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Mercury Grand Marquis Rough Idle

Learn if it's a simple fix or time to seek out a trusted technician.

What are common reasons my Mercury Grand Marquis has a rough idle?

While there are a variety of reasons your Mercury Grand Marquis has a rough idle, the most common 3 are a vacuum leak, an issue with the spark plugs, or a problem with the ignition coil.
34%
of the time it's
Vacuum Leak
21%
of the time it's
Spark Plugs
15%
of the time it's
Ignition Coil

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Related Mercury Grand Marquis Questions

See what others are asking about their Mercury Grand Marquis. Get answers from RepairPal's community of auto experts and enthusiasts.
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Related Mercury Grand Marquis Problems

Find the most common driver-reported problems that are to blame when a Mercury Grand Marquis has a rough idle.
The throttle position sensor (tps) may fail. common symptoms of a defective tps can be rough idle, hard starting, he...
Bad spark plugs or an ignition coil can cause ignition misfire, which will illuminate the check engine light.
Mercury Grand Marquis Repairs and Prices
All costs based on RepairPal Fair Price Estimate™ averages. Actual prices may change depending on final diagnosis.

Mercury Grand Marquis Rough Idle Repair Symptoms

A failing ignition coil will create misfires in the engine, and lead to hesitation, extreme power loss, engine stalling, poor fuel mileage, and illumination of the check engine ...Read More
As we discussed, spark plugs are necessary for any gasoline engine to run. When they fail, the engine is in a constant state of attempting to ignite air and fuel, but cannot. Th...Read More