Strange sound behind the dash at high rpm

Discussion in '96-04 - 2V Specific' started by Adam Vinnicombe, Nov 19, 2020.

  1. Adam Vinnicombe

    Adam Vinnicombe Active Member

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    To all the clever people out there I need help plus I have a problem with the new edge again
    This is going to be hard to explain but here I go.
    When driving the car like a normal person all is good but if I drive it like a mustang should be driven and take the rpm up high say like to 6,000 rpm and then take my foot of the accelerator but leave the car in gear there has been a strange sucking sound coming from behind the dash and it would continue until the rpms fell down to around 2,500 ish. Then today the sound changed. The only way I can describe it now is that it sounds like the air blower bearing is dying. It’s hard to describe but it’s a rotating, grinding sound it really does sound like the hot air blower in my good of nova just before it finally stopped. Anyway I don’t think it is the blower motor cause no matter what speed I have that on or totally turned off the sound is still there but only if I take the rpm up high (in any gear) and come of the accelerator with the car in gear. Like I said it will disappear once the rpm drops to 2500 or a quick blip on the clutch and it goes.
    Any ideas ?
    It doesn’t sound like it’s coming from the NEW engine but behind the dash.
    Thanks for your help all and sorry if this post is a little long
     
  2. evilcw311

    evilcw311 Most Evil Member! SN95 Supporter

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    Check all the vacuum lines under the hood and then check them inside the center dash where the climate control is. I’ve seen the diverter control start to go bad and make that same sound. Your hearing it under vacuum loads.


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  3. Adam Vinnicombe

    Adam Vinnicombe Active Member

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    Strange you should say that because the air position switch has just failed. It only works on face mode, as soon as you select any other mode it defaults to the window screen
     
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  4. evilcw311

    evilcw311 Most Evil Member! SN95 Supporter

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    Sounds like you now know where to start liking for sure.

    The vacuum inlet is on the firewall towards the passenger side. It’s a super small hard plastic line. Start there and then if it’s good pull the climate control cluster.


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  5. white95

    white95 Apex Junky Admin

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    Any resolution?
     
  6. Adam Vinnicombe

    Adam Vinnicombe Active Member

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    All sorted, the blue vacuum Milne behind the dash had split. So I replaced it yesterday and the hissing sound has stopped and now the fresh air director dial has started working again. I can now have hot air blowing at my feet again .
     
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  7. 96blak54

    96blak54 Legend

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    evilcw311 is one sharp dood! I would have never thought of a vacuum leak.
     
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  8. Werecow

    Werecow Well-Known Member

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    Vacuum leaks can be the bane of trouble shooting and the easiest to overlook.. The best trouble shooting tool and engine diagnosis guage I own is an old vacuum guage.. @evilcw311 is pretty smart on the troubleshooting fo sho!!
     
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  9. evilcw311

    evilcw311 Most Evil Member! SN95 Supporter

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    My vacuum leak testing tool of choice is a nice stogie!!!!!


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  10. Adam Vinnicombe

    Adam Vinnicombe Active Member

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    If I’ve been having his vacuum leak would that off effect my LTFT and STFT?
    Would this of cause the car to run lean enough to cause any noticeable issues ?
     
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  11. evilcw311

    evilcw311 Most Evil Member! SN95 Supporter

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    Ltft and stft???????

    And yes, vacuum leaks can cause you to run lean as it’s sucking in unmetered air.


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  12. white95

    white95 Apex Junky Admin

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    Do you even Mustang bro? That means long and short term fuel trim.
     
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  13. evilcw311

    evilcw311 Most Evil Member! SN95 Supporter

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    Bruh I’ve been wrenching since I was 14, 27 years. Sorry if I don’t have every lil acronym memorized. Had to have a customer tell me what fomo was the other day when he wanted to spend some serious cash. When he told me I was like “you make well over $900k a year and your way of telling me how badly you want something is saying Fomo bruh.......”

    Why can’t people just use words anymore.......


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  14. Werecow

    Werecow Well-Known Member

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    IKR???
     
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  15. ttocs

    ttocs Post Whore

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    lol
     
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  16. 96blak54

    96blak54 Legend

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    LMAO SMH Dis sum mofo funny chit
     
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  17. white95

    white95 Apex Junky Admin

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    Totes G
     
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  18. Adam Vinnicombe

    Adam Vinnicombe Active Member

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    Hi all so far everything seems to be working great now I’ve fixed that vacuum line but I am a little confused about the LTFT and STFT. Now before I fixed the vacuum line the LTFT at idle was at +5 on both banks and STFT was floating between -2 to +5 on both banks but now the LTFT has gone to -8 on bank one with a STFT of -2 to +2 and bank twos LTFT is at -3 with a floating STFT of -2 to +3.
    All this is at idle and the STFT are more in the negatives than positives. What is this tell me ?
    Is this all because of that vacuum leak or is something else going wrong?
     
  19. Frank.JD.Perez

    Frank.JD.Perez Legend

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    @evilcw311 has no idea what he's talking about, it was definitely a chipmunk fighting a mongoose behind the dash
     
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  20. evilcw311

    evilcw311 Most Evil Member! SN95 Supporter

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    Its a chipmunk and a Squirel. Get it right.


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