1999 Mercury Grand Marquis Problem Reports

RepairPal Verified 1999 Mercury Grand Marquis Problem Reports

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Bad spark plugs or an ignition coil can cause ignition misfire, which will illuminate the Check Engine Light.

A spring in the seat belt buckle may wear or fail, causing the airbag light on the instrument panel to illuminate. Failed buckles will require replacement.

The composite (plastic) intake manifold may crack near the thermostat housing and cause a coolant leak. Ford released an updated manifold that was reinforced to prevent a recurrence. No recall was issued for this problem but Ford did extend the warranty to seven years on some models from the date of purchase.

The throttle position sensor (TPS) may fail. Common symptoms of a defective TPS can be rough idle, hard starting, hesitation on acceleration, poor fuel economy, and stalling.

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.

An oil leak may develop from the the right side head gasket.  Oil from this type of leak will commonly drip onto the starter. Our technician tell us an updated head gasket is available to correct this concern.

The heater hose outlet may leak coolant at the back of the intake manifold. Sometimes this is misdiagnosed as a leaking intake manifold gasket because it resembles a leaking manifold.