2002 mercury mystique vacuum leak - Mercury Cars & Trucks

Have the power brake booster checked, it may have a vacuum leak in the booster diaphragm or a defective brake booster vacuum check valve.

you can buy the filler part for that 99 mercury mystique

Fuel Tank Filler Neck

The idle is controlled by the engine computer through the idle air control valve. This valve will be mounted on the throttle body assembly-where the big air boot from air filter attaches. This valve can get deposits built up, restricting idle air flow to the engine. Take it off and clean it, and the air passages it sits over. Be looking also for a vacuum or air leak. Check the ends of the vacuum hoses for splitting or cracks that leak.

• Bank 1 sensor 1 O2 Sensor. Also with this or they are very known for an intake gasket leak. Make sure to check your vacuum hoses first.
• First check for vacuum leak from a hose. If none are found switch that top O2 Sensor (upstream) If this persists after all that you may have an intake vacuum leak.

Regards, Tony

computer cars r complicated-u cud hav a vacuum leak that doesnt show code--may need to clean some injectors-inner ones--how r the plug wires they wear internally as well as coil--maybe du another scan-ur ride is 16yrs

that is a breathing vent tube like a rain gutter down spout. nothing to worry about

first thing is to check for any split vacuum hoses that are leaking, then clean throtle body with cleaner,(thrtle body cleaner) if this has no affect then replace the idle air control valve, hope this helps.

a vacuum leak on the engine somewhere can cause this symptom

Very common for Ford/Mercury trannys. Do you have the 4.6 L in this car by chance?
The tranny will have to be rebuilt. There is most likely syncro or other part of the tranny, which there are several, that could be causing this. The tranny will have to have a thurough look-through. If you have a vacuum operated actuator on the outside of this tranny, it wouldn't hurt to check for leaks. Also a VERY good idea to change your tranny fluid and filter on any vehicle every 30,000 miles.

Check for vacuum leaks.You can spray starting fluid around all parts of the intake.Observe idle as you do.If there is a leak the engine rpm will race higher.Also listen for hissing noise.Is the check engine light on?..If so what codes are stored..Good Luck!!!