2001 Elantra 3,000 RPM Surge When Stopping

Discussion in 'Hyundai Elantra / Lantra' started by hc, Jul 13, 2009.

  1. hc

    hc Guest

    I own a 2001 Hyundai Elantra, bought used about a year ago. About 8
    months ago I noticed that about every 20 startups the RPM would surge to
    just under 3,000 RPM for just a second or so when I started the car.

    Then about 4 months ago the car developed a low-idle condition when
    warm, idling at about 500 RPM or so, just enough to make some vibration
    when idling at an intersection. No acceleration or stalling issues were
    present and the car otherwise continued to operate just fine. I used two
    tanks worth gas with fuel injector cleaner in each, plus throttle body
    cleaner, and gradually the low idle issue when away.

    About the time the low idle issue was resolved, however, the car began
    experiencing an RPM surge to just under 3,000 RPM for 3-4 seconds
    whenever I would let the clutch out as I was stopping the car. It does
    the RPM surge whether one is in 3rd, 2nd or 1st gear when the clutch is
    released, and the condition kicks in after about 1km of driving on the
    first trip of the day (on a warm day), and thereafter is evident on
    subsequent trips each day of the car has not cooled off significantly.

    The problem seems to be worsening such that when I let up on the gas
    when in motion and let out the clutch, the RPMs tend to stay at 2,000+
    briefly and then the RPM's settle down slowly, or the surge occurs as I
    stop, and then the RPM's settle quickly to around 2,000 RPM and then
    more slowly to normal idle. Once in a while the idle just stays at
    around 2,000 RPM. If I engage the clutch and move forward a bit in 1st
    gear, this usually settles the RPM down. And I can end the surge by
    getting under way in 1st gear as well. But the surge as I said will end
    on its own but not immediately.

    I wonder if anyone has any ideas on what the issue could be. I have
    sprayed the throttle linkage, clutch and brake cables under the engine
    hood and in the area of the pedals with WD40 in case it is a stuck
    cable, but no luck.

    About 8 weeks ago I changed the spark plugs and put new platinum plugs
    in. At that time the plugs showed no evidence that would suggested any
    problem with any of the cylinders. This was when the low idle issue was
    present and the plug change did not help the low idle issue.

    I am wondering as well whether I should remove the sensors in the
    throttle body and clean them, perhaps they clogged after the throttle
    body cleaner was applied. Is this a possibility?

    Many thanks for any suggestions that may be offered as what this problem
    could be.

    London, Ontario, Canada
    hc, Jul 13, 2009
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  2. hc

    Mr. Smith Guest

    Check all you vaccuum hoses. I had a problem similiar to this. While
    having my brakes worked on the mechanic noticed a bad hose, replaced
    it and the problem went away. Total cost of repair for that problem
    under $5.
    Mr. Smith, Jul 14, 2009
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  3. hc

    hyundaitech Guest

    There may be a reprogram to correct this. On U.S. models, there's a
    reprogram to correct excessive RPMs which occur when depressing and
    releasing the clutch pedal.

    You may also have an intermittent poor contact in your throttle
    position sensor. This was a common problem in 2001-2002 models.
    hyundaitech, Jul 15, 2009
  4. hc

    hc Guest

    Thanks for the tip and also thanks to the other person who suggested I
    check for a vacuum hose issue. I connected an Innova 31a OBD-II code
    reader to the car and it shows code "P021 (Throttle Position Sensor
    Range/Performance" as the only set trouble code. I am wondering if this
    code being set is a definitive indication of the TPS being the fault.
    The Haynes manual says to measure the OHMs across terminals 2-3 and says
    that the value should be in the range stated by the Haynes manual with
    the throttle plate closed. The manual gives a value between 900 and
    3,000 ohms, but it's not clear if that range is for the connection
    between terminals 1-3 or for the variable value when one connects to
    terminals 1 and 3. A further problem is that my car uses a different
    connector from the manual and identifying terminal 1 is difficult. Here
    are the measured values assuming terminal 1 is the top terminal and that
    3 is the lowest (the connector is vertically mounted):

    Pins measured as follows, top to bottom:

    Resistance with closed throttle (engine off) between 1 and 2: 1900 Ohms
    Resistance with closed throttle (engine off) between 2 and 3: 900 Ohms

    The Haynes manual says to measure the value between 2 and 3, but as I
    noted I am not sure whether Pin 1 is at the top or the bottom, so one of
    the above measurements will be the measurement wanted by the Haynes manual.

    Resistance (engine off) between 1 and 3 from closed to open: 2600-1100
    Ohms. This is a measurement that the Haynes manual says to test for, but
    only in terms of seeing whether the resistance changes smoothly, which
    it appears to, across the range stated.

    Any help interpreting the above values would be appreciated.

    London, Ontario, Canada
    hc, Jul 19, 2009
  5. hc

    hyundaitech Guest

    P0021 indicates a likely problem with the TPS. Check your PCV hose to
    be sure it doesn't have a hole in it.
    hyundaitech, Jul 26, 2009
  6. hc

    hyundaitech Guest

    Sorry. Make that P0121. I presume that's the actual code you have.
    hyundaitech, Jul 27, 2009
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