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Thread: IACV issues

  1. #1
    DX User ADSA20's Avatar
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    IACV issues

    Hey guys, so after chasing a coolant leak after some overheating issues I discovered my IACV was cracked. These are VERY rare around here and luckily I had a spare I cleaned up and put in. It does however now idle quicker ( that's not all bad it stops the vibration in the old auto lol ) hence a couple of questions..

    What should my cold idle speed be on start up? As on a dead cold start it will sit at 2000 for about 30 seconds then slowly drop to around 950 and sit there once warm.

    Since changing the IACV I seem to be getting what I can best describe as surging but the strange part is it only does it at low speed. Like when I coast up to a stop light or let my foot off the gas.

    Can I adjust with the black screw thing that forces the spring down inside the valve? I know there is an idle adjustment screw elsewhere but I was told by a mechanic friend to NEVER touch it.

    Thanks

    Accord Si 87 auto fuel injected.



  2. #2


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    Re: IACV issues

    Quote Originally Posted by ADSA20 View Post
    Hey guys, so after chasing a coolant leak after some overheating issues I discovered my IACV was cracked. These are VERY rare around here and luckily I had a spare I cleaned up and put in. It does however now idle quicker ( that's not all bad it stops the vibration in the old auto lol ) hence a couple of questions..

    What should my cold idle speed be on start up? As on a dead cold start it will sit at 2000 for about 30 seconds then slowly drop to around 950 and sit there once warm.

    Since changing the IACV I seem to be getting what I can best describe as surging but the strange part is it only does it at low speed. Like when I coast up to a stop light or let my foot off the gas.

    Can I adjust with the black screw thing that forces the spring down inside the valve? I know there is an idle adjustment screw elsewhere but I was told by a mechanic friend to NEVER touch it.

    Thanks

    Accord Si 87 auto fuel injected.
    I would first bleed the coolant and then bleed the eacv. The port driver side is the coolant out on my car an 88.

    Fast idle i adjust the fast idle plunger on the throttle body. You remove the cover and screw the plunger with a quarter. I put mine at 1500 rpm but i live in a warm climate. I was worried more about dry starts at that rpm.
    1988 Lxi owner since August 1995
    336k miles running strong!
    Now running E85.

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  3. #3
    DX User ADSA20's Avatar
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    Re: IACV issues

    Quote Originally Posted by Oldblueaccord View Post
    I would first bleed the coolant and then bleed the eacv. The port driver side is the coolant out on my car an 88.

    Fast idle i adjust the fast idle plunger on the throttle body. You remove the cover and screw the plunger with a quarter. I put mine at 1500 rpm but i live in a warm climate. I was worried more about dry starts at that rpm.
    Yeah, this has only happened since I changed the IACV, it's been purring like a kitten before that. I noticed today on the way home from work that the rpms are too high while driving too. 100kmph on the freely and it pushed 3000rpm, I backed off it a little and it dropped to 2900-2800rpm.. Not normal at all? Feels like it's revving hard too. Watched it in town close and it's at 2000rpm at 60kmph. Could the IACV affect this? Has to be, never seemed to rev so hard before I switched it. And yes, I adjusted the plunger down with no change, I'm going to take it off and have a better look at it tomorrow afternoon.

  4. #4
    LX User niles's Avatar
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    Also when you're under the hood take out the idle adjustment screw and check the o-ring. It could be leaking air. That's what mine did, the o-ring was rock hard and air was leaking through causing high idle

  5. #5
    DX User ADSA20's Avatar
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    Re: IACV issues

    Quote Originally Posted by niles View Post
    Also when you're under the hood take out the idle adjustment screw and check the o-ring. It could be leaking air. That's what mine did, the o-ring was rock hard and air was leaking through causing high idle
    Sprayed around it and found yes, there's an air leak in the new IACV I put in. So I'll replace the o rings and reseal it and check where you suggested as well. Still I'm wondering if this could cause higher rpms during actual driving as well. Seems to me that 2800-3000 rpm at 100kmph is a bit much.

  6. #6

    Dr_Snooz's Avatar
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    Re: IACV issues

    Quote Originally Posted by ADSA20 View Post
    Still I'm wondering if this could cause higher rpms during actual driving as well.
    Clutch or trans are slipping?
    Dr_Snooz

    "I like to take hammers, and just break stuff, just break stuff." - Beavis


    1989 Honda Accord LX-i Coupe, 240k miles, MT swap, rear disc swap

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  7. #7
    DX User ADSA20's Avatar
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    Re: IACV issues

    Quote Originally Posted by Dr_Snooz View Post
    Clutch or trans are slipping?
    This entered my mind. It's 2000kms away from been due for a transmission service and I've noticed a slight humming when reversing. I planned on having it checked out, just seemed strange that this started after I replaced the IACV.

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