2014 GMC Terrain Has Rough Idle

Troubleshooting Causes of Rough Idle in Your 2014 GMC Terrain and How to Resolve Them

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Reviewed by
Devin Cabugcal
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 2014 GMC Terrain 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 2014 GMC Terrain 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.

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.

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 initial diagnostic steps to take for a rough idle in a 2014 GMC Terrain?

When faced with a rough idle in your 2014 GMC Terrain, the first step is to check for fault codes using an OBD-II scanner, as these codes can reveal critical information about potential engine issues. Next, inspect the spark plugs for wear or fouling, as damaged plugs can lead to misfires that contribute to an unstable idle. Additionally, examine the air filter; a clogged filter can restrict airflow, negatively impacting engine performance. It's also important to inspect vacuum hoses for any cracks or disconnections, as leaks can disrupt the air-fuel mixture. Testing the Mass Airflow Sensor (MAF) is another crucial step, since a malfunctioning MAF can cause rough idling. Finally, assess the fuel system by checking the fuel filter and injectors for clogs, as these can also affect engine performance. By systematically following these diagnostic steps, you can effectively identify and address the causes of a rough idle, making your DIY troubleshooting more efficient and successful.

What are the common causes of a rough idle in a 2014 GMC Terrain?

When dealing with a rough idle in your 2014 GMC Terrain, it's crucial to understand the common problems that could be at play. One of the primary culprits is a dirty or clogged air filter, which can significantly restrict airflow to the engine, leading to performance issues. Additionally, faulty spark plugs are notorious for causing misfires, which can manifest as a rough idle. Another potential issue is vacuum leaks; these can disrupt the delicate air-fuel mixture necessary for smooth engine operation. Fuel system problems, such as clogged fuel filters or injectors, can also hinder engine performance and contribute to rough idling. Furthermore, a malfunctioning mass airflow sensor can throw off the air-fuel balance, exacerbating the issue. Lastly, don't overlook the Exhaust Gas Recirculation (EGR) valve, as its failure can disrupt the combustion process, leading to an uneven idle. By identifying and addressing these common issues, you can restore your GMC Terrain's performance and enjoy a smoother driving experience.

How urgent is it to address the rough idle in a 2014 GMC Terrain?

Addressing a rough idle in your 2014 GMC Terrain is not just a matter of comfort; it is crucial for the overall health of your vehicle. A rough idle can signal various underlying problems, such as dirty fuel injectors or a malfunctioning oxygen sensor, which, if ignored, may escalate into more severe issues. Neglecting this symptom can lead to decreased fuel efficiency and engine misfires, ultimately resulting in costly repairs. Moreover, a rough idle can indicate potential safety risks, as it may affect your vehicle's performance and reliability on the road. By prioritizing timely diagnosis and maintenance, you can prevent further damage and ensure your GMC Terrain operates smoothly, safeguarding both your investment and your safety. Therefore, it is essential to address any signs of a rough idle promptly to maintain optimal vehicle performance and longevity.

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