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'02 Taurus rpm surge

Discussion in 'Ford Taurus' started by bradleyheathhays, Dec 6, 2017.

  1. bradleyheathhays

    bradleyheathhays New Member

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    Have an '02 Taurus 6 cyl where the startup and idle down seem normal, but when it's put in gear and allowed to move just with engine idle it has a consistent wave like throttle surge that can easily catch you off guard and propel you too far forward. The surge happens in pulses about a second and a half apart. After you get rolling above 5mph the surge either doesn't happen or isn't noticed. Does it at start up or after a long drive. Been happening for at least 5 years now.

    Any idea what's causing this?
  2. Dominick 1

    Dominick 1 Well-Known Member Respected Member

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    Welcome to the Forum
    Read this recall and see if it applies to you
    http://www.fordforumsonline.com/recalls/2002/taurus/362/
  3. Action

    Action Moderator Staff Member Respected Member

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    Welcome to the FFO!

    That scenario is called an idle roll or a warm idle roll. Typically what is happening is a condition that the PCM corrects and then stops and the condition repeats with correction and return to the issue. Unmetered air getting past the throttle body or a vacuum leak or some other lean or rich condition that is corrected and then the correction stops. To which the cycle repeats. The issue isn't great and goes unnoticed at higher engine RPMs because the issue does not impact the fuel air mixture that much with high volume of flow. When there is a smaller amount of air flow the leak is a greater percentage of the total fuel/air flow or charge and has an impact that can be felt.

    How many miles on the odometer?
    Has any one looked at it?
    Does outside temperature make a difference?

    >>>>>>>>>>>>>>Action
  4. bradleyheathhays

    bradleyheathhays New Member

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    Thanks to both you guys for the welcome.

    Dominick this car might be effected by the recall but I'm wary if a dealer wouldn't try to skirt out of diagnosing them. Is there a website somewhere where I can put the VIN number in and have it tell me if these recalls apply?

    Action, it sounds like you know exactly what's going on here.

    - There's about 78,000 on the odo but like said it's been happening for a while now. The vehicle has only been driven once or twice a week for a long time.

    - Don't think anyone professional has looked at the car for this specific issue.

    - Not sure if outside temp effects it or not. It's my Mother's car and this is the first time I've really investigated the problem.


    I'll be cleaning the throttle body and IAC today and see if that helps things any.
    Last edited: Dec 6, 2017
  5. Action

    Action Moderator Staff Member Respected Member

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    This is what you seek.
    https://owner.ford.com/tools/account/maintenance/recalls.html
    In a recall very little to no diagnosis is done. The (safety or emissions) recall only addresses the problem with safety or emissions that is out of compliance with federal laws.

    A clean throttle body and IAC is important. The IAC is what handles curb idle speed and is not a factor in any RPM higher than idle. The IAC is also controlled by the PCM. That PCM control is based on a variety of inputs from other sensors as to outside air temp, throttle position, coolant temp, barometric pressure, engine RPM and fuel burn sensed by O2 sensors.

    Low mileage older vehicles need to be maintained as well. Make sure the engine has clean air and fuel filters and a clean PCV. Keeping the fuel clean is a bit of an issue with the vehicle sitting for long periods of time. Then check for vacuum leaks and that all intake hoses (PCV) are connected. A hose that leaks or isn't fully connected allows unmetered air. The dynamic of unmetered air means the PCM gets confused as to what is happening because it isn't getting the whole story of air charge.

    >>>>>>>>>>>>Action
  6. bradleyheathhays

    bradleyheathhays New Member

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    Well, after cleaning the main throttle body just now I was going to clean the IAC valve but found this written on the outside... "Attention: Do not clean inside throttle body or adjust hard stop screw. Special coating on throttle plate and bore."

    Again, this was written on the small IAC attached just after the throttle body, although it seems to refer to the throttle body itself. So is this referring just to the smaller 'body' the IAC is installed in or does it refer to the main throttle body with the large pivoting circular flap valve?

    And whatever it's referring to, can I clean it despite this warning or should I follow the instruction?
  7. Action

    Action Moderator Staff Member Respected Member

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    Many techs disregard and clean anyway.

    Cleaning can remove some protective coating. The coating is there to prevent corrosion. Keeping a clean air filter will help with that as well. And cleaning it once may mean you need to clean it on a regular basis.

    >>>>>>>>Action
  8. bradleyheathhays

    bradleyheathhays New Member

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    That's good to hear, that people clean it anyway. Gave it a good drive and I'm almost ready to say the problem's cured. It was also doing some rough transitioning into first gear from a foot off the pedal coasting condition. That seems to be gone now too. Much more predictable.

    That's a real catch 22 on cleaning it though. I'd much rather brush it up once a year now rather than live with how it was driving before. I wonder what Ford expects you to do?
  9. Action

    Action Moderator Staff Member Respected Member

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    Replace it.

    >>>>>>>>>>>>Action

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