@carls_garage: 🔧 TOW-IN OF THE DAY! TWO DEAD CYLINDERS! 😳 This 2008 Chevy Silverado 1500 5.3L V8 was towed into Carl’s Garage with a severe misfire, rough idle, and an engine that sounds terrible! Using my TOPDON ArtiDiag800 BT, live misfire data showed cylinders 3 and 4 misfiring constantly while the other six looked good. The owners suspected the dreaded AFM lifters. But here’s the twist: GM’s Active Fuel Management uses special lifters on cylinders 1, 4, 6 and 7. Cylinder 4 is AFM; cylinder 3 has conventional lifters! 🔍 WHAT WE FOUND: ✅ Spark confirmed with an inline tester. ✅ Cylinder 3 injector was already unplugged. ✅ Spark plugs showed contamination and possible thread damage. ✅ Cylinder 3’s compression gauge barely responded (0–5 PSI), versus about 130 PSI on cylinder 1 during testing. ⚠️ Damaged spark plug threads could affect the tester seal. Internal damage isn’t confirmed yet! Low compression can cause a severe misfire even when spark and fuel delivery are fine. Possible causes include lifter or camshaft damage, a broken valve spring, a valve not sealing, piston damage, or a head gasket problem. NEXT: Verify with a proper cranking compression test, perform a leak-down test, and inspect the valvetrain under the valve covers. 🚘 Related GM V8 diagnostics: 2007–2013 Silverado/Sierra 1500, 2007–2014 Tahoe/Suburban/Yukon/Escalade, and 2007–2013 Avalanche. Relevant 4.8L, 5.3L, 6.0L and 6.2L engines vary by model; not all have AFM. At 210,000 miles, with rust and other repairs needed, would YOU rebuild it, install a used engine, or sell it? 👇 🛠️ @Topdonshop @TOPDON USA #ChevySilverado #AFMLifters #MisfireDiagnosis #EngineDiagnostics #CarlsGarage

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Wednesday 11 November 2026 22:30:25 GMT