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Recipe - 6.6L V8 Gasoline (GM HD, L8T 2020+)

Specific Fix build

Reliability tier: aggregated - verify before ordering, see /disclosure/

Rough idle or hesitation on a high-mileage 6.6L L8T: direct injection leaves the intake valves unwashed - borescope before cleaning, and rule out ignition and injectors (same symptoms) (mode Intake-valve carbon buildup (direct injection, no port wash)).

Parts

• gm-hd-gas-l8t: intake-valve-cleaning-service (service item) - walnut-blast or chemical intake-valve cleaning (shop service) (qty 1)
• gm-hd-gas-l8t: oil-catch-can-kit (honest catalog gap) - oil catch can, community preventive (catalog gap) (qty 1)

Install order

1. rule out ignition and injector causes first (same symptoms)
2. borescope the intake valves
3. clean the valves if deposits are confirmed
4. optional: fit an oil catch can or separator as a preventive

Expected outcome

Idle quality restored where deposits were the cause.

DIY or shop: Shop job