Idle control Valve?

Discussion in 'General Motoring' started by danielr, Mar 9, 2010.

  1. danielr

    danielr Guest

    Before I start describing the problem, I’ll beg for your patience:
    1997 SL SOHC, 186600 Km, standard transmission; in Toronto (Canada)
    weather; and I love this car.
    Last December, engine was having high idling speed (1550 to 2000 rpm)
    when stopping at traffic lights, slowly coming down to its normal
    (approx. 700-900 rpm) after 4-5 seconds.
    As Emission Test was near, and this symptom had been identified in
    this forum as defective Idle Control Valve, (fearing that this idling
    could hamper passing the test), I made the decision to request my
    mechanic to replace it.
    After he replaced it, the car would not start; so he restored the old
    one, and the high idling rpm “seemed” to disappear,
    But a new problem appeared:
    ERRATIC startup (here is where the request for your patience comes
    There is NO PROBLEM to startup:
    a) In the morning,
    b) When the engine has been OFF less than 30 – 45 minutes, or
    c) More than 1.5 (one and half) hour.
    The problem appears when engine has been OFF for about one hour.
    Then, the engine cranks (what I believe is indicative of battery OK),
    but no starting.
    I suspect it is something related to fuel system; and the scenario is
    further complicated because the failure seems more frequent when the
    gas tank is below ¼ of full (approx 10 liters).
    So, my questions are (provided my assumption of fuel system is
    Is it there any VERY SPECIAL precaution in removing / mounting /
    exchanging the ICV?
    Is it possible that other factor is provoking this failure?
    I want to have this problem solved, as I fear it may impact the
    integrity of the starter motor.
    Your ideas / suggestions / corrections will be very much appreciated

    danielr, Mar 9, 2010
  2. danielr

    Oppie Guest

    When did you replace the fuel filter last?
    Did you use any 'drygas' to remove water in the fuel system? Water will plug
    the fuel filter.
    Do you get fuel pressure at key on?
    Do you get fuel delivery (measured with a bleeder at the fuel test port)
    during cranking?
    If the car has a crank angle sensor, have it checked.
    Defective coolant temperature sensors (CTS) and EGR valve leakage will all
    contribute to high idle RPM. Consider that while the idle air solenoid (IAS)
    was being changed, a flaky harness was disturbed. Check for abraded wires
    and corrosion on the connectors.
    Grounds, Grounds, Grounds! Older cars have a propensity for loosing good
    chassis ground connections. The cranking current (about 300 Amps) can upset
    things if there is a flaky ground somewhere.

    '01 lw300
    Oppie, Mar 10, 2010
  3. danielr

    Private Guest

    I agree with all Oppie said but especially that poor chassis ground
    connections can cause all sorts of strange and difficult to diagnose and
    explain problems, many of which can be intermitant and temp or weather
    dependant. IMHO a COMPLETE cleaning of ALL chassis ground connections is
    one of the most important preventative maintenance operations that should be
    performed on all vehicles and should be the first task when looking for the
    cause of ANY electrical problem.

    Saturn S series cars have several chassis grounds, IIRC there are 2 on the
    engine rear above the clutch housing (IIRC the engine rear bolts require a
    deep socket and probably significant force to break free due to probable
    galvanic corrosion inside the engine block, which may be the cause of poor
    electrical connection, use anti-seize on threads when reassembling) and 2 or
    3? located on the left inner fender body sheet metal at least 1 of which
    IIRC requires the removal of the battery tray for access. All of these
    connections should be disassembled, cleaned (small wire brush &
    sandpaper)and IMHO greased to prevent or retard further corrosion. I use
    any coppercoat anti-seize thread compound as the anti corrosion grease, but
    any grease should work. This job will take 1-2 hours to complete properly
    but requires only basic tools and can be scheduled for a sunny warm and dry
    day and easily combined with an oil change. Both jobs can easily be
    completed by any driveway mechanic.

    Good luck, YMMV
    Private, Mar 10, 2010
  4. danielr

    dondjn Guest

    I had something very simular to your problem with the fast idle but it
    did not affect starting.
    I found a large split in the large vacumn line that comes off the top
    of the valve cover and goes
    down behind engine. Fixed that and the problem went away . . . .
    dondjn, Mar 10, 2010
  5. danielr

    Oppie Guest

    Good point. Similarly, the EGR is a calibrated vacuum leak and is
    compensated for. If the EGR valve sticks open, depending on the type of
    valve (some incorporate a position feedback), the manifold vacuum goes to

    Some engine management systems have a manifold vacuum sensor that looks for
    a certain level of vacuum during cranking in order to self test. It has to
    pass this test before injectors are enabled. On my lw300, it has to crank at
    least a half second before it will catch. I have had other EFI cars that
    (especially when hot) would kick over on the first revolution of cranking.

    But I digress... If you have one of those cars that does a self test before
    enabling fuel injection, any vacuum leak may be inhibiting the starting. If
    it's marginal, it may start and idle high.
    You can pinch the vacuum lines while the engine is running and see if the
    RPM changes. Also a vacuum gauge applied to the manifold port should read at
    least 20" and steady on idle.

    If you haven't changed the PCV valve, do it. It too is a calibrated vacuum
    leak and if the pintle sticks open, will bypass too much air.

    If all else fails, have the catalytic converter and muffler checked for
    backpressure. Not unheard of for an older car to shatter the honeycomb
    structure inside the cat converter and wind up plugging the muffler. This
    would also give you limited power for acceleration.
    Oppie, Mar 11, 2010
  6. danielr

    danielr Guest

    To ALL;

    Thank you VERY MUCH for your comments, hints and recommendations.
    I will discuss them with my mechanic, and will keep you informed of
    future developments,
    BTW; I systematically change the PCV valve before the emission test.
    Peharps, this last I installed is faulty. Will replace it and shall
    see results.

    Thanks again.

    danielr, Mar 12, 2010
  7. danielr

    teichholtz Guest

    danielr wrote:
    About 20 years ago I had a 1978 BWM 320i. It started exhibiting a very
    similar symptom. The interesting thing was that the 1 hour + translated
    to going to dinner with a family member. If I went to work, car sat for
    8+ hours. If I was doing errands, usually less than one hour. On a
    date, usually over an hour and a half. But in one month when my sister
    and then a couple of weeks, brother, came to town, the car would not
    start after dinner.

    The problem was the fuse for the fuel pump. It was slightly corroded
    and at a certain temp would not make a proper connection. Apparently
    the hour was enough for it to cool down to the point where the
    connection was bad.

    A piece of emery cloth to polish up the ends and the problem went away.
    teichholtz, Mar 13, 2010
  8. danielr

    danielr Guest

    hello everyone;
    i discussed the post and your answers with my mechanic.
    he lifted the hood to have a look at the ICV area, and showed me a
    leak in the fuel system.
    there is a black bakelite right angle which couples from a rubber hose
    into the (apparently aluminum) front interface of the fuel rail (looks
    as a manifold and runs behind the SOHC engine block, delivering the
    fuel into the cylinders).
    IT IS WET.
    we ignore if what is leaking is the bakelite-aluminum interface, or
    the bakelite-rubber interface.
    he says that the best would be to CHANGE to whole fuel (manifold) rail
    (C$ 350 + labor). because a coupling bakelite-aluminum is flimsy and
    could be location of the leak. he did not touch it, nor explore the
    the part must come from USA location.
    a personal note:
    speaking as an (ex) design engineer (i am retired now), my duty was 5%
    inspiration and (compulsory) 95% perspiration, to deal with the
    frustrating task of fixing / improving the (first pass of) design to
    make it work.
    apparently, for this mechanic is more cost effective to replace
    instead of researching to fix. i would not oppose to replace unless IT
    searching the web for fuel rails for saturn, led me to stores/
    warehouses which offer
    “MR GASKET PUSH ON RUBBER HOSE, BLACK -- -8 AN, 4 ' Long, Designed To
    Be Used With Mr. Gasket Push-On Swivel Fittings, Can Withstand Up To
    250 PSI”; for U$S 23.00…………
    it is only the hose, but gives an idea of possinle alternatives once
    the REAL ROOT CAUSE of the problem is located.
    so, my new questions are:
    a) as there were previous replies mentioning drop of pressure in fuel
    system as possible culprit of the erratic startup problem, is it
    possible that this leak to be the cause of it?
    b) i don’t know the designation of THAT black aluminum angle, neither
    if it is a coupler between the rubber hose OR the front end (affixed
    to) the fuel rail manifold; so i can not seek it online.
    all suggestions, references, comments, advices will be greatly

    danielr, Mar 22, 2010
  9. danielr

    Oppie Guest

    Hello fellow design engineer (I'm an EE).

    I would get another opinion. Yes, the fuel leak has to be fixed but whether
    replacing a whole assembly instead of doing an appropriate minimal fix has
    to be evaluated. Besides, 'wet' will not likely be your root cause.
    I had Saturn try to find out why my L300 wouldn't start. Turned out to be
    an intermittent crank sensor but they surely charged me for a very minor
    leak in the fuel test port (which did not leak when the safety cap was on).
    I had damaged the schrader valve when attaching a makeshift fuel pressure
    Point is that lots of techs go for the obvious rather than looking for root
    Oppie, Mar 23, 2010
  10. danielr

    danielr Guest

    Hi Oppie;

    Thank you very much for your insight.
    I am in the process of getting "that second" opinion, and get the leak
    I am trying to to avoid (as much as possible), going to the dealer
    Here in Canada, they are extremely expensive.
    danielr, Mar 25, 2010
  11. danielr

    Oppie Guest

    I've been considering again getting the Autotap tool. Had considered getting
    this a few years back but didn't have a laptop at the time.
    Just got an email from autotap telling of their new product. Looks to be
    the same hardware but an entirely new software package.
    For $200 and if you have a laptop, there is some impressive diagnostic
    ability. Not just a code reader but can read and display all the engine and
    BCM data. ABS and transmission codes are not supported (which is not a deal
    breaker but I'm not happy). Other thing is that aside from resetting the
    Check Engine Light, it's a read only device; you can't change any program
    values or exercise solenoids. Still, the data you can read a wealth of data.

    Good Luck,
    White Plains, NY USA
    Oppie, Mar 28, 2010
  12. danielr

    danielr Guest

    Last Monday I took the car to this "second opinion mechanic".
    He fixed the leak; extracted the black bakelite elbow, and readjusted
    its fit. He noticed that EGR valve looked relatively new (it was
    actually changed October last year, after repeatedly SES notices and
    P0404 DTCs), mentioned that probably, when they changed the EGR
    somehow might have banged into that coupling. There is an O ring
    inside which perhaps was not fitting well.
    When trying to start up, IT DIDN’T.
    He put his (professional) ODB scanner, which reported DTC 1599.
    Checked spark into plugs, and here wasn’t. He indicated that it could
    be crankshaft position sensor [CPS], or the ignition module or the
    By then, I left to have him working without me scooping around over
    his shoulder (I believe it is very annoying for some people, and
    didn’t want to take the risk).
    Something he mentioned: He said Saturn was an invention from GM to
    confront Japanese penetrating USA markets. Then, they put together
    (IIRC) a Suzuki engine with some other GM not too vital parts (I don't
    remember the tranny make he mentioned), and the plastic body. I am
    mentioning this because he expressed his confidence with confronting
    the problem based in his familiarity with GM “automotive
    architecture”, and the possibility of swapping parts rescued from some
    other scrapped GM cars (BTW, he showed me his stock of EGR valves
    rescued from other “deceased”).
    Furthermore, he has the Mitchell Database System, with all manuals
    data accessible in his PC.
    Phone call Tuesday: He had tried another CPS, but no luck; next, he
    had asked to borrow an ignition module from a friend, and was awaiting
    for it.
    Phone call Thursday: No luck with module. Was checking for corroded
    connections into the PCM (computer); mostly because when connecting
    the OBD scanner, it displays 63 RPM even is the key has not been
    turned to turn on. He says that are generally about 300 RPM during
    initial crank.
    As a retired EE, I saw my good quote of anomalies originated from
    spurious charges that get stored in some (not properly terminated or
    loosely connected) ports in CMOS technology devices (I believe that
    must be the technology of this PCM). These devils are, usually, very
    temperamental and temperature, moisture, shock (and you name it)
    If all checked connections are OK, them we’ll have to conclude that it
    might be the PCM.
    He says it’s difficult to get another used one to swap, first because
    my car is standard, and second because Saturn is history, and few cars
    available nowadays.
    Next phone call will be tomorrow, we’ll go from there.
    YES, I have my fingers crossed!!!!!!!!

    danielr, Apr 4, 2010
  13. danielr

    danielr Guest


    Car Fixed:
    Before categorically blaming the PCM, this mechanic checked all
    electric circuits leading to PCM, but found none deemed to be the
    culprit. Lastly, replaced the Crankshaft Position Sensor for another
    used one.
    Before leaving this posting, I want to express my appreciation to all
    those who contributed with their comments and suggestions.
    Best regards.

    danielr, Apr 7, 2010
  14. danielr

    Oppie Guest

    Glad to hear you finally got a fix!

    The Crank sensor, while it has diagnostic codes associated with it, rarely
    seems to throw those codes when it becomes defective. It is the 'master'
    timing element for all power train controls. When it gets flaky, it's more
    likely to cause all sorts of 'phantom' codes that are totally unrelated to
    the crank sensor. As I understand it, the sensor is a magnetically biased
    coil that senses ferrous gear teeth on the crankshaft. Crank has a nominal
    36 tooth pattern with one tooth missing to indicate TDC. PCM does a clock
    regeneration and missing pulse detection to detect shaft position. (as a
    fellow EE, you should appreciate that...)
    Best Regards - Oppie
    Oppie, Apr 8, 2010
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