Edmunds Answers

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  • avatar zaken1 12/02/11 12:35 am PST

    The idle RPM is not adjusted with the TPS. It is largely independent of the throttle position; and is automatically set by the computer; by integrating information from many different inputs, and using that data to adjust the idle speed by varying the position of the idle air control valve. The main function of the TPS is to tell the computer when the throttle is opened beyond the idle position; when it is wide open, and when it is shut.

    In order to properly set the TPS position; the cylinder compression must be within manufacturer's specifications and the spark plugs must be clean and in good condition. The ignition timing must first be set to manufacturer's specifications, It is important to temporarily disable the electronic spark timing circuit while the ignition timing is checked and adjusted. It is also important that the factory throttle cable stop position has not been disturbed; as that would make it far more difficult to set the TPS.
    The TPS is adjusted by moving its position, in reponse to voltage readings from the computer. This requires a digital vvoltmeter which can read to a hundredth of a volt. The specific procedure is described in the service manual for this particular model. If you do not now have access to a service manual; you can get a week of online access to the most accurate and complete professional grade service data for this vehicle for about $12 by going to (http://www.eautorepair.net/Marketing/De
    fault.asp
    ).
    If the compression and plugs are in good shape; and the throttle stop and ignition timing have not been messsed up; it is also possible to set the TPS position by the way the car runs. Start by placing the sensor where its mounting bolts are in the center of their slots; and see how it runs in that position. This is a very sensitive adjustment; so only move the sensor in small amounts; until you get a feeling for the amount of change moving it produces. If the motor seems to hestate and run too lean on acceleration; turn the sensor in the opposite direction to the way the throttle linkage moves when the accelerator pedal is pressed down. If the motor runs too rich; turn the sensor in the same direction that the throttle moves when it opens. When it is set right; the motor should respond well on acceleration; and you should be able to feel the fuel cut off on decelleration; and then cut back in when the vehicle speed drops to less than about 15 mph. If the sensor is set too far in the rich direction; the fuel will not cut off on deceleration. If the sensor is set too lean; there will be a flat spot in response when beginning to accelerate after slowing down.
    With patience and care, this setting can make the car run very well.

Answers

  • zaken1 12/02/11 12:35 am PST

    The idle RPM is not adjusted with the TPS. It is largely independent of the throttle position; and is automatically set by the computer; by integrating information from many different inputs, and using that data to adjust the idle speed by varying the position of the idle air control valve. The main function of the TPS is to tell the computer when the throttle is opened beyond the idle position; when it is wide open, and when it is shut.

    In order to properly set the TPS position; the cylinder compression must be within manufacturer's specifications and the spark plugs must be clean and in good condition. The ignition timing must first be set to manufacturer's specifications, It is important to temporarily disable the electronic spark timing circuit while the ignition timing is checked and adjusted. It is also important that the factory throttle cable stop position has not been disturbed; as that would make it far more difficult to set the TPS.
    The TPS is adjusted by moving its position, in reponse to voltage readings from the computer. This requires a digital vvoltmeter which can read to a hundredth of a volt. The specific procedure is described in the service manual for this particular model. If you do not now have access to a service manual; you can get a week of online access to the most accurate and complete professional grade service data for this vehicle for about $12 by going to (http://www.eautorepair.net/Marketing/De
    fault.asp
    ).
    If the compression and plugs are in good shape; and the throttle stop and ignition timing have not been messsed up; it is also possible to set the TPS position by the way the car runs. Start by placing the sensor where its mounting bolts are in the center of their slots; and see how it runs in that position. This is a very sensitive adjustment; so only move the sensor in small amounts; until you get a feeling for the amount of change moving it produces. If the motor seems to hestate and run too lean on acceleration; turn the sensor in the opposite direction to the way the throttle linkage moves when the accelerator pedal is pressed down. If the motor runs too rich; turn the sensor in the same direction that the throttle moves when it opens. When it is set right; the motor should respond well on acceleration; and you should be able to feel the fuel cut off on decelleration; and then cut back in when the vehicle speed drops to less than about 15 mph. If the sensor is set too far in the rich direction; the fuel will not cut off on deceleration. If the sensor is set too lean; there will be a flat spot in response when beginning to accelerate after slowing down.
    With patience and care, this setting can make the car run very well.

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