camaro's Avatar
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    Engine>Idle>Airflow
    Thanks for the response but this only leads to idle airflow and dashpot tables which I already found.

    My initial problem was after revving the engine it would just fall down and die. I wanted to use the dashpot tables to catch the engine and settle back into idle. I did find the torque switches in the torque management tables but disabling these switches caused the engine to hang high idle and I still was unable to use the dashpot settings to catch the engine and settle back into a controlled idle.

    I re-enabled the torque switches and then found the magic table to catch the engine and settle back into a controlled idle in the torque management section. I searched high and low on here and never found anyone else sharing the information and even couldn't find anything searching Google - must be highly guarded info
    Last edited by 68Camaro; 11-17-2015 at 07:06 PM.

  13. #13
    Senior Tuner Higgs Boson's Avatar
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    I doubt it's highly guarded. HPT hasn't been in the Ford game that long vs GM stuff.

    How about this. MAYBE you are the first to deal with this and......you haven't posted what you did to fix it so I guess that you are part of the problem, no?

    ;-)

  14. #14
    Advanced Tuner 68Camaro's Avatar
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    lol - just wanted to see if anyone was actually interested before I posted up the fix. The platform I am working with is a 2010 F150 5.4 with a Green Oak pcm (if it matters to any of you). The magic table that fixed the idle falling after a rev - Engine>Torque Management>Friction Torque

    raising the numbers in the 100 and 180 (ect) rows worked like magic! I had to raise the numbers substantially (the 180 row had zero's factory and now they are around 30 in my tune).

  15. #15
    Senior Tuner Higgs Boson's Avatar
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    Very nice, thank you!

  16. #16
    Advanced Tuner GapRider's Avatar
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    Quote Originally Posted by 68Camaro View Post
    lol - just wanted to see if anyone was actually interested before I posted up the fix. The platform I am working with is a 2010 F150 5.4 with a Green Oak pcm (if it matters to any of you). The magic table that fixed the idle falling after a rev - Engine>Torque Management>Friction Torque raising the numbers in the 100 and 180 (ect) rows worked like magic! I had to raise the numbers substantially (the 180 row had zero's factory and now they are around 30 in my tune).
    Did you have torque based decel disabled?
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  17. #17
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    Quote Originally Posted by Eric@HPTuners View Post
    When I have some time, I will try to write up some information on how they are all used.
    Did you ever make that write up? My 2013 GT500 needs a little fine tuning in that area.

  18. #18
    Advanced Tuner GapRider's Avatar
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    The 2D graph doesn't match the table view for Idle Dashpot Clip Multiplier vs ECT.

    Also, are the units really in lbm? I thought a multiplier would be unitless but I am quite a rookie at this stuff.

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  19. #19
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    In case guys are looking for this switch, in the 3.7s I work on, it is under Engine:Idle:General
    Torque Decel Switch to Disable and you'll have your Dashpot functionality at your command
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