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2017 Silverado 1500 5.3L Rough Idle & Misfire - CEL On

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Mike T. · rep 0 · May 25, 1:39 AM · 1 replies · solved · Question

Vehicle: 2017 Chevrolet Silverado 1500 LT

Hey everyone, I'm having some trouble with my 2017 Chevrolet Silverado 1500, specifically the 5.3L V8 engine. Lately, it's developed a really rough idle, especially when I'm stopped at a light or in park. The whole truck shudders a bit.

To make things worse, the Check Engine Light came on a few days ago. I got it scanned at an auto parts store, and it's showing multiple misfire codes, specifically P0301 and P0303, indicating misfires on cylinders 1 and 3. Sometimes, it feels like it lacks power during acceleration.

I've checked the basic things like air filter, but I'm not sure where to go from here. Could it be spark plugs, ignition coils, or something more serious? Any advice for a 2017 Silverado LT owner?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 1:39 AM

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ClearTheCode admin answer:

Rough idle and misfire codes (P0301, P0303) on your 2017 Chevrolet Silverado 1500's 5.3L V8 are common issues that can stem from several sources. Addressing these promptly is crucial to prevent further engine damage.

Common Causes:

  • Ignition System: Worn spark plugs, faulty ignition coils, or bad spark plug wires (less common on newer models) are frequent culprits. Given the specific cylinder codes, it's likely isolated to those cylinders.
  • Fuel System: Clogged or failing fuel injectors for cylinders 1 and 3 can lead to an improper air/fuel mixture, causing misfires. A dirty fuel filter could also contribute, though usually to more widespread issues.
  • Vacuum Leaks: A vacuum leak near the intake manifold can cause unmetered air to enter the engine, leading to a lean condition and misfires.
  • PCV System: A malfunctioning PCV valve or hose could impact engine vacuum and cause issues.
  • AFM/DOD System: Chevrolet's Active Fuel Management (AFM) or Dynamic Fuel Management (DFM) systems on these engines can sometimes cause lifter issues, leading to misfires. This is a more serious concern.

Troubleshooting Steps:

  1. Check Spark Plugs and Coils: Visually inspect the spark plugs and ignition coils for cylinders 1 and 3. Look for signs of wear, oil fouling, or damage. You can swap coils between cylinders to see if the misfire code follows the coil.
  2. Fuel Injector Test: A professional can test the fuel injectors for proper spray pattern and flow rate. Sometimes, a fuel system cleaner can help with minor clogs.
  3. Vacuum Leak Check: Use a smoke machine or listen for hissing sounds around the intake manifold and vacuum lines.
  4. Compression Test: If basic checks don't yield results, a compression test can identify internal engine issues like a bad valve or piston ring, or an AFM lifter failure.

When to See a Shop:

It's recommended to see a professional shop if:

  • You've performed basic checks (plugs, coils) and the issue persists.
  • You suspect a fuel injector problem, as specialized tools are often needed for diagnosis.
  • There's any suspicion of a vacuum leak that you can't locate.
  • The misfire is accompanied by unusual engine noises (ticking, knocking), which could indicate AFM lifter failure or other internal damage. Driving with persistent misfires can damage the catalytic converter.
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