Mitsubishi Lancer Has Rough Idle

Common Causes of Rough Idling in Your Mitsubishi Lancer and How to Resolve Them

Find Repair Location
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 Mitsubishi Lancer 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 Mitsubishi Lancer 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.

Customers with drum brake systems often specify they have lost braking power, or that the vehicle's brakes are making noise. This is because brake drums do not dissipate heat very well, so the heat from hard braking will cause stress fractures. These fractures make can make noise on the brake shoes as the drum revolves around the shoes. Lastly, the brake shoes may not be problematic, but may cause a grinding noise while stopping. This would indicate the shoes have no braking material left, and the brake shoes must be changed before the vehicle can be safely driven.

Learn more about brake shoe symptoms

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.

Troubleshooting Rough Idle in a Mitsubishi Lancer

When troubleshooting a rough idle in your Mitsubishi Lancer, it's crucial to follow a structured diagnostic approach that prioritizes simpler fixes before delving into more complex issues. Begin by checking for vacuum leaks, as they are a frequent cause of idle problems. Inspect all vacuum hoses and connections for any signs of damage or disconnection that could disrupt the engine's airflow. After addressing potential leaks, examine the spark plugs; worn or fouled plugs can lead to misfires, significantly affecting idle quality. If the spark plugs are in good condition, the next step is to evaluate the ignition coil, which is essential for generating the spark that ignites the air-fuel mixture. A faulty ignition coil can lead to misfires and contribute to a rough idle. If these preliminary checks do not resolve the issue, further diagnostics may be necessary to uncover deeper problems, such as ignition misfires indicated by specific error codes. By methodically addressing these areas, you can effectively identify and rectify the cause of the rough idle in your Mitsubishi Lancer.

Troubleshooting Rough Idle Issues in a Mitsubishi Lancer

When troubleshooting rough idle issues in a Mitsubishi Lancer, it's essential to identify the common problems that may be affecting your vehicle's performance. A vacuum leak is often a primary suspect, as it can disrupt the air-fuel mixture, leading to poor engine operation and decreased fuel efficiency. Additionally, worn or faulty spark plugs can cause misfires, resulting in an uneven idle that can be frustrating to experience. It's also vital to check the ignition coil, as a failing coil can trigger warning lights and significantly impact engine performance. Engine misfires, which may be accompanied by a noticeable loss of power, can indicate more serious underlying issues that need to be addressed promptly. If you notice that your Lancer shakes at idle but runs smoothly when accelerating, the problem could lie with the motor mounts, which may not be effectively absorbing engine vibrations. To prevent these issues from occurring, regular maintenance is key; this includes routine checks of spark plugs and the ignition system. By accurately diagnosing the specific cause of a rough idle, you can take the necessary steps to implement effective solutions and restore your Mitsubishi Lancer's smooth operation.

Why is a Rough Idle in a Mitsubishi Lancer a Cause for Urgent Attention?

A rough idle in your Mitsubishi Lancer is not just an annoyance; it signals potential engine problems that require immediate attention. Ignoring this symptom can lead to misfires, which disrupt the engine's performance and result in inefficient combustion, ultimately affecting fuel economy and power. Common culprits like vacuum leaks, faulty spark plugs, or ignition coil issues can exacerbate the situation, leading to more severe engine damage if left unresolved. Additionally, a rough idle may indicate a malfunctioning fuel injection system, which can cause improper air-fuel mixtures and further compromise engine performance. If you notice your engine shaking at idle but smoothing out during acceleration, it’s crucial to investigate the cause, as this could lead to stalling or erratic idle speeds that pose safety risks. By addressing a rough idle promptly, you not only enhance your vehicle's performance but also prevent costly repairs down the line, ensuring a safer driving experience.

You’ve got options with RepairPal

Whether you need a more accurate auto repair estimate or help finding a reputable shop in your area, we’ve got you covered.