cobradad Posted December 2, 2014 Report Share Posted December 2, 2014 My '07 Shelby GT (manual Transmission) with 54K just developed a problem. At idle with the clutch all the way down the idle is fluctuating about 50-100 RPM from "normal" After about 5 seconds the idle goes up for about a second, drops and then repeats after another 5 seconds. Has anyone run into anything like this? Any ideas what might be going on? The car was running fine last Wednesday. Clarence Link to comment Share on other sites More sharing options...
shel-b001 Posted December 3, 2014 Report Share Posted December 3, 2014 My '07 Shelby GT (manual Transmission) with 54K just developed a problem. At idle with the clutch all the way down the idle is fluctuating about 50-100 RPM from "normal" After about 5 seconds the idle goes up for about a second, drops and then repeats after another 5 seconds. Has anyone run into anything like this? Any ideas what might be going on? The car was running fine last Wednesday. Clarence Could it be the MAP sensor , try disconnecting the battery for a minute , sometimes that helps unscramble the computers brain & reset everything.just a thought Link to comment Share on other sites More sharing options...
2010KonaBlueGT Posted December 3, 2014 Report Share Posted December 3, 2014 Is it naturally aspirated or forced induction? Either way, it's sounding like false (unmetered) air is getting past the MAF sensor. Don't forget to start with the basics, making sure everything else (besides computer control inputs/outputs) is good. Igniton system, vacuum leaks, etc. Throw a vacuum gauge on the intake manifold port to see what it is telling you. That's a real good place to start. Phill Link to comment Share on other sites More sharing options...
cobradad Posted December 3, 2014 Author Report Share Posted December 3, 2014 Phill, Shelby001, Thanks for the leads/thoughts. I will take a look this w-end and see what is going on. The car is naturally aspirated so I was thinking either a fuel or air issue. The car has been trouble free up to now. Link to comment Share on other sites More sharing options...
old man Posted December 4, 2014 Report Share Posted December 4, 2014 Try cleaning the throttle body. Brenspeed has a video of how to do it. They state this is the most common problem with poor idle. Simple to do and probably would be good to do with your mileage. Good luck. Harley Link to comment Share on other sites More sharing options...
ledfoot73 Posted December 5, 2014 Report Share Posted December 5, 2014 I second cleaning the throttle body. It will cause rpm fluctuations at idle when dirty and if it hasn't been done yet you're long overdue. Cheapest and easiest place to start. Link to comment Share on other sites More sharing options...
2010KonaBlueGT Posted December 5, 2014 Report Share Posted December 5, 2014 I second cleaning the throttle body. It will cause rpm fluctuations at idle when dirty and if it hasn't been done yet you're long overdue. Cheapest and easiest place to start. I agree, I third it. I've fixed *many* EFI cars by cleaning the throttle body/blades. When the coke up it messes with the minimum idle setting (air bleed) and causes all kinds of havoc. But in all honesty, it's always been stalling when coming to a stop that I've cured by cleaning a TB, not idle surging. But X 2, like has been said, way overdue and it's something that needs to be done periodically anyway. Phill Link to comment Share on other sites More sharing options...
cobradad Posted December 6, 2014 Author Report Share Posted December 6, 2014 Ok. Found the video. What about needed gaskets putting things back together? Clarence Link to comment Share on other sites More sharing options...
2010KonaBlueGT Posted December 6, 2014 Report Share Posted December 6, 2014 Ok. Found the video. What about needed gaskets putting things back together? Clarence You don't need to remove the throttle body to clean it. It even say so at 1:30 of the video. Spray some carb cleaner on a shop rag and be sure to get the *edges* of each throttle blade as well as the throat where the blades rest. If you can avoid spraying a bunch of cleaner (puddle) into the TB, try not to. But it's okay if you do. Phill Link to comment Share on other sites More sharing options...
cobradad Posted December 28, 2014 Author Report Share Posted December 28, 2014 Greetings all, Sorry for the delay. We had a close friend pass away earlier this month. I cleaned the throttle body as everyone suggested and it seems to have solved the problem. The idle is nice and steady as it should be. And yes after 7 years and 54K miles the inside of the throttle body was quite dirty. Thanks everyone for the assist on this. Clarence Link to comment Share on other sites More sharing options...
vapor08GT500 Posted December 28, 2014 Report Share Posted December 28, 2014 Glad you fixed it. I can't stress enough on cleaning the throttle bodies on the 3V's. 2 most common things I see when Ford dealers send cars to my shop are 3V throttle body issues, and GT500 supercharger pulley installs gone wrong.... Alex Link to comment Share on other sites More sharing options...
old man Posted December 28, 2014 Report Share Posted December 28, 2014 Sorry to hear of your friends passing. I am happy this simple thing fixed you car. Best wishes for the new year. Clean those TB's everyone. Harley Link to comment Share on other sites More sharing options...
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