Engine Engine Starts, Idles Fine But When I Push The Peddle It Dies.

Discussion in 'SN95 4.6L Mustang Tech' started by Ballista, May 29, 2013.

  1. I replaced the upper intake plenum on my '01 - 4.6L. The install went smooth no real issues. However when I went to test it out I had a real problem; I can start the engine no problem, she idles fine but when I push the peddle she dies. Like it's getting no gas. Restart, great idle, but dies as soon as I open the throttle. I have checked and rechecked all my wires and hoses. Everything is attached, tightened, and connected. Yes, she ran fine before the swap.

    I suspect the TPS went bad? I don't know how to get the codes w/o the code reader so I'm guessing. I metered the TPS but got a dead short across all 3 pins. But of course my meter picked tonight to act up so I don't necessarily trust that reading.

    I don't know how it could have as all i did was swap the old plenum for the new one. The only thing extra I did was blend/flare the throttle body area, behind the throttle plate, to the plenum opening size using conical sanding disks and my die grinder.
    Maybe the vibration broke it?

    Any help is appreciated.


  2. Take a few pics of the install, showing close-ups of the plenum, the MAF, the throttle body ... pretty much anything you touched. You say everything is attached, tightened and connected but that it ran fine before the swap so it would seem that something isn't attached, tightened or connected. Sometimes a different set of eyes looking at your work can help see something you may have missed.
    COramprat likes this.
  3. I agree with trinity...every time I've had an issue after an install there was something I didn't do after putting it together that caused it. Very rarely is there a coincidental problem.

    I'm suspecting the TPS...you removed it to put the plenum on. There is a certain way it goes back on in my experience.
  4. Throttle cable connected at both ends?Try unplugging battery for 15 minutes so computer is forced to learn new idle. Try unplugging TPS and seeing how she starts.
  5. Thank you all for your helpful advice. Oddly enough joshjwc9, your battery suggestion lead to the solution. I had a bad ground connection. I removed the negative terminal wire and noticed the body ground strap was no longer attached. I must have snagged it or leaned on it and broke the last wire strand?!? Anyway, reattached it and all works fine. Would never have suspected something so small could cause such a big deal. Guess I'll just have to make a continuous looop grounding cable like I did for my old ricer.