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2017 Mirage G4 rough idle and occasional stalling

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Jason D. · rep 0 · May 22, 5:33 AM · 1 replies · solved · Question

Vehicle: 2017 Mitsubishi Mirage G4 ES

Hey everyone,

I'm having some issues with my 2017 Mitsubishi Mirage G4 ES. It's got the 1.2L 3-cylinder engine and about 60,000 miles. Lately, the car has developed a really rough idle, especially when I'm stopped at a light or in traffic. The whole car shakes a bit, and the RPMs seem to fluctuate slightly.

Even more concerning, it's stalled on me a couple of times when coming to a stop or just after starting up. It usually restarts fine, but it's pretty unnerving. There's no Check Engine Light on right now, but I'm worried it might come on soon.

I've checked the basic things like the air filter, and it looks okay. Any ideas what could be causing this rough idle and stalling in a Mirage G4? Thanks for any help!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 5:33 AM

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ClearTheCode admin answer:

Rough idle and occasional stalling on a 2017 Mitsubishi Mirage G4, even without a Check Engine Light, can point to several common engine management or fuel system issues. The 1.2L 3-cylinder engine is known for its simplicity, but these symptoms indicate something is disrupting its smooth operation.

Here are potential causes and steps to consider:

  1. Dirty Throttle Body:

    • Cause: Carbon buildup on the throttle plate and inside the throttle body can restrict proper airflow at idle, leading to an unstable idle and stalling.
    • Action: A thorough cleaning of the throttle body with specialized throttle body cleaner can often resolve this. It's a relatively simple DIY task, but ensure you don't damage any electronic components.

  2. Faulty Spark Plugs or Ignition Coils:

    • Cause: Worn spark plugs or failing ignition coils can cause misfires, leading to a rough idle and potential stalling. Even if the misfire isn't severe enough to trigger a CEL immediately, it can still affect performance.
    • Action: Check the condition of your spark plugs. If they're old or fouled, replace them. Inspect ignition coils for any signs of cracking or damage.

  3. Vacuum Leaks:

    • Cause: A leak in any vacuum hose or gasket can introduce unmetered air into the engine, disrupting the air-fuel mixture and causing a rough idle.
    • Action: Listen for hissing sounds around the engine bay. A professional smoke test can quickly identify vacuum leaks.

  4. Idle Air Control (IAC) Valve (if equipped) or MAF Sensor:

    • Cause: If your Mirage G4 has an IAC valve, it could be dirty or failing. Alternatively, a dirty Mass Air Flow (MAF) sensor can send incorrect air readings to the ECU.
    • Action: Clean the MAF sensor with MAF cleaner. If an IAC valve is present, it might need cleaning or replacement.

When to see a shop: If cleaning the throttle body and checking spark plugs doesn't resolve the issue, or if a CEL eventually illuminates (common codes for misfires include P0300-P0303), it's time to visit a mechanic. They can perform a diagnostic scan, check fuel pressure, and conduct a more in-depth inspection to pinpoint the exact cause of the rough idle and stalling.

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