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Thread: Won't idle when cold / auxiliary air valve / idle air control valve

  1. #21
    Van Fan davidgracevan's Avatar
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    Re: ISC Valve

    -no it does not. i think i just worry too much sometimes. keep thingking of effeciency, i was planning to make something that will compensate for the rpm drop when in gear, somekind of added vsv in the engine which activates when gear is not in nuetral or park. oh well, thank you very much sir Tim.

  2. #22
    Administrator timsrv's Avatar
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    Re: ISC Valve

    Keep in mind that higher RPM with vehicle stopped (and in drive) equates to additional energy loss due to drag and more heat/wear to the transmission due to increased slippage. Of course we're talking small amounts, but I think this would be more than enough to offset whatever benefit you may get from "electrical system efficiency". Bottom line is "if it ain't broke, don't fix it". Tim

  3. #23
    Van Fan davidgracevan's Avatar
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    Re: ISC Valve

    - thank you sir Tim for a reminder. i'm just trying to imitate the newer A/T s of toyota, studying how the toyota's ECT works, it could be applied to the van. innovating and trying to improve van's capabilities. i really love it so much. thanks again sir. i'll be posting if the plan was a success.

  4. #24
    Van Enthusiast gushaman's Avatar
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    Re: ISC Valve

    i dont suppose there is an option for an under/overdrive pulley for our alts? i know some performance folks use larger or smaller pulleys to make things spin faster/slower. I do know the van alt has a small pulley

  5. #25
    Administrator timsrv's Avatar
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    Re: ISC Valve

    I suppose if you were using the van for a purpose other than what it was designed for AND problems arose, then perhaps there would be merit for making changes. In my life there are enough problems to deal with that are urgent. Unless I ended up walking home I wouldn't consider this one of them.

    Yes, you could possibly speed up the alternator. Then you have to wonder how fast is too fast? What if by messing around with it you traded an non-problem for a real one??? Just saying

  6. #26
    Van Fan davidgracevan's Avatar
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    Re: ISC Valve

    -thanks guys for the infos and reminders. i'm not just looking at the alternator's effeciency, i'm also looking at the engine's effeciency. studying our van's engine, it runs effeciently at 700-750 rpm, lower than that we can notice that it idles a bit rough, a noticable vibration will be felt, thats why i'm aiming to imitate the Electronic Controlled Transmission of Toyota in the newer vehicles to help the engine run at optimum, and also will help the alternator run at its optimum... theres no bad trade to see... as you have said sir Tim, our van's engine management is a bit primitive, thats why i'm trying to improve it by adding components that you can see at the newer age vehicles...

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    Re: ISC Valve

    This was an interesting thread to read. Although I must say if you are looking to mimic what is going on in todays cars, it might be a better Idea then trying to make old work like new, just find a local junk yard (not u pull it or pick a part). They usually get autos that have been in wrecks and such, find one that hasn't been sitting long and is Newer model and do a swap i mean as long as you get the PCM and TCM you could just have a shop make motor mount adapters and voila you got a sweet modern engine.

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    Won't idle when cold / auxiliary air valve / idle air control valve

    Now that I've installed a new TPS and adjusted the idle speed to 750 rpm when warm, my van runs and idles great except for one thing: when I first start it cold, it'll die if I don't hold the throttle open a bit for a minute or so. After that, all is well. Does this sound like a cold start injector problem? Or maybe a timer controlling the cold start injector? Advise on this would be much appreciated.

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    Administrator timsrv's Avatar
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    Re: Won't idle when cold

    Could be this, could also be a faulty air valve. In the FI section of the factory service manual there are tests for both of these. The cold start injector time switch is tested using an ohm meter. The air valve is tested by removing the hose (when cold) and trying to blow through it. It should allow flow when cold but prevent it when engine comes up to temp. Tim

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    Re: Won't idle when cold

    Thanks very much. I'll have a go at testing both of them. I'll let you know what happens .
    Linn

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    Re: Won't idle when cold

    Quote Originally Posted by linnharding View Post
    Thanks very much. I'll have a go at testing both of them. I'll let you know what happens .
    Linn
    Linn, did you get 'round to testing those components? I'm curious to know if you identified the problem.

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    Re: Won't idle when cold

    Thanks for following up. I'm embarrassed to say I haven't dealt with the problem. Throughout the summer, I only had to hold the throttle down for 10 seconds or so and that was just too easy. My trusty van isn't seeing much action these days since I got a 2000 Honda Insight. It needed a $25 dollar transmission input shaft bearing and I got the car for $1000 so this has become my main ride these days. 65 mpg is average, 75 if I work at it. I'll get back to my van soon and when it's fixed, I'll post it.
    Thanks again for following up.

    Linn

  13. #33
    Van Fan Previa dude's Avatar
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    Re: Won't idle when cold

    I have the same problem. its hard to start when cold. i have to step on the gas for about five seconds. Tim dose that sound like a cold start valve? i tested the ohms and it was 5.6. the books says between 2-4 ohms. could that throw it off by being 1.5 ohms over? i have not tested the timing switch for the cold start vavle yet. what do you think Tim?

  14. #34
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    Re: Won't idle when cold

    I see in your signature you only have a Previa listed........so I gotta ask are we talking a Previa or a van? If Previa, please post your question in the Previa Tech section. If you are asking about a van, then we're good. You should read through the FI section of the manual as it gives detailed answers to your questions. I'm a little confused with your terminology. When you say "cold start valve" are you talking about the CSI (Cold Start Injector) or the Air Valve? The CSI should have a resistance of 3-5 ohms. If I saw a reading of 5.6 I would say it's probably okay (Electrically anyhow........that doesn't mean it's not clogged or leaking).

    Another component that affects cold idle speed is the Air Valve. The air valve is sandwiched between the two halves of the intake manifold. It should be partially open when the van is cold. You won't be able to visually see this when it's installed, but you can find out by pinching one of the tubes that goes to it. When the engine is cold, start it up and pinch a tube (best one attaches to the bottom side of the throttle body intake tube............it's the bigger one that goes towards the rear of the engine). Use a pair of long nose vice grips or something similar to pinch it off. When cold you should see RPM's drop with the hose pinched. If the RPM's are already low it may stall (this is an indication the air valve is good). If RPM's do not change then the valve is bad. After it warms up, pinch it again. This time it shouldn't drop but up to 50 RPM's is allowed. If RPM's drop more than 50, then the valve is bad. The electrical connector for the air valve is accessible from the front of the intake area below the cold start injector. When warm (about 180 deg) the resistance on it's terminals should be 40 - 60 ohms.

    The Cold Start Injector Time Switch is mounted on the driver's side of the coolant filler neck. Here's a copy/paste from the manual to show how it's tested. Tim


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    Re: Won't idle when cold

    Sorry about that Tim. I own only a Previa. It was however for my friends mom. She has an 88 le van with only 65k on it. I didn't think it was any thing major. It was just a clogged fuel filter. I guess it has never been changed all these yeas.lol anyways yeah one of the guys here at my job called the cold start injector a cold start valve. After looking online its an injector, so ill smack my friend at work for calling it a valve and making me look like a fool.lol

  16. #36
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    Re: Won't idle when cold

    My van idles pretty rough in the cold when I start it up. Does any one have the part number of the idle air control valve? Im thinking about buying a new one from toyota and seeing if it makes the van run smoother.

  17. #37
    Administrator timsrv's Avatar
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    Re: Won't idle when cold

    These are expensive and hard to replace so I would test and verify it's bad before replacing. It's Toyota part #22230-73011. MSRP is $281.17 or it can be purchased via a discount internet Toyota parts site for ~$200. www.rockautoparts.com used to have aftermarket ones until recently (probably sold out), but you can still get on eBay: http://www.ebay.com/itm/New-Kyosan-A...a59fd1&vxp=mtr. It's mounted to the underside of the top intake manifold & requires the upper manifold to be removed in order to replace. Tim

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    Air Valve Test

    I don't believe my air valve is working. the van idles the same cold and hot. The 2 pins ohm out as good.


    How much does the air valve raise idle when the van is cold, if its

    Name:  air valve.jpg
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    I want to eliminate it while my intake is off if its not working or not getting signal.
    Anything to reduce the complicated plumbing and eliminate vacuum lines.


    Thanks!

  19. #39
    Administrator llamavan's Avatar
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    Re: Air Valve Test

    When you start the van, does it run rough and want to die (or actually die if not given gas)?

    Gwen
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    Re: Air Valve Test

    No but I have to floor it to make it start in less than 30 sec of cranking.
    (probably a separate issue, Fuel safety switch or 5th injector.) happens regardless of summer or winter.

    I need someone to squeeze their hose while the van is cold and see how much RPMs drop.

    Part of this is evaluating if the air valve is worth having. (faster warmup is all its providing.)

    I could rewire the AC idle up switch for a selectable high idle.

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