TVS Mustang Rough cold start

Discussion in 'Forced Induction - 5.0L V8 Engine' started by Tys5.OH, Feb 20, 2020.

  1. Tys5.OH

    Tys5.OH Member

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    Hi Guys,

    I recently installed a VMP Gen2r on my 17 GT. During cold starts the car will fire up and then stall after a few seconds. If I give it gas for a bit it will run on its own and when its warm it runs and drives perfectly fine. My tuner thinks it may be a vacuum leak but I sprayed carb cleaner everywhere and don't get any change in idle. Anyone have a similar problem or know what it may be?

    Thanks
     
  2. robwlf

    robwlf Well-Known Member

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    sounds like a vac issue get a smoke test done, im tvs also and have no issue with cold starts.. carb cleaner will only do so much...but a smoke test will pin point where the leak is .. if there is a leak.. could also be a throttle body prob. i dont know if theres a relearn process like dodge has. dodge ( turn key to on but not start,slowly push pedal to floor then gradually come up )
     
  3. Cory S

    Cory S Well-Known Member

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    Tuner needs to add a little fuel enrichment for cold starts.
     
  4. OP
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    Tys5.OH

    Tys5.OH Member

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    Yea, I'm going to take it to get smoke tested just so I can confirm there aren't any vacuum leaks.
     
  5. OP
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    Tys5.OH

    Tys5.OH Member

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    My car does run pretty rich at cold start. But my tuner said he could try to remove cranking fuel but doesn't recommend that as a solution. Tuned by Lund.
     
  6. Bahndvr

    Bahndvr Roushcharged

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    After cold start runs for ~2 seconds RPM drops ~500 then recovers.
     
  7. Roh92cp

    Roh92cp Well-Known Member

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    I had the exact same issue when warm startup is perfect. Cold starts would stall after several oscillations, and the colder the worse the startup was. Tuner first tried adding more fuel which didn’t work so we went leaner and after doing leaner a little at a time it got better. After 8 leaner and leaner calibrations the cold startup worked and now starts cold without stalling.
     
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  8. Cory S

    Cory S Well-Known Member

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    We ended up doing this as well.
     
  9. Roh92cp

    Roh92cp Well-Known Member

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    I thought you said you added fuel to fix the cold start issue, mine was opposite I leaned it out to fix cold starts.
     
  10. Cory S

    Cory S Well-Known Member

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    After that didn’t seem to help, we went leaner LOL.....
     
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  11. Bahndvr

    Bahndvr Roushcharged

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    Tuner wants me to datalog this but I didn't think that was possible
     
  12. Roh92cp

    Roh92cp Well-Known Member

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    You can data log startup, but you won't get fueling as 02 sensors need time to warm and come on.
     
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  13. Martin5.0sc

    Martin5.0sc Well-Known Member

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    Who’s tuning you guys I’m having the same issue with my tune and every time the tuner tries to fix it, my knock sensor become over active, says he can’t figure out why so screw it rather have clean wot hits and deal with shitty startup, kind messed up thou
     
  14. West TX GT

    West TX GT Well-Known Member

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    I have the same issue. Dakota at Lund told me it is a thing that always occurs with these cars. It's called cold start emissions reduction. He says the car uses negative ignition timing to heat up the O2s as fast as possible. He also said it is more noticeable on some set ups than others. My Edelbrock tune was more noticeable but it still does it. He had me log it and said it was normal. I am just going to give it a quick rev or quickly put it in drive or reverse when it is cold outside.
     
  15. Cory S

    Cory S Well-Known Member

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    You can’t really see start up fueling (lambda) with a log. O2’s are inactive for around 60 seconds during cold start. It’s more trial and error.
     
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