GM 5.3L V8
5.3L AFM/DFM cylinder deactivation diagnosis
Diagnosing Active and Dynamic Fuel Management faults on the 5.3L.
Why this matters on the GM 5.3L V8
2014–2018 5.3L engines use Active Fuel Management (cylinders 1, 4, 6, 7); 2019+ engines use Dynamic Fuel Management that can shut off any cylinder. Deactivation lifters and the oil-control valve assembly are known failure points.
Symptoms owners notice
- Misfire codes on deactivating cylinders
- Tick at idle
- Rough running in V4/deactivation mode
What we check
- Misfire counters by cylinder
- Oil pressure and VLOM/oil manifold inspection
- Valvetrain inspection
Repair work involved
- Lifter, oil manifold and related valvetrain repair to factory configuration