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Power 'shutoff' before end of 1/4 mile

Discussion in '5.0L Coyote V8 Engine Modification/Discussion' started by Darth Racer, May 27, 2018.

  1. Darth Racer

    Darth Racer Member Established Member

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    I've got a problem others may have had, but I'll post my issue. I have the Roush phase II SC dealer installed on a base '16 Mustang GT. It was part of the '$39,999' promotion a couple of years ago. It's an M6. 3.73 gears. I have several suspension upgrades and full length, long tube headers with X-pipe. I use MT drag radials. I have had it tuned at a local speed shop. Dyno numbers were about 600 to the wheels at 6800 RPM. 'Officially', this is the 727 HP package.

    I do have an SCT tuner. And, I have used it. The issue is that at about the 1100-1200 ft. mark, power is completely shut down. I adjusted max allowable RPM range thru the tuner to 7500, but it still shut down. The problem could be the 3.73s? In 4th gear I get to about 7200 RPM....around ~ 1100 ft. mark....and then power is pulled from the engine. I do have the advance-trac disabled when I run. So, the track nannies shouldn't be the issue.

    I'm thinking of setting max allowable RPM to 8,000 to see if that fixes the problem, but it could be something else? A sensor? intake temps?

    I tried just shifting into 5th gear, but I lose too much ET at that point on the track. I should have done more research on the tranny gear ratios. Knowing what I know now, I would have kept the stock 3.31s in it. I probably wouldn't have this problem if I had done that. However, that is where I'm at right now. Any advice would be welcome.
     
  2. PaxtonShelby

    PaxtonShelby FRULE10 Established Member

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    Can you try to set the limiter at 7500?
    What time/mph is the car running?
     
  3. DarkMach1

    DarkMach1 Well-Known Member Established Member

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    Pull fuse 62 and see if it still does it. find a deserted street.
     
  4. Darth Racer

    Darth Racer Member Established Member

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    I did. Still shut off. It ran 11.40 @ 120. Way below potential.
     
  5. Darth Racer

    Darth Racer Member Established Member

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    I did that already. Still shuts down.
     
  6. Red Turtle

    Red Turtle ALWAYS WATCHING Staff Member Super Moderator

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    You could always run a little taller tire and that would get you through the traps currently. What size are you running?

    If the dealer installed the blower, I am assuming that they installed the Roush Tune as well. That being said, how did your local shop tune the car and how did they revert the computer back to factory calibrations in order to tune it. From my understanding, the Roush Tune is not something you can modify, but does seem to be the prevailing cause of your 7200rpm issue.

    In addition, don't most tuners will also lock their file from modifications unless they are provided by them?
     
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  7. Red Turtle

    Red Turtle ALWAYS WATCHING Staff Member Super Moderator

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    In addition, since you have already gone down the tune road that may impede your warranty ability, I would contact some of the top tuners frequently talked about on this site. There is a tone of potential in your set up and waiting to be uncorked.
     
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  8. Darth Racer

    Darth Racer Member Established Member

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    Tires are MT P305/45R17; O.D. 28.1"

    I had problems with the Roush tune. Namely, it would shut down before end of the 1/4 mile. I had a local sheep shop completely remove the tune and start from scratch. New tune on the car, but it still shuts down. Is there a 'secret' electronic bug that shuts power down? I'm out of ideas. Taller tires? I really don't have the excess cash for that right now, but I shouldn't have to! Plus, I could go back to 3.31s, I suppose, but I don't have the money right now. Funds are tight for me, at present. I've never had this problem on any car I've ever owned.
     
  9. biminiLX

    biminiLX never stock Established Member

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    This should be an easy fix with a tune and datalogging.
    Go to a reputable Mustang tuner like Lund, VMP, Palm beach dyno if nobody good local.
    The local sheep shop probably doesn't know horses :)
    Seriously tho if you don't know how to datalog you need to learn or find a different hobby (or break expensive parts).
    -J
     
  10. Darth Racer

    Darth Racer Member Established Member

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    Well, that was helpful. I know about datalogging. At any rate, I think I know how to fix it. Nice try trolling , though.
     
    Last edited: May 28, 2018
  11. Red Turtle

    Red Turtle ALWAYS WATCHING Staff Member Super Moderator

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    The tune is your issue. Contact a well known tuner and they will get you straight.
     
  12. Darth Racer

    Darth Racer Member Established Member

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    Problem solved. Quick parameter change in the tune.
     
  13. ashleyroachclip

    ashleyroachclip Well-Known Member Established Member

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    And which parameter did you change .
     
  14. biminiLX

    biminiLX never stock Established Member

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    Nice trolling, great way to potentially help others.
    -J
     
  15. Darth Racer

    Darth Racer Member Established Member

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    I just changed max allowable RPM to 8000. I had it at 7500. Now crossing FL in 4th gear with no issues.
     

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