The largest online repair guide library for every car

About us
Contact support
FAQ
Sign up
Sign in

Rough Idle and Misfire on 2017 Buick LaCrosse 3.6L - Flashing CEL

0

Angela R. · rep 0 · May 22, 3:49 AM · 1 replies · solved · Question

Vehicle: 2017 Buick LaCrosse Premium

Hello Buick owners,

I'm having a serious issue with my 2017 Buick LaCrosse Premium, equipped with the 3.6L V6 engine. Recently, it started idling very roughly, almost like it's going to stall. The whole car shakes when I'm stopped at a light. On top of that, the Check Engine Light has been flashing intermittently, especially when I accelerate or when the rough idle is at its worst.

I haven't had a chance to get the codes pulled yet, but the flashing CEL usually means a severe misfire, right? I'm worried about potential catalytic converter damage. Has anyone experienced similar symptoms with their 2017-2019 LaCrosse V6? What was the culprit? Spark plugs, ignition coils, or something worse?

Any advice on what to look for or common issues with this engine would be greatly appreciated. Thanks!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 3:49 AM

0

ClearTheCode admin answer:

A flashing Check Engine Light (CEL) on your 2017 Buick LaCrosse 3.6L, accompanied by a rough idle and shaking, is indeed a strong indication of a severe engine misfire. A flashing CEL specifically warns that a misfire is occurring that could damage the catalytic converter due to unburnt fuel entering the exhaust system.

Common Causes for Misfires (and likely DTCs like P0301-P0306):

  1. Ignition System Issues:
    • Worn or Fouled Spark Plugs: Over time, spark plugs degrade, leading to weak or inconsistent spark.
    • Faulty Ignition Coils: A failing ignition coil for a specific cylinder will prevent proper spark generation.
  2. Fuel System Issues:
    • Clogged Fuel Injector: An injector that's not delivering enough fuel to a cylinder will cause a lean misfire.
    • Low Fuel Pressure: A failing fuel pump or clogged fuel filter can lead to insufficient fuel delivery to all cylinders.
  3. Air/Vacuum Leaks: Leaks in the intake manifold gasket or vacuum lines can introduce unmetered air, causing a lean condition and misfires.
  4. Engine Mechanical Issues: (Less common but possible)
    • Low Compression: Worn piston rings, valves, or a head gasket leak can reduce compression in a cylinder, leading to misfires.
    • Timing Issues: A stretched timing chain or faulty VVT (Variable Valve Timing) components can throw off engine timing.

When to See a Shop:

  1. Immediate Action: Do not ignore a flashing CEL. Continued driving can lead to expensive catalytic converter damage, which is far more costly than addressing the misfire source.
  2. Get Codes Pulled: The first step is to get the Diagnostic Trouble Codes (DTCs) read. Misfire codes (P030X, where X is the cylinder number) will pinpoint the affected cylinder(s).
  3. Professional Diagnosis: A qualified technician will:
    • Read all stored and pending DTCs.
    • Perform a visual inspection of spark plugs, ignition coils, and wiring.
    • Test fuel pressure and injector operation.
    • Check for vacuum leaks.
    • Potentially perform a compression test or leak-down test if mechanical issues are suspected.

Addressing the misfire promptly will prevent further damage and restore your engine's smooth operation.

Menu

Help & account