The 2019 Chevrolet Suburban's 5.3L and 6.2L V8 engines use Active Fuel Management (AFM) to improve fuel economy by deactivating cylinders. Unfortunately, the specialized AFM lifters can fail, causing engine noise, misfires, and potential damage. Understanding this issue helps owners make informed repair decisions.
How AFM Works and Why It Fails
AFM lifters have internal mechanisms that can lock out under oil pressure control, preventing the valves from opening on deactivated cylinders. This complexity creates more potential failure points compared to standard hydraulic lifters.
Common failure modes include the lifter collapsing (losing height), the locking mechanism sticking or failing, and internal component wear. When a lifter fails, it affects valve actuation on that cylinder, causing misfires and the characteristic ticking noise.
Recognizing AFM Lifter Failure
The primary symptom is a pronounced ticking or tapping noise that follows engine RPM. This tick is often louder than normal valve train noise and may be isolated to one side of the engine. The noise is often most noticeable at idle and light throttle.
Accompanying symptoms include cylinder-specific misfire codes (P0300-P0308), rough running, reduced power, and potential oil consumption if the lifter has damaged the camshaft lobe.
Diagnostic Confirmation
Professional diagnosis involves using a mechanic's stethoscope to pinpoint the noise location and scan tools to identify which cylinder is misfiring. In some cases, valve cover removal allows visual inspection of lifter condition.
If the lifter has been collapsed for a while, the camshaft lobe may show wear. Inspecting the cam is important during repair to determine if it needs replacement along with the lifters.
Repair Options
Standard repair replaces the failed lifter(s). However, most shops recommend replacing all lifters on the affected bank or all 16 lifters to prevent future failures. Parts include lifters, lifter guides, and gaskets for reassembly. Labor is significant due to required disassembly.
AFM delete replaces all AFM lifters with standard lifters and uses a performance tune to disable cylinder deactivation. This eliminates the failure-prone components permanently but requires a tune that may affect warranty and slightly reduces fuel economy.
GM Special Coverage
GM has acknowledged AFM lifter issues through technical service bulletins and special coverage programs. Check with your dealer about applicable coverage for your 2019 Suburban's VIN. Many owners have received repair assistance through these programs.