resident twEECer guru...

Discussion in 'Fox 5.0 Mustang Tech' started by ddonaca351, Sep 11, 2009.


  1. ddonaca351

    ddonaca351 Active Member

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    Hey all,

    Just starting to get back into things after about 18 months away from stang'dom...

    Is it true that there is/are now tweecer gurus on the site here?

    Reason I ask is before I went away from the stang obsession, I fought a deceleration idle issue on my 90 for about a year and could never get it worked out.

    (most mods in sig, basically a 306 24# CnL h/c/i car, A9L)

    On decel if I was steady state throtle or light acceleration and went clutch in, it would drop to an idle just fine as I came to a stop. If I was actually throtle full closed on decel and went clutch in, the damn thing would die upon coming to a stop. If I jacked the IAC decay rate way up, it would hold, but of course then I would get the dreaded hanging idle problem... :mad:

    Any ideas, or at least anyone willing to help me think through it, if I get off my butt and get the car driveable again? :shrug:

    If we have an "expert" ( uh-oh, he used the E word... ) to pester with questions, I might actually try to take up the battle again.

    (I still have the car, but it's sat for over a year... yeah I know, I have to drop the tank, flush the lines, etc... don't remind me)

    Thanks,

    Dave
  2. strtrcr50

    strtrcr50 New Member

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    VRIStang is about the best on here I think. I need to think about yours and see if anything comes to mind. Just out of curiosity, do you have another mass air meter you could swap out just to make a few test runs?


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  3. ddonaca351

    ddonaca351 Active Member

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    No I don't have another MAF.

    ( I did clean the maf wire... several times, in case it was coated with crud but no change )

    I also-
    cleaned the IAC valve, multiple times
    reset the idle, multiple times
    reloaded and retuned the MAF curve twice
    replaced the IAC solenoid
    removed and reinstalled the TB (70mm acufab) looking for vac leak
    removed and reinstalled the upper intake, twice looking for vac leak
    disconnected and reconnected the 10 pins (3-4 times)
    had the injectors flushed (was running 19s with sky high fuel psi)
    replaced the injectors with 24s (lowered fuel psi to reasonable levels... 38-40psi at idle if memory serves)
    reloaded the base tune and retuned the entire program from scratch (fuel, timing, everything...)

    I have run with adaptive enabled and adaptive disabled both, it still does it.

    Again any help would be greatly appreciated.

    I love my ride, I really do... but it just got to where I couldn't bear the thought, of another weekend spent fighting with it.... ya know.

    Thanks fellas,
    Dave
  4. strtrcr50

    strtrcr50 New Member

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    Only reason I asked is because I had a horrendous time trying to get a C&L consistantly dialed in. Right now, I'm back to stock until the new motor goes in with the 42's and proflow maf. What computer are you running? Is it a x3z or do you have the fuel shutoff on decel turned on with an a9l?
  5. vristang

    vristang Advanced Member

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    I never had any issues with decel idle speed like that, so I'm probably not much help on this one LOL

    May try running an X3Z bin as opposed to starting with an A9L bin. The X3Z works with decel conditions differently, so it may be a quick way to check some things out.

    Are you getting any diagnostic codes?
    Checked for vac leaks?

    A datalog taken when the car is dying may shed some light on things for you?
  6. ddonaca351

    ddonaca351 Active Member

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    no codes

    vac leak? see above... checked and rechecked multiple times.

    x3z sigh, oh goodie... reprogram everything from scratch - again. :nonono: :mad: :jaw:

    I mean damn guys... thats like 6 weeks worth of work to build a complete tune. ( tune, datalog, download & analyze logs, crunch numbers, make a change, repeat the sequence... about 50-60 times ) Frack.

    I dont supoze anybody has a TF Track Heat top end on a 306 (TF stage 2 cam if poss...it's similar to my Lunati), and would be willing to share their numbers for comparrisons sake?
  7. strtrcr50

    strtrcr50 New Member

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    Last thing that immediately comes to mind is people who do a mass air swap into a speed density car have similar problems because they don't have the speed sensor hooked up. Did you try datalogging the mph and see if it changes?
  8. vristang

    vristang Advanced Member

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    I don't think you have a tuning issue... After reading through this again, it sounds more like standard efi troubleshooting will help you more than messing with the tweecer... at this point anyway...

    Are you getting any Diagnostic Trouble Codes?
  9. ddonaca351

    ddonaca351 Active Member

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    No trouble codes...

    And I was a ASE cert tech in f.i. & eimssions cont. for several years before going in the military, so if it's basic troubleshooting... I'm stumped.
    ( my kingdom for a Sun engine analyzer :rlaugh: :D )

    Like I said, I fought this same problem for well over a year (before I finally gave up).

    So what would you suggest I look at for a possible cause?
    :shrug:

    Remember now it ONLY does it on closed throtle deceleration to clutch in, when you come to a stop it dies.
    Steady state throtle or accelerating, go clutch in to a stop and it will idle fine.

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