Car Problem Reports

Mercury Mystique Problem With Idle Air Bypass Valve May Cause Engine Performance Problems

Mercury Mystique Problem
8 Reports
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Model Years Affected: 1999, 2000

Exhaust & Emissions Affected: 2.0L 4 Cylinder

Average Mileage: 157,809 mi (110,000 mi - 200,049 mi)


If you experience difficulty starting the engine when cold, stalling at idle, or hesitations during acceleration, it may be the idle air bypass valve. This valve helps the vehicle idle steady when the accelerator pedal is not pressed.

  • Visitor, , 130,000 mi

    I'm having problems with starting car in mornings. The car will crank but not turn over. I've brought the car to 2 different mechanics after repairs were made w/ new fuel pump, radiator fluid changed, new sensors, and finally a replaced air control valve. After the new valve the car ran fine for 3 days, and then the problem started all over again. The car runs fine & restarts great after it is warmed up. But, the mornings it will not start. I'm about ready to give up!

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  • Visitor, , 110,000 mi

    stalling, rough/erattic idel
    cleaned iac valve with carb cleaner

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