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2018 Sierra 1500 5.3L Misfire and Ticking - AFM/Lifter Issues?

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Mark S. · rep 0 · May 22, 3:38 AM · 1 replies · solved · Question

Vehicle: 2018 GMC Sierra 1500 SLT

Hey everyone,

I've got a 2018 GMC Sierra 1500 SLT with the 5.3L V8, and I'm running into some frustrating engine problems. Lately, I've noticed a distinct ticking noise coming from the engine, especially when it's cold, and it seems to get louder under load. The truck also feels like it's misfiring occasionally, and the check engine light has come on a few times.

I scanned it with my OBD-II reader, and I'm getting codes like P0304 (Cylinder 4 Misfire) and sometimes P0521 (Engine Oil Pressure Sensor Range/Performance). I've heard about active fuel management (AFM) or dynamic fuel management (DFM) lifter issues on these trucks, and I'm wondering if that's what I'm dealing with. The truck has about 85,000 miles on it.

Has anyone else experienced this with their 2018 Sierra or similar GMC trucks? What was your fix? I'm hoping it's not a major engine overhaul.

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 3:38 AM

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ClearTheCode admin answer:

It sounds like you're experiencing common symptoms associated with Active Fuel Management (AFM) or Dynamic Fuel Management (DFM) lifter failures in GM's V8 engines, particularly the 5.3L. The ticking noise and misfire codes (P0304) are strong indicators.

Causes:

  1. AFM/DFM Lifter Failure: The lifters designed for cylinder deactivation can fail due to oil starvation, wear, or collapse, leading to improper valve operation and misfires.
  2. Oil Pressure Issues: The P0521 code suggests a problem with the oil pressure sensor or the oil pressure itself, which can exacerbate lifter issues or be a symptom of internal engine wear.
  3. Carbon Buildup: While less likely to cause ticking, carbon buildup on valves can contribute to misfires.

Diagnostics & Next Steps:

  1. Verify Oil Pressure: Have a shop manually check your engine's oil pressure with a mechanical gauge to confirm if the P0521 is a sensor issue or an actual low oil pressure problem.
  2. Cylinder Contribution Test: A technician can perform a cylinder contribution test to pinpoint which cylinder(s) are underperforming.
  3. Valve Cover Removal: Visual inspection after removing the valve cover can often reveal collapsed or damaged lifters, especially on the affected cylinder.
  4. Borescope Inspection: A borescope can be used to inspect the camshaft lobes for wear without full engine disassembly.

When to See a Shop:

You should take your Sierra to a qualified mechanic or GMC dealership as soon as possible. Continuing to drive with a failed lifter can lead to more severe engine damage, including camshaft wear, cylinder head damage, and potentially catastrophic engine failure. Addressing it early can prevent more costly repairs down the line. Be prepared for a potential repair involving lifter and camshaft replacement, and possibly an AFM delete kit if you wish to prevent future issues.

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