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2020 Mirage G4 SE - Rough Idle & Stalling at Stops, No CEL Yet

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Ashley M. · rep 0 · May 22, 5:29 AM · 1 replies · solved · Question

Vehicle: 2020 Mitsubishi Mirage G4 SE

Hi all,

I'm having some issues with my 2020 Mitsubishi Mirage G4 SE. Lately, it's developed a really rough idle, especially when I'm stopped at a light or in traffic. It feels like it's about to stall, and sometimes it actually does, which is pretty unnerving.

Oddly enough, there's no Check Engine Light on yet, which makes it harder to diagnose. The car has about 45,000 miles on it. I've checked the basic fluid levels, and they seem fine.

Could this be spark plugs, or something more serious? Any ideas on what I should be looking at first? It's making my daily commute a bit stressful.

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 5:29 AM

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ClearTheCode admin answer:

A rough idle and stalling on your 2020 Mitsubishi Mirage G4 SE, even without a Check Engine Light, can be caused by several common issues. The lack of a CEL often means the problem isn't severe enough to trigger an emissions-related fault, but it still warrants attention.

Here are some potential causes and diagnostic steps:

  1. Spark Plugs/Ignition Coils: Worn spark plugs or failing ignition coils are a very common cause of rough idle and misfires. Given your mileage, it's a good time to inspect or replace the spark plugs if they haven't been done recently.
  2. Mass Air Flow (MAF) Sensor: A dirty or failing MAF sensor can send incorrect air intake readings to the engine control unit (ECU), leading to an improper air/fuel mixture and a rough idle. You can try cleaning it with a specialized MAF sensor cleaner.
  3. Vacuum Leaks: Leaks in vacuum lines or intake manifold gaskets can introduce unmetered air into the engine, causing an erratic idle. Listen for hissing sounds under the hood and visually inspect all vacuum hoses.
  4. Throttle Body: A dirty throttle body can restrict airflow at idle, leading to stalling. Cleaning the throttle body can often resolve this.
  5. Fuel System Issues: A clogged fuel filter or weak fuel pump could lead to insufficient fuel delivery, especially at idle. While less common without a CEL, it's a possibility.
  6. Idle Air Control (IAC) Valve (if equipped): If your Mirage G4 has an IAC valve, it could be sticking or dirty, preventing proper idle speed regulation.

What to do next:

  • Scan for Pending Codes: Even without a CEL, there might be 'pending' codes stored in the ECU. A more advanced scanner can retrieve these.
  • Inspect Spark Plugs: Remove and inspect your spark plugs for wear, fouling, or incorrect gap.
  • Clean MAF Sensor and Throttle Body: These are relatively easy DIY tasks that can often resolve idle issues.

When to see a shop:

If cleaning the MAF sensor and throttle body, and checking/replacing spark plugs doesn't resolve the issue, or if you're uncomfortable performing these steps, it's best to take your vehicle to a professional. A mechanic can perform a more thorough diagnosis, including checking fuel pressure, vacuum levels, and performing a smoke test for vacuum leaks, to accurately identify the root cause of the rough idle and stalling.

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