Rough idle, stalling after track session

Discussion in 'Drivetrain, Exhaust and Electrical' started by docs302, May 19, 2019.

  1. docs302

    docs302 TMO Race

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    Running an HOD event today at Pocono. First time on the track this year. Only changes I did to the motor this year was add a JLT CIA, Peterson catch can set up and AED tune. First two sessions the car ran strong with no issues. I let it sit two hours for the lunch break. When I started her up for the third session I noticed the it felt like the car had a miss with a very lumpy, erratic idle and then it stalled. It would start right up but immediately go into the rough idle and then stall. I was able to rev it enough to get it on the trailer and back into the garage. But with a 4 straight days of running coming up in three weeks including Watkins Glen, I am under the gun to get this resolved. Any ideas? Bad coil? I quickly checked the 2 vacuum caps I placed over the JLT intake tube but they seemed secure.
     
  2. TMSBOSS

    TMSBOSS TMO Addict

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    Any codes??
     
  3. VoodooBoss

    VoodooBoss Rick Moderator

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    A few random things if nothing obvious comes up.

    Reinstall the stock tune

    Change the oil and look for metal shavings. If so pull the #8 plug and see how it looks.
     
  4. docs302

    docs302 TMO Race

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    No time to check yet. Got home last night and traveling today so it will have to wait. Hopefully I can hook up the scan tool Wed night.

    Yeah that was also on my list.

    I don't want to even imagine that scenario. I have to say I was pretty insensitive to the rev limits yesterday. Hit the limiter many times and saw 8K often. If Joe Aquilante can take the car next week I will drop it off with him. Supposed to be at the Glen in two weeks so I hope this is not my season after one event.
     
  5. captdistraction

    captdistraction I am the breaker of things

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    Easy stuff like checking codes

    then Spark, Fuel, Air.

    Probably worth looking at the plugs, checking the MAF connector and sensor, making sure all harness connections good, ensure fuel is in the tank, check for vacuum leaks (those plugs, the brake vacuum feed, PCV and intake manifold to head interface are common areas), sample the oil (a quick check of the magnetic plug, or just change it since there's the possibility of issue). Start simple, then work towards more invasive.

    No bad mechanical sounds outside the rough idle?
     
  6. wwilde001

    wwilde001 TMO Addict

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    Once you check for codes, check for O2 sensor. I had a similar experience and it's amazing what a singe bad O2 sensor will do.
     
  7. docs302

    docs302 TMO Race

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    No, car was turned off working perfectly and then the next start was just a rough idle that would end up in a stall after a few seconds. The car drove off the track with no issue. Something changed while it was off for two hours.
     

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