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Mike V.
Mike V., Auto Service Technician
Category: Car
Satisfied Customers: 25013
Experience:  25 years of experience, Certified Subaru Technician and Nissan factory trained.
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start my car fine but when i take my foot of the gas it stops running

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I can start my car fine but when i take my foot of the gas it stops running
HI there!Does it matter if the engine is hot or cold?Do you have a check engine light on when it is running?
Customer: replied 8 years ago.
no it does not matter, hot or cold, if i try to start it as long as i give it a little gas while i start it, it starts and will run as along as i have my foot on the gas petal it runs fine, but when i let my foot off of the gas it will not idel the way that it is supposed to. it will die immediatly
OK.You may be having a problem with the IAC system.IAC makes idle and air adjustments.Sometimes the IAC motor will get gummed up with carbon and the pintal won't adjust properly.You can remove the iac and clean it with carb cleaner.Make sure to clean the hole it sits in as well.Then put it back on and see if there is improvvement.Here is some info that may help you out:

The Idle Air Control (IAC) valve controls the engine idle speed and dashpot functions. The valve is located on the side of the throttle body. This valve allows air, determined by the Powertrain Control Module (PCM) and controlled by a duty cycle signal, to bypass the throttle plate in order to maintain the proper idle speed.

Click image to see an enlarged viewFig. 1: Typical Idle Air Control (IAC) valve which is mounted to the throttle body-cutaway view shows air bypass direction

See Figure 2

  1. Turn the ignition switch to the OFF position.
  2. Disengage the wiring harness connector from the IAC valve .
  3. Using an ohmmeter, measure the resistance between the terminals of the valve.

Due to the diode in the solenoid, place the ohmmeter positive lead on the VPWR terminal and the negative lead on the ISC terminal.

  1. If the resistance is not 7-13 ohms, replace the IAC valve.
Click image to see an enlarged viewFig. 2: IAC valve wiring harness connections
  1. Disconnect the negative battery cable.
Click image to see an enlarged viewFig. 3: To remove the IAC valve, first disconnect the negative battery cable, then the IAC wire harness plug
Click image to see an enlarged viewFig. 4: Next, remove the two IAC valve attaching bolts ...
Click image to see an enlarged viewFig. 5: ... and pull the valve from the intake manifold
  1. Disengage the wiring harness connector from the IAC valve.
  2. Remove the two retaining screws, then remove the IAC valve and discard the old gasket.
To install:
Click image to see an enlarged viewFig. 6: When installing the valve, always discard the old gasket and install it using a new one
  1. Clean the IAC valve mounting surface on the throttle body of old gasket material.
  2. Using a new gasket, position the IAC valve on the throttle body. Install and tighten the retaining screws to 71-106 inch lbs. (8-12 Nm).
  3. Attach the wiring harness connector to the IAC valve.
  4. Connect the negative battery cable.
Hope this helps!Thanks
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