New SCT X3 91 and 93 octane tune

Discussion in '2007 - 2014 Shelby GT500 Tech' started by meterman, Aug 17, 2009.

  1. I am new to programming the computer on cars, although I've worked on computers for 10 years. I just bought a 2007 Shelby GT500 Cobra, which is stock. Since the car is set up for 91 octane and it's not available at many gas stations I bought a SCT X3 from a dealer and he made a custom tune for me for both 91 octane and 93 octane.

    Today I picked up the X3 and installed the 91 octane tune and immediately noticed that the car idles around 1500 rpm when I stop and doesn't slow down to 850 rpm for about 6-10 seconds.

    While driving if I let my foot off the gas it feels like I have the cruise control on because the idle is still at 1500 rpm.

    When downshifting I don't get the same engine braking effect either.

    Is this NORMAL and how it should be?

    thanks so much in advance,

  2. doesnt sounds normal to me, especially since it didnt do it before... I would consider contacting one of the more reputable tuners on the net and if theyre close to you getting a custom dyno eval...
  3. Thanks, acutally after letting the car sit for a few hours everything seems fine. Not sure if it's because I didn't shut the car off after installing the tune. Now the car runs GREAT. the boost kicks in as soon as I punch it, where it had a few second lag.