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  1. #1
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    cold start 97

    My 97 has had cold start problems ever since I bought it last summer. I thought they would be easy to fix. HAHA!

    Toyota just replaced the engine with a JDM and it still has the problem. It will start, but you need to give it gas to keep it running. If you don't, it dies. Once it runs for 30-60 seconds its fine, and when warm it starts up again fine.

    They tried a different, used throttle body, which solved that problem but caused a dangerously high idle. That being an even worse problem, I told them to put the old one back in. They cleaned it all up, again, but the problem remains.

    This seems like it would be a cold start injector problem, but my 97 DX did not come with a cold start injector and is not wired for one. I'm stumped. They are stumped. I have an experienced tech working on it and he's stumped, unless we just need to get the right throttle body in there.

  2. #2
    Van Fan
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    Re: cold start 97

    Here's what I think it might suggest - that you have two bad throttle bodies - there's an Idle Speed Control module attached to the throttle, controlled by the coolant temperature. Since the symptoms change with the throttle body - assuming the same ISC wasn't transplanted from one to the other - you've got two malfunctioning ISCs - one stuck closed on one throttle body and the other stuck open on the other.
    "If you find yourself holding a sledgehammer or a crowbar, it's time for a break."

  3. #3
    Van Fan
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    Re: cold start 97

    I was curious so saw what appears to be a lot of relevant posts, one even about a '97 with high idle.

    Google
    toyotavantech.com: previa idle speed control valve
    "If you find yourself holding a sledgehammer or a crowbar, it's time for a break."

  4. #4
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    Re: cold start 97

    The tech who installed my JDM engine seems to have considered these other options and he seems to believe it is the throttle body itself that is the problem. I'm not sure what can go wrong in a throttle body itself.

    Now it has warmed up outside and it starts much better but last night it was idling high when I got home. I'll have to see if that impression continues. I will check it for the infamous black flakes but once again the tech assured me that he checked the coolant flow thoroughly.

  5. #5
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    Re: cold start 97

    Well, the Idle control valve is normally part of the throttle body - or I guess you could call it an assembly - so maybe there are some semantics at play, since I agree with you the body itself is a piece of metal with openings in it that are either clear or obstructed (and I count the throttle plate getting stuck sometimes on deposits as an obstruction). Not sure what you meant by coolant - it does circulate there to keep things toasty, but the valve is controlled by the ECU which reads engine speed and coolant temperature from sensors mounted elsewhere. If the motor or solenoid or whatever it is in the ICS isn't working or the moveable vane in the ICS connected to that is stuck or has limited motion, that sounds like your issue, assuming you've been swapping throttles each with their own ICS attached. The one that can't open internally to send extra air to the throttle acts like a stuck choke - starts well but will over-rev at idle. The other stuck open leans out the a/f mix too much at a cold start, and would matter less the warmer it was.
    "If you find yourself holding a sledgehammer or a crowbar, it's time for a break."

  6. #6
    Van Fan
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    Re: cold start 97

    Sorry, ISC not ICS. Darn TLAs.
    "If you find yourself holding a sledgehammer or a crowbar, it's time for a break."

  7. #7
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    Re: cold start 97

    Not semantics at play if you mean my conversation with the tech. I grilled him to make sure he believed it was the throttle body itself and not the assembly. He responded with something about the tests he ran that went over my head, but was very firm that it was the body of the throttle body, so to speak. He's one of their most experienced techs and used to own a Previa until he sold it (to me, my first) about 23 years ago. Still, something is going on and people can be wrong but I tend to trust his ability to fix it over mine.

    My reference to the coolant was in regard to his response when I asked him about possible black flakes in the intake coolant pipes. He responded by saying he tested the coolant flow to the intake. I just went and cleaned the "T" where flakes collect and got a fair bit out, but I'm not sure that will change anything since clogging there is supposed to cause high idle when cold.

    The last couple of warm days it started perfect.
    Last edited by Previologist; 05-02-2021 at 06:48 PM.

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