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2016 S60 T5 - Rough Idle and Stalling at Stops

0

Mike T. · rep 0 · May 25, 3:52 AM · 1 replies · solved · Question

Vehicle: 2016 Volvo S60 T5 Momentum

Hey everyone,

My 2016 Volvo S60 T5 Momentum has developed a really annoying issue lately. When I come to a stop, especially after driving for a bit, the engine idles very roughly. It feels like it's about to stall, and sometimes it actually does, which is pretty concerning in traffic.

There's no check engine light on yet, which makes it harder to diagnose. I've tried cleaning the MAF sensor with a specific cleaner, but it hasn't made a difference. The car has about 85,000 miles on it, and I've kept up with regular maintenance.

Has anyone experienced something similar with their S60 T5? What should I be looking at next? Could it be spark plugs, or something more serious?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 3:52 AM

0

Hi Mark,

Rough idling and stalling at stops on your 2016 Volvo S60 T5 Momentum, especially without a Check Engine Light (CEL), can be frustrating to diagnose. While your MAF sensor cleaning was a good first step, there are several other common culprits for these symptoms.

Here's a breakdown of potential causes and what to check:

  1. Vacuum Leaks: This is a very common cause of rough idle. A leak in a vacuum hose or intake manifold gasket can introduce unmetered air into the engine, disrupting the air-fuel mixture. Listen for a hissing sound under the hood, or try spraying a small amount of unlit propane or carb cleaner around vacuum lines and the intake manifold (be cautious and have a fire extinguisher handy) – if the idle changes, you've found a leak.
  2. Spark Plugs/Ignition Coils: Worn spark plugs or failing ignition coils can lead to misfires, especially at lower RPMs, causing a rough idle. Even without a CEL, the misfires might not be severe enough to trigger a code immediately. Check your service records to see when the spark plugs were last replaced.
  3. Fuel System Issues:
    • Clogged Fuel Filter: A partially clogged fuel filter can restrict fuel flow, leading to lean conditions and rough running, particularly under load or at idle.
    • Weak Fuel Pump: A failing fuel pump might not be providing consistent fuel pressure, causing the engine to starve for fuel.
    • Dirty Fuel Injectors: Clogged injectors can lead to an uneven spray pattern, causing some cylinders to run lean.
  4. Idle Air Control (IAC) Valve (if applicable): Some vehicles use an IAC valve to regulate idle speed. If it's dirty or failing, it can cause erratic idling. (Note: Many modern Volvos use electronic throttle bodies for idle control, so an IAC valve might not be present).
  5. PCV System: A faulty PCV (Positive Crankcase Ventilation) valve or system can cause vacuum leaks or affect engine breathing, leading to idle issues.

What to do:

  • Check for Pending Codes: Even without a CEL, your OBD-II scanner might show 'pending' codes that haven't fully matured. This can provide a clue.
  • Inspect Spark Plugs: Remove and inspect your spark plugs. Look for signs of wear, fouling, or unusual deposits.
  • Visual Inspection: Carefully inspect all vacuum lines, intake hoses, and the PCV system for cracks, disconnections, or damage.

When to see a shop:

If the basic checks don't reveal the issue, or if you're not comfortable performing these inspections, it's time to visit a professional mechanic. A shop can perform a smoke test for vacuum leaks, check fuel pressure, and use advanced diagnostic tools to pinpoint the exact cause, even without a CEL.

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