The largest online repair guide library for every car

About us
Contact support
FAQ
Sign up
Sign in

2017 Mirage Rough Idle and Misfires

0

Ryan M. · rep 0 · May 22, 5:31 AM · 1 replies · solved · Question

Vehicle: 2017 Mitsubishi Mirage ES

Hi everyone,

I own a 2017 Mitsubishi Mirage ES with the 1.2L 3-cylinder engine, and it's been giving me some trouble lately. For the past few weeks, the car has developed a really rough idle, especially when it's cold or after driving for a bit and then stopping at a light. The engine shakes quite a bit, and it feels like it's about to stall.

Occasionally, I also get a check engine light flashing, which usually indicates a misfire. The light goes away after a while, but the rough idle persists. I've tried putting in premium fuel just in case, but it hasn't made any difference. The car has about 60,000 miles on it. What could be causing this? Is this a common problem for the Mirage?

Any advice on what to look for or what might be the culprit would be really helpful. Thanks!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 5:31 AM

0

ClearTheCode admin answer:

Rough idle and intermittent misfires, especially with a flashing check engine light, are clear indicators of an engine combustion issue in your 2017 Mitsubishi Mirage. The 1.2L 3-cylinder engine, while generally reliable, can develop these symptoms due to several common factors.

Common Causes:

  1. Spark Plugs: Worn or fouled spark plugs are a very common cause of misfires and rough idle. They should be replaced according to the manufacturer's schedule.
  2. Ignition Coils: A failing ignition coil (one for each cylinder in a 3-cylinder engine) can lead to intermittent misfires on a specific cylinder.
  3. Fuel Injectors: Clogged or faulty fuel injectors can disrupt the air-fuel mixture, causing misfires and rough idling.
  4. Vacuum Leaks: Leaks in the intake manifold or vacuum lines can introduce unmetered air into the engine, leading to an incorrect air-fuel ratio and rough idle.
  5. PCV Valve: A clogged or faulty PCV (Positive Crankcase Ventilation) valve can affect engine vacuum and cause rough idling.
  6. Oxygen Sensors: Faulty O2 sensors can send incorrect data to the engine control unit (ECU), leading to an improperly balanced air-fuel mixture.

Troubleshooting Steps & When to See a Shop:

  1. Read OBD-II Codes: The flashing check engine light indicates active misfires. Use an OBD-II scanner to read the codes. You'll likely find P030X codes (e.g., P0301 for Cylinder 1 Misfire, P0302 for Cylinder 2, P0303 for Cylinder 3) which will pinpoint the affected cylinder(s).
  2. Inspect Spark Plugs and Coils: Once you know the misfiring cylinder, visually inspect the spark plug and ignition coil for that cylinder. Look for signs of wear, carbon buildup, or damage.
  3. Fuel System Check: A shop can perform fuel pressure tests and check injector spray patterns to rule out fuel delivery issues.
  4. Vacuum Leak Test: A smoke test can effectively identify any vacuum leaks in the intake system.

Recommendation: Since the check engine light is flashing, indicating active misfires that can damage the catalytic converter, it's crucial to address this promptly. Get the OBD-II codes read immediately. Based on the codes, you can start with inspecting/replacing spark plugs and ignition coils. If the problem persists, a professional diagnosis is essential to prevent further engine damage.

Menu

Help & account