Erratic idle and hesitation under load.

Discussion in 'Generation 4 - Maintenance & Troubleshooting' started by Andrew C, Sep 4, 2019.

  1. Andrew C

    Andrew C New Member Supporting Member

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    2015 non pp.
    I just finished a 5000 km trek across the country and during the trip she started with the whole hesitation thing under light load, I've since sucked out the intercooler and cleaned the airflow sensors. But the car is still doing it. It seems to come and go at random... fuel pump? Computer issues? as I am at a very different altitude than home? I also have recently put in new iridium Ngk's and gapped them to 32. Any help would be great thanks.
     
  2. Lostneye

    Lostneye SHO Member

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    First tighten the gap to 30.
     
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  3. Andrew C

    Andrew C New Member Supporting Member

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    The old original ones were at 40 when I took them out so I'm pretty sure they're not the issue. What difference would the 2 thou make?
     
  4. Aaron Marty

    Aaron Marty Trying....

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    I've been dealing with this issue ever since I've had my car. It's been three years now......still can't figure it out. It's extremely annoying. I've done everything under the sun to try and solve it. Good luck man.
     
  5. SHOdded

    SHOdded SHO Member Supporting Member

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    In forced induction applications, small changes in plug gap are magnified in effect. It is well worth following Lostneye's recommendation and getting all new SP534 plugs, of if you are a bit adventurous, SP542s that I believe are gapped 0.028 from the factory and are 1 range colder. If tuned, the SP542s might be the fix.
     
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  6. Lostneye

    Lostneye SHO Member

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    I have never checked the gap when removed but when running 534s gapped at 30 I could tell if they needed to be changed by how the car idled. Since switching to 542s at 26 the car idles much better.
     
  7. Andrew C

    Andrew C New Member Supporting Member

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    Well I took your advice and Installed new OEM sp534 plugs. They actually have a new part number (sp 580) and I'm sad to say there is absolutely no change whatsoever. I notice on a downshift sometimes she'll gear down, and rev right up, but not accelerate a whole lot. It's got me thinking turbo maybe ? But what do I know.. if it's not a 2 stroke or an oldschool pushrod I'm kinda lost. Lol
     
  8. SHOdded

    SHOdded SHO Member Supporting Member

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    Is it a hesitation or a shudder? Shudder under light load can be the PTU.
     
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  9. Aaron Marty

    Aaron Marty Trying....

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    Mine has been shuddering for years now an it got a new ptu put in less then a year ago
     
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  10. Andrew C

    Andrew C New Member Supporting Member

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    It's definitely a hesitation. Like a misfire, but it's so intermittent I'm starting to lean toward a vaccum leak somewhere in the boost department.
     
  11. Aaron Marty

    Aaron Marty Trying....

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    I boosted leaked my car with smoke test. It was fine. Still hesitation.
     

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