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Thread: '97 Previa RWD VERY HIGH IDLE Warm Engine

  1. #21
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    Re: '97 Previa RWD VERY HIGH IDLE Warm Engine

    hi, I'm not sure if this might help. But I remember seeing an article a while ago, possibly on the yahoo group of the supercharged previa's getting black flakes in the coolant and blocking up one of the pipes where it t's off. I'll try finding the article, but here's a pic showing the pipe I believe it is. I used to have a 95 le s/c and the dealership could never figure out it's high idle in the cold.
    scunderhood.jpg

  2. #22
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    Re: '97 Previa RWD VERY HIGH IDLE Warm Engine

    It was toyotanation actually. I asked the question a while ago. cleaning_out_tee.jpg

    http://www.toyotanation.com/forum/85...le-previa.html

    I hope it helps.

  3. #23
    Van Enthusiast tbkilb01's Avatar
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    Re: '97 Previa RWD VERY HIGH IDLE Warm Engine

    yea, i found the source of some black flakes in my coolant by the way ... while I replaced the big water hoses, I noticed that the black paint around the pipes ( guess TOY wanted them to look good?) that connect the hoses is just "Flaking" off. I rubbed all paint off pipe ends and connected hoses... Flushed the system real good afterword..thanks for info...." its what we do"
    Last edited by tbkilb01; 05-05-2016 at 05:15 PM.

  4. #24
    Van Enthusiast tbkilb01's Avatar
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    Re: '97 Previa RWD VERY HIGH IDLE Warm Engine

    OKAY! I had thought the fast idle had gone away miraculously but I was mistaken! So I replaceded fuel filter, replaced fuel pressure regulator, and even swapped out fuel rail with injectors (mine tested 17.2 each and FSM wants them around 14.2). So all in all I ended working EFI system over real good. Ended up replacing cold start injector, cold start time valve, coolant temp sensor, Egr modulator, hoses, PCV, TPS, and list goes on...(found 2 previa at U pull it and worked them over real good too, Yea used parts I know but they worked just the same...didnt remedy or worsen the symptom!) Anywho, after scratching my head over it I decided to check ISC again. I might have to replace ISC? and I was hoping the Previa were still at the bone yard. After removing throttle body for 3rd time, I ran across a sticking valve!! I dont know how I missed it the first time
    but I caught the buggar this time... cleaned it really good till valve moved freely!! Reinstalled on 92 PREV and she definitely purrs.
    So now its up the coast I go! Heading up Atlantic coast!
    Its definitely BEER-THIRTY HERE!
    thank you everybody that chimed in.
    Attached Images Attached Images

  5. #25
    Van Addict cvtroger's Avatar
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    Re: '97 Previa RWD VERY HIGH IDLE Warm Engine

    Yeah, I think these 2 issues are MUST DO if you have a previa.

    The black flakes and EGR clean out. I was so angry that the shop that did my motor ignored the manifold. It could have easily been cleaned out and taken cared of.
    Last edited by cvtroger; 04-30-2015 at 12:33 PM.

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    Re: '97 Previa RWD VERY HIGH IDLE Warm Engine

    Glad to see it helped.

  7. #27
    Van Addict cvtroger's Avatar
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    Re: '97 Previa RWD VERY HIGH IDLE Warm Engine

    I feel this is a must do for the Previa.

    Clean out the IAC valve and put in the "flake filter".


    IAC valve and "flake filter"
    - Fram G15 inline filter - this for the flakes going into the ventilation tube.
    - 2 small hose clamps for the filter.
    - Throttle body gasket - 22271-76020
    - IAC valve rubber gasket - 22215-76010 - gasket between the IACV and Throttle body
    - IAC valve screws (set of 4) - 21821-25180 - holds the IACV to the throttle body

  8. #28
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    Re: '97 Previa RWD VERY HIGH IDLE Warm Engine

    I believe the lowest one is the "Start Injector Time Switch"



    Quote Originally Posted by tbkilb01 View Post
    thanks pdgizwiz,
    had time tonight and checked into coolant temp sensor. I found 3 sensors on water outlet. removed top one and tested it hot and cold, passed resistance as per FSM... middle one just goes to temp guage. The lower one escapes me, couldnt find wrench to fit (bigger than 19mm)....and i could not find the sensor mentioned in FSM. so I started prev and disconnected upper one. It triggered code. Havent had any codes (so I was relieved to see one). I reset CU to see if it comes up again.. at least I know the upper Sensor works...

    lower one does nothing that i can tell...so far. any way to test the lower one you know of? its a water temp sensor for sure just not sure what it sends temp to...i may remove it to get toyota numbers off it and look on rockauto or Toyotaparts.com.
    I'll let car heat up thoroughly tomorrow and disconnect it to see if any effect on prev.
    again thanks for chiming in.
    Did you have a HIGH IDLE problem...?

  9. #29
    Van Enthusiast tbkilb01's Avatar
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    Re: '97 Previa RWD VERY HIGH IDLE Warm Engine

    Quote Originally Posted by Jwsmsmith View Post
    I believe the lowest one is the "Start Injector Time Switch"
    I believe your right, thanks...
    However, my speedometer just stopped working and I'm thinking/hoping speed sensor?
    found picture:
    IMG_4324.jpg
    Last edited by tbkilb01; 02-20-2017 at 11:03 AM.

  10. #30
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    Re: '97 Previa RWD VERY HIGH IDLE Warm Engine

    hopefully it was the sensor that has gone bad
    otherwise, the capacitors in the speedometer itself has gone bad.... that's relatively easy to fix for less than $10 (search for my thread)

  11. #31
    Van Enthusiast tbkilb01's Avatar
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    Re: '97 Previa RWD VERY HIGH IDLE Warm Engine

    Quote Originally Posted by TheMAN View Post
    hopefully it was the sensor that has gone bad
    I've replaced speedometer cluster, VSS and wiring to VSS. Speed still does not register. Computer problems?

  12. #32
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    Re: '97 Previa RWD VERY HIGH IDLE Warm Engine

    Regarding the original problem posted in this thread I had exactly the same issue in my 97 AWD Previa: slightly high idle on cold start, increasingly fast idle as it warms up. Surging idle in Neutral, very fast idle in drive or park (or stopped in neutral). Undriveable.

    I first tried the coolant temp sensor. Didn't change anything.

    I next assumed it was the Idle Air Control, so I ordered a new one (off eBay! Huge mistake). I changed it, but got no improvement.

    Digging further in, I took out the new IAC and bench tested both the old and new IAC valves. The old one was all gummed up with sticky carbon crap so it couldn't move freely, which I cleaned out with lots of carb spray and manual movement of the valve. Got it moving very freely. Then it bench tested properly.

    The new one I ordered for cheap failed the bench test. One side of the circuit didn't work at all. It would open but not close, which is a recipe for a high idle! So it's going back for a refund.

    Here's a GREAT article on how to test the valve so you KNOW whether it's the problem:

    https://www.toyotanation.com/threads...valve.1676205/

    Meanwhile, I re-installed the cleaned OE IAC. I also cleaned out the "T" junction clog with Qtips (very crapped up--see further up in this thread for details about this procedure) and then opened the other end (under the van) and blew out the coolant line with compressed air. While I had the throttle body out, I cleaned it thoroughly with carb spray as well.

    Reassembled everything, and the idle is perfect. In the end, the issue was the gummed-up IAC, which is partially dependent on the T-junction flow to function. So if you're having this problem, I would go straight to testing and cleaning the IAC, and cleaning the T junction.

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