Hanging RPM's

Discussion in 'SVT Tech Forum' started by Thunder5.0, Dec 18, 2003.

  1. Have any Cobra owners experience hanging rpm's?
    After warming-up engine , my 99 sometimes hangs at 3000 rpms. It only happens when the engine is warm and I really get on it. The needle just sticks at 3 grand. I know it's not a sticking throttle body or cable. Any ideas?
  2. With the throttle closed, air enters the engine through the idle air control valve on the back of the throttle body. The problem could be the IACV or the systems that control it. Here are some guesses:

    1) Mechanical failure in the IACV. The IACV usually goes out around 50k miles and fails shut (i.e. it sticks closed and your car won't idle at all), but you never know.
    2) Sensor feeding bad information to the computer. I'm not sure how the computer decides how far to open the IACV, so I don't know what sensor it might be.
    3) Computer needs a reboot. The onboard computer dynamically adapts to driving conditions, and I've heard of it getting things wrong, particularly after new mods. You might try unplugging the battery for a while. I've read everything from 5 minutes to overnight, but leaving it unplugged for 30 mins is probably plenty.
  3. Thanks for the suggestions.