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  1. C

    1992 TBI 454 4L80E. Idle hunts in Park/Neutral but is smooth in drive.

    I replaced it last night when I checked all the throttle passages for IAC and vacuum. Everything was clean. There was no improvement to the idle in park/neutral.
  2. C

    1992 TBI 454 4L80E. Idle hunts in Park/Neutral but is smooth in drive.

    I agree it appears I have high vacuum when in park/neutral. What causes high vacuum? The MAP sensor chart appears to be correct. The O2 voltage swings between 200mv and 900mv when the idle surge is happening in park/neutral. I agree it appears I have high vacuum when in park/neutral. What...
  3. C

    1992 TBI 454 4L80E. Idle hunts in Park/Neutral but is smooth in drive.

    '94 and up TBI big blocks required the higher fuel pressure
  4. C

    1992 TBI 454 4L80E. Idle hunts in Park/Neutral but is smooth in drive.

    I have not touched the idle screw and it is not suppose to have the vacuum throttle kicker. I have done a lot of data logging and it looks like my MAP voltage in park/neutral is low (~.88/.90 volts) it is suppose to be 1-2V at idle. When I am in gear the MAP sensor voltage is within spec...
  5. C

    1992 TBI 454 4L80E. Idle hunts in Park/Neutral but is smooth in drive.

    It does not have the vacuum-operated throttle kicker. I have not unsealed the minimum idle speed screw.
  6. C

    1992 TBI 454 4L80E. Idle hunts in Park/Neutral but is smooth in drive.

    Hi, Thanks for the suggestions! The EGR is functional. The fuel filter was replaced with the fuel lines. I do have the service manuals too. I did not clean the passage for IAC I will check that. UPDATE: My fuel pressure was too high at 26PSI for a 1992 TBI. I replaced the regulator and am at...
  7. C

    1992 TBI 454 4L80E. Idle hunts in Park/Neutral but is smooth in drive.

    Hi Everyone, I have been chasing down a idle hunting problem recently. My issue is that in park/neutral the engine idle will hunt for the a stable engine speed. This happens after the engine warms up. When I shift into drive the engine speed stabilizes. The AFR in drive is rich around 11. The...

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