1994 honda civic Idle problem?

Hey i have a 1994 honda civic with a 1999 jdm motor swap. i cant figure out my problem. when i shift the car into nutral it has a idle that jumps up and down from 1000 to around 1700 rpms, its annoying and sounds like im rev"ing the engine. heres the catch, i have already takin out the IACV and it wasnt even clogged buti still sprayed carb cleaner on it, let it dry and reinstalled it. i also already bought a new pcv valve today too, and put dry gas in the gas to clean fule lines, nothing has seemed to work and i need help!! thanks

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  • SoCal
    Lv 6
    1 decade ago
    Favorite Answer

    Vacuum leak or the IACV is faulty. If the IACV is faulty no matter how much you clean that thing the car is gonna idle like crap. Go over the wiring and everything on the intake manifold and make sure nothing is loose, broken, and everything connected/wired correctly.

  • 1 decade ago

    Sounds like you may have an IAC problem. Does it do it when its cold as well as warmed up? Only in neutral or in gear as well? Automatic or Manual Trans.? Try taking the IAC valve off and use a piece of duct tape to tape the round port shut thereby blocking it off then bolt it back on. If the idle surge goes away then you know it's IAC related. But don't leave the duct tape there! Cause it will eventually get sucked in the motor..good luck and hope this helps..

    Source(s): Certified Honda Tech
  • 1 decade ago

    I had a similar issue in one of my tegs. I thought it was the IACV but it wasn't as I used another and probblem stayed. I searched and search for a vacume leak and couldn't find it. It ended up being my FITV (fast idle thermo valve.) Since you have a 99 swap you might not have one because they stopped coming on OBD2 hondas in 96. But if you do for some reason it is located on the bottom of the trhottle body and has one coolant line attached. Take it off by removing 3 bolts and look inside they will be a screw. My screw was very loose causing the issue, but take out screw and clean inside while its off, tighen snug screw and reinstall. Hopefully you have one as it will be a easy fix.

    GL

    Source(s): Own 3 tegs and 2 civics
  • Anonymous
    1 decade ago

    sounds like it might be a vaccume leak somewhere and the ecu is trying to compensate for it.....if it was your iac it would rev an stay

    Source(s): built, stroked and boosted h2b 95 hatch runnin 26lbs boosted d16z6 93 hatch daily driver 10lbs untuned
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