Question about Chevrolet Corsica

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89 chevy corsica 2.0L TBI has a very high idle any ideas why? I have already ckecked the TPS and it gives .46 volts at the closed or idle postion.

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  • novass2007 Jun 28, 2009

    I do not know. I was reading a haynes manual and it said to check the IAC put a hot wire to each terminial on the IAC and hold it to a good ground and it should run the pintel in and out if it was working correctly

  • novass2007 Jun 28, 2009

    will check for leaks today thank you

  • mike loshbough
    mike loshbough May 11, 2010

    WHAT IS YOUR IDLE AIR CONTROL COUNTS? sorry about the caps

  • javier gallardo Sep 24, 2013

    to me appears DTC:22 and DTC: 44, should i need to buy or replace these sensors???



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Vacuum leak or defective Idle speed control motor

Posted on Jun 28, 2009

  • Clint Smock
    Clint Smock Jun 28, 2009

    If you look in the top of the throttle body you should see a hole that leads into the IAC passage. Plug it with you finger, If the engine dies replace the IAC if it doesn't change the Idle speed, find the vacuum leak.



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See Figures 3, 4 and 5
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  4. Backprobe with the high impotence voltmeter at MAP sensor terminals B and A.
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Fig. Fig. 3: Location of the MAP sensor-TBI system shown


Fig. Fig. 4: Probe the terminals of the MAP sensor to check for proper reference voltage


Fig. Fig. 5: Manifold Absolute Pressure (MAP) sensor wiring diagram

TPS TESTINGSee Figures 2, 3 and 4

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  6. Verify that the TPS voltage increases or decreases smoothly as the throttle is opened or closed. Make sure to open and close the throttle very slowly in order to detect any abnormalities in the TPS voltage reading.
  7. If the sensor voltage is not as specified, replace the sensor.


Fig. Fig. 2: Using a DVOM, backprobe terminals A and B of the TPS sensor to check for proper reference voltage


Fig. Fig. 3: Using the DVOM, backprobe terminals C and B of the TPS sensor, open and close the throttle and make sure the voltage changes smoothly


Fig. Fig. 4: Throttle Position Sensor (TPS) wiring diagram

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