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Q: engine idle increases after shifting into park

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i have a 1992 ford explorer with 243000 miles on it. just recently, i have changed the oil and the spark plugs. i only take it for short drives of less than 10 miles. even on longer drives, i notice that after i come to a stop and shift into park, the idle climbs from around 700 rpm to between 1000 to 1500 rpm. could there be vacuum leaks that are causing the idle to spike like that? could a fuel filter change be needed since i do not know the last time it was done?

My car has 243000 miles.
My car has an automatic transmission.

You should first check for any vacuum leaks that would cause the engine to idle higher than normal. Even your idle in gear sound a little high. If no vacuum leaks are found in the intake or the brake booster, then you will need to check the PCV valve for sludge buildup keeping the valve in the open position.

If this is okay, then check the throttle plates and idle control valve for carbon build up that could be sticking them open causing the high idle. If you do not find the problem then contact a mechanic like one from YourMechanic to come and diagnose why your engine idle is high.

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