2018 Lincoln Navigator Has Rough Idle

Diagnosing the Causes of Rough Idle in Your 2018 Lincoln Navigator and How to Resolve Them

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Reviewed by
Andrew Hajjar
Written by RepairPal Car Genius
Updated January 14, 2025
0%
21% chance it's the
Spark Plugs
0%
15% chance it's the
Ignition Coil
0%
64% chance it's
Something else
The most common reasons a 2018 Lincoln Navigator has rough idle are a vacuum leak, an issue with the spark plugs, or a problem with the ignition coil.
  • Spark Plugs: Worn or fouled spark plugs can lead to misfires, poor fuel economy, and difficulty starting the engine.
  • Ignition Coil: A faulty ignition coil can cause misfires, rough idling, and difficulty starting the engine due to inadequate spark delivery to the spark plugs.
Proper diagnosis will determine the exact cause of your symptom, saving you money on unnecessary repairs. The diagnostic experts at RepairPal Certified shops have the right tools and experience to solve any symptom.

How much does it cost to fix a 2018 Lincoln Navigator has rough idle?

Common Repairs

The total repair cost will vary based on the condition of your vehicle and the number of repairs needed to fix your symptom. Proper diagnosis will save you money by finding the exact repairs needed to fix your car right the first time.

Brake caliper failure occurs in two different ways, and they create different symptoms.

The caliper can become stuck, in which case it won't release the brake pads. The seized caliper will cause the vehicle to brake constantly on one side, forcing the car to move toward that side. This pulling will be accompanied by a strong odor from one wheel.

Another way calipers fail is by leaking. If the caliper leaks, the brake pedal will feel too easy to push, and will sink all the way to the floor when held. Braking will become less effective the longer this goes on. There may also be brake fluid leaking onto the wheel.

Here are a few common symptoms of worn-out brake pads:

  1. Low brake pad warning light is on: Not all vehicles are equipped with this system, but if yours is, this dashboard indicator light will likely be the first signal it’s time to replace your brake pads.
  2. Brakes start to squeal regularly: This is often one of the first signs of worn brake pads and is caused by a metallic piece built into brake pads for this exact purpose. This part contacts the brake rotor to make a squealing or whining noise when the pads are low.
  3. Brakes make loud grinding noise: If not addressed early enough, your brake pads may get so worn that the metal backing plate of the pad grinds against the metal rotor.
  4. Brake pads look thin: You may be able to visually check your brake pad thickness to determine if they need replacement.

Brake rotors are mainly maintenance free, but when they have been subjected to abnormally hard use, the heat they absorb can cause the metal to turn blue, and cracking to occur. When this occurs, customers often specify they have lost braking power, or the vehicle's brakes are making noise. There may be no symptoms at all related to changing the brake rotors, since it is recommended to change brake rotors on most modern vehicles when performing a standard brake service.

Most often, a brake system inspection will just be a routine portion of manufacturer specified maintenance, and will be performed at mileage intervals. In those cases, there will likely be no symptoms. However, when a brake system makes a funny noise, causes vibration, is hard to use, will not slow the vehicle, prevents the vehicle from driving, makes the vehicle pull to one side, or leaks brake fluid, the vehicle will need a visit dedicated to the inspection of the brake system.

What are the steps to diagnose and fix a rough idle in a 2018 Lincoln Navigator?

To effectively diagnose and fix a rough idle in your 2018 Lincoln Navigator, start by checking for error codes using an OBD-II scanner, as this can quickly pinpoint any underlying issues. Next, inspect the spark plugs for wear or dirt, as faulty plugs can significantly impact engine performance. Don’t overlook the air filter; a clogged filter can restrict airflow and contribute to rough idling, so replace it if necessary. Additionally, examine the vacuum hoses for leaks or cracks, which can disrupt the air-fuel mixture. Moving on, assess the fuel system, including the fuel filter and injectors, to ensure they are functioning properly. Cleaning the throttle body is also crucial, as carbon buildup can hinder engine responsiveness. Finally, check for any exhaust restrictions that may affect performance and inspect the PCV valve for proper operation. If these steps do not resolve the issue, consider performing an idle relearn procedure to recalibrate the idle speed. By following this structured approach, you can effectively diagnose and address the rough idle in your vehicle.

What are the common problems that could cause a rough idle in a 2018 Lincoln Navigator?

When dealing with a rough idle in your 2018 Lincoln Navigator, it's essential to consider several common problems that could be affecting your vehicle's performance. One of the primary culprits is a dirty or clogged air filter, which can significantly restrict airflow to the engine, leading to an uneven idle. Additionally, faulty spark plugs are notorious for causing misfires; if they are worn out, they can disrupt the combustion process and result in a rough idle. Another issue to investigate is vacuum leaks, which can disturb the air-fuel mixture necessary for smooth engine operation. Fuel system problems, such as a clogged fuel filter or a malfunctioning fuel pump, can also impact engine performance and contribute to rough idling. Furthermore, a malfunctioning Mass Airflow Sensor (MAF) can cause the engine to run either too rich or too lean, exacerbating idle issues. Lastly, don't overlook the Exhaust Gas Recirculation (EGR) valve; if it's faulty, it can interfere with the combustion process, leading to rough idling. By understanding these common problems, you can take proactive steps to maintain your vehicle and address any issues that arise.

How urgent is it to address the rough idle in a 2018 Lincoln Navigator?

Addressing a rough idle in your 2018 Lincoln Navigator is not just a matter of comfort; it is crucial for the vehicle's overall health and safety. A rough idle can indicate underlying engine problems, such as faulty spark plugs or issues within the fuel system, which, if left unattended, may escalate into more severe complications. Ignoring these symptoms can lead to decreased fuel efficiency and engine misfires, ultimately resulting in costly repairs and potential engine damage. Moreover, a rough idle can compromise your vehicle's performance, making it less reliable on the road. Timely intervention through regular maintenance and repairs is essential to prevent these issues from worsening, ensuring that your Navigator remains safe and efficient for years to come. Therefore, it is imperative to address any signs of a rough idle promptly to safeguard your investment and maintain optimal driving conditions.

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