02 pontiac sport model erratic idle


Old 08-26-13, 07:15 AM
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Location: south carolina usa
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02 pontiac sport model erratic idle

Idle floats between 600 and 2100 rpm.
OB2 fault codes are 1635 and 1639 A1 and A2 respectively.
Computer internal problem?
If so avg cost?
Beautiful car with 224000 mi
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Old 08-26-13, 07:28 AM
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Likely a lot. There would seem to be a control unit failure of it is responding poorly to external conditions. It would take a mechanics diagnosis to actually put an estimate of cost together seeing all the issues that exist and that sometimes doesn't show everything until you get started into the car in depth. It is hard to know what all may be an issue as the computer diagnostic programs are limited especially in older cars. That mileage indicates there are a lot of possibilities but it could as well be a manifold vacuum leak causing the control module to go out of range to attempt to compensate for something else. A good evaluation should be done to be sure the car is worth the investment, I would start with a compression test to determine the soundness of the engine.
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