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Thread: '97 Previa RWD VERY HIGH IDLE Warm Engine

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    '97 Previa RWD VERY HIGH IDLE Warm Engine

    Greetings Forum,
    Just bought a '97 Previa RWD, 101K miles. On cold start idle seems normal (slightly fast idle). One warm, in neutral, idle is VERY HIGH. Van does not have guage but I would over 2000 RPM. When I try to blip the accelerator, it idles even faster. I see no obvious leaks or cracks in any hoses under the hood or at driver's seat access panel. The throttle cables move very freely. If I put it Neutral while coasting the idle goes up and down until van comes to a stop, then high idle is back. Any ideas on possible causes would be very appreciated.
    Thanks,
    Steve
    CT/USA

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    Re: '97 Previa RWD VERY HIGH IDLE Warm Engine

    Forgot to mention...other than high idle, van performs very well.

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    Re: '97 Previa RWD VERY HIGH IDLE Warm Engine

    remove the throttle body and then remove the idle air controller... clean both parts.... carbon buildup will prevent them from working properly
    check the A/C idle up valve also.... it is connected to a 5/8" rubber hose that runs a few inches away from the throttle body, closer to the starter... those things tend to get sticky also from carbon build up

    some brute forcing is necessary to take out the throttle body... it took me about 2 hours to do it because of little room and so much crap in the way


    you will need a JIS crosshead screwdriver to remove the IAC screws frustration free, if you mistakenly use a phillips screwdriver on them, you will damage the screw head and it will not come out





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    Re: '97 Previa RWD VERY HIGH IDLE Warm Engine

    Thanks TM, I haven't experienced this problem yet so I'm glad you posted. Nice pics. Tim

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    Re: '97 Previa RWD VERY HIGH IDLE Warm Engine

    Thanks so much for the very detailed info and photos! I will try this and report.

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    Van Enthusiast tbkilb01's Avatar
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    Thumbs up Re: '97 Previa RWD VERY HIGH IDLE Warm Engine

    My 92 previa is suffering that same very high idle after doing head gasket. I decided to do the throttle thingy before hitting the road seriously..and well ran into a rubber o/ring type gasket butting up to idle air controller and so..does the o- ring gasket for the idle air controller need to be replaced? any part numbers out there? just finished throttle body and made gasket from felpro material but leary about rubber gasket stuck in throttle body... i havent damaged it-did best to steer away from it till i figure that out..,yea a good 2 hours to remove throttle body is right...taking off with drop light to boot! the screws were hard to get off allright. I filed down PHILLIPS to mimic JIS. Worked great. Really wicked build up in there is right. I used a toothbrush and fingers for a good hour cleaning but i found one hole near intake on right side really clogged with a chunk of black carbon plugging it up.. letting spot soak so i can chip it out. seems the more i clean more the more comes out? not sure where it leads but its there, looked for the thread on it but WOW its evading me. i recall someome saying the used a allen wrench? yea you right theres a ton of hoses all in good shape though. waiting for some info before reinstalling.
    Last edited by tbkilb01; 02-15-2015 at 07:27 PM.

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    Re: '97 Previa RWD VERY HIGH IDLE Warm Engine

    you will need to buy the proper gaskets for the throttle body and idle air controller from the dealer
    I went ahead and replaced the screws in mine and good thing I got them ahead of them because I knew one of them would strip! That was back before I knew anything about JIS screws lol

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

    thanks TheMan,
    i found number on previous posting
    here at this terrific forum.
    toyopartmotors had them cheap enough
    needed a few other small hard to find plastic parts
    to make the $11 shipping worth while.
    still wondering about that upper roller part (68310) of side door
    but i think ill use tims trick later after tackling this throttle/idle thingy
    any advice on plugged up hole on intake?
    thinking recirculating line? havent traced it
    i m still cleaning on the spot. its quite a build up...
    tough spot... has me wanting to investigate further.
    Attached Images Attached Images
    Last edited by tbkilb01; 02-21-2015 at 08:45 PM.

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    Re: '97 Previa RWD VERY HIGH IDLE Warm Engine

    The port hole seems it leads to EGR VALVE...to
    recirculate exhaust gases to intake manifold
    to lower max combustion temperature.
    wonder if buildup contributed to my HG failure...humm?
    cleaning of EGR MODULATOR is part of inspection.pretty simple...
    i finished cleaning port hole.. got best results using an old meat hook
    i used years ago in meat business.
    It has the perfect angle to "hook" around and reach into hole.
    Carb cleaner melted it eventually...patience.
    Attached Images Attached Images
    Last edited by tbkilb01; 02-15-2015 at 07:30 PM.

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    Re: '97 Previa RWD VERY HIGH IDLE Warm Engine

    it could be EGR, but it could very much also be oil due to faulty PCV valve or bad piston rings... my EGR valve was shot and the oil made a mess in the throttle body

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    Re: '97 Previa RWD VERY HIGH IDLE Warm Engine

    thanks, well i finished cleaning up throttle body and
    dug out lump of build up in intake, found several threads
    on it...cleaned up and tested ISC valve. it was crusty with rusty
    I felt so good about it that i installed it and well the previa still
    has that high idle.

    guess i be takings off the throttle body again (pretty simple
    especially after I cleaned up the area that really needed cleaning) to test TPS
    (and BVSV) and reset it on throttle. i found Tims video on photobucket...
    I'm hoping its not the EGR...ITS IN A TOUGH SPOT! and rather costly to just take a chance
    on. Not too many used/parts previas this part of LA. not to mention one pick your parts.
    i replaced PCV valve just cause, cleaned EGR Vacuum modulator, it was easy considering
    the postion on previa.
    Following the FSM flow chart for high idle, just not getting lucky?
    ..no codes popping up either.
    I had van since new and I just can't wait to get back on the road again. Time
    for a ROAD TRIP!

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    Re: '97 Previa RWD VERY HIGH IDLE Warm Engine

    on the S/C, the throttle body is under the hood... did you actually remove that one and clean it?

  13. #13
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    Re: '97 Previa RWD VERY HIGH IDLE Warm Engine

    Might be a long shot, but I'd check the coolant temperature sensor.

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    Re: '97 Previa RWD VERY HIGH IDLE Warm Engine

    thanks TheMan, and yes I'm still tackling that high idle after HG replacement... followed your threads and Timsrv's, even searched out toyotanation, Zen and a few others and i tell you...you two are legends! anywho, i found that big lump in intake and took care of it and felt that was the problem, so i cleaned throttle and replaced, boy was i mistaken DOH!!! I just didn't listen!!! so i dug out the old FSM and following the troubleshooting chart for high idle. it could be exhaust system (EGR etc. ) but im going to finish EFI SYSTEM check. then move on to EGR even if I get to bottom of problem (TPS etc. ) i have the PB Blaster working on EGR connections and I'm wondering if the crowfoot needed is 15/16 or 1" to remove the nut since its in a very difficult spot as engine is in car... ive read two different threads and each differs. i think they were for S/C or 80's toy van..I found both sizes (and theyre not cheap)on EBAY but have not ordered for that reason....i did do modulator just cuz it was EZ. it was okay. seems everything I test with multimeter so far is good... guess its blockage? (but I 've yet to test TPS OR BVSV). Is the passage from intake to EGR able to be cleaned? ( in picture) thats where the build up i found in intake came through after all these years..i can remove other end of recirculation tube by exhaust manifold and clear it out pretty EZ. I had to remove it to do HG.
    Attached Images Attached Images
    Last edited by tbkilb01; 02-21-2015 at 08:41 PM. Reason: pictures

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    Re: '97 Previa RWD VERY HIGH IDLE Warm Engine

    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...?
    Attached Images Attached Images
    Last edited by tbkilb01; 02-21-2015 at 08:44 PM.

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    Re: '97 Previa RWD VERY HIGH IDLE Warm Engine

    maybe it's for the transmission?

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    Re: '97 Previa RWD VERY HIGH IDLE Warm Engine

    yea you could be right...trany does wait till prev warms up to shift to high most mornings less I let it really warm up before driving it. Ill check in transmission section of FSM..
    looks like weather warming and drying for a spell, so I can get back to TPS/BVSV...
    any clue what size crowfoot i need to remove EGR?

    I just found what third sensor is. I ran across it in FSM today. Its a START TEMPERATURE TIME SWITCHimage.jpg
    Last edited by tbkilb01; 03-13-2015 at 07:56 PM.

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    Re: '97 Previa RWD VERY HIGH IDLE Warm Engine

    Well, at least you've ruled it out!
    I've no experience with the SC engine, and I gather that few of us on this list do. So you're a pioneer in diagnosing problems like you're describing.
    My experience with the coolant temperature sensor was one where I had no idle, rather than a fast one. But I learned that the CPU looks to it to control the ISC, and I suppose that the sensor might fail in different ways. Anyway, I figured it was a long shot.
    Keep at it! We all stand to gain from your experience!

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    Re: '97 Previa RWD VERY HIGH IDLE Warm Engine

    I've cleaned out throttle body
    of my 92 previa NA also
    replaced TPS,
    checked BVSV,
    replaced EGR modulator,
    and cleaned ISC valve
    and still have the high idle...
    Prev just doesn't idle down...after warming up (I think).
    next on the list in FSM is to check the A/C VSV and power steering air valve for leaks.
    Then the fuel pressure regulator and
    then off to cold start injector and injectors
    maybe I set injectors in wrong after doing HG?
    Seems I would've solved issue by now?

    Think I'll just retrace vacuum hoses, never had
    the FAST IDLE before Head Gasket repair
    Last edited by tbkilb01; 02-19-2015 at 01:20 PM. Reason: Second thoughts

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    Re: '97 Previa RWD VERY HIGH IDLE Warm Engine

    COULD IT BE?My 92 previa finally calmed down!
    I was waiting to persue checking A/C and POWER STEERING
    IDLE UP VALVES when I decided to fix a leaky EXHAUST LEAK
    that magically appeared after doing the HG. (I guess I pushed too hard on exhaust
    in attempt to move out of my way). I found pieces of aged and cracked up
    gasket fragments leftover in MANIFOLD to CAT connection. Replaced gaskets and
    fired her up and she just PURRS!! GO FIGURE? well she got a good thorough much needed
    work over. Its definitey time for a ROAD TRIP...! Sure feels GREAT.

    P.S.
    I never did get EGR VALVE off... I purchased 15/16 and 1" crowfoot wrenches
    on Ebay and the first one was too small, and the latter was too big..Go figure!
    Its probably a 25 mm .. but hey I'll let it be...
    not broke, not tinker with...

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