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Bouncing Idle when cold - Not MAP/PCV/Cleaned IACV/FITV

Discussion in 'General Tech and Maintenance' started by wanderinman, Apr 20, 2006.

  1. wanderinman

    wanderinman Senior Member

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    When the car first starts up the idle will bounce from 1500 to 2500 with a pretty regular beat. The guy I bought it from said it was a bad MAP sensor. Just want to make sure that was a legit reason for this problem before I spend the money on a new one.
     
  2. VTECin5th

    VTECin5th Administrator

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    Possible/more likely the IACV... no check engine lights?
     
  3. Turbo&Auto

    Turbo&Auto Nick Go FAST!!

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    Could be the MAP, also could be the front O2 sensor.

    When I started my car after the end of the project it did the same, I had the O2 wiring a lil off. After I fixed that the problem went away. Maybe your O2 is bad, how old is it?
     
  4. wanderinman

    wanderinman Senior Member

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    The car has 232K on it. Its a stock motor/tranny no swaps. Only mods under the hood are a short ram intake. And no, the check engine light wasn't on.
     
  5. Turbo&Auto

    Turbo&Auto Nick Go FAST!!

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    Its possible its the O2. How about checking all your vacuum lines too.
     
  6. MikeBergy

    MikeBergy Blah blah blah....

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    I doubt it is the O2, especially since the ecu doesn't look for the O2 sensor until it switches to closed loop mode. I'd say either the EACV/IACV or the fast idle thermo valve (FITV) both of wich are located next to the throttle body. Clean those bad boys out with some wd40 and some compressed air, and then check and see if you still have your idle problems. It could be a MAP sensor, but if you are only getting these problems when the engine is cold, it's probably not the MAP sensor.
     
  7. Turbo&Auto

    Turbo&Auto Nick Go FAST!!

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    When I had no front O2, the car would do this even before it warmed up. Thats why I thought the O2 could be an issue, it does have 220K on it too.
     
  8. MikeBergy

    MikeBergy Blah blah blah....

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    for what car? I see in your sig you have a 92 accord, which would be obd1, and a bit different than his 91 accord, which would be obd0. I don't know, I guess anything is possible. I had my o2 sensor completely disconnected, and nothing happened until after the car warmed up and went into closed loop.
     
  9. VTECin5th

    VTECin5th Administrator

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    Some 91s are obd1, we just got one from 2/91 that is obd1 :)
    I would just pull the IACV and clean it up, and clean the IATS too.
     
  10. MikeBergy

    MikeBergy Blah blah blah....

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    Well, shoot. I guess I got robbed of a better EMS... I thought Honda as a company made the switch to obd1 in 1992. Learn something new everyday.
     
  11. wanderinman

    wanderinman Senior Member

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    Ok, lots of input. I'll be cleaning those things tomorrow and let y'all know if it worked.
     
  12. Turbo&Auto

    Turbo&Auto Nick Go FAST!!

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    Thats my bad as well, I assumed since the 90-93 are the same looking that the electronics would be the same. I learned something new too :)
     
  13. wanderinman

    wanderinman Senior Member

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    Ok, here's the newest info I got....

    No check engine lights when the car is usually running, in fact I've never seen one except as described below.

    Cleaned the IACV and the FITV both out. Engine still had a bouncing idle. It also does it when its already warmed up, not just cold. When I completely unhooked the IACV with the engine running the idle still bounced, just much less pronounced. 1000-1200 rapidly w/ a check engine light (duh) instead of 1500-2500 slower. Also the FITV is working as advertised, pulls air when the engine is cold, and stops when its warm. I guess I will give the o2 a shot, it probably needs to be done anyway.

    Quickly though, I did find a bit of engine oil in the IACV, nothing major, a few drops mostly, but any ideas on that? I guess it came in through the PCV valve and ran down the inside of the intake manifold.

    I'll post later after I replace the o2, hopefully its cheap like my Troopers was (the troopers was $6.95).
     
  14. wanderinman

    wanderinman Senior Member

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    Holy crap parts were expensive...

    80ish for an o2, 178.99 for the IACV, and 98.99 for the FITV.

    Anybody got spare parts laying around they wanna sell me?
     
  15. Turbo&Auto

    Turbo&Auto Nick Go FAST!!

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    What about the PCV valve? I know it usually makes the car smoke if its bad, but it is a vacuum controlled lil device. It could be stuck partially open and cause that fluctuation. They're only like $3 too.
     
  16. wanderinman

    wanderinman Senior Member

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    I'll check that, it would account for the oil in the intake manifold. However, the engine is still burning clean as a whistle, 233K miles and nothing out the exhaust pipe.
     
  17. wanderinman

    wanderinman Senior Member

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    I'm scared to, but I will. I'll post results tomorrow.
     
  18. wanderinman

    wanderinman Senior Member

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    Not the PCV, I replaced it to no avail.
     
  19. Turbo&Auto

    Turbo&Auto Nick Go FAST!!

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    ^At least it was cheap. Def a stumper you got there.
     
  20. wanderinman

    wanderinman Senior Member

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    Yea, its killing me. I am going to replace the MAP sensor as soon as I get around to finding one thats not an arm and a leg. They have them like crazy on EBay. Hopefully getting one for 9.99 instead of $248 or whatever Autozone wanted.
     
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