Cylinder 6 Misfire Detected

Cylinder 6 is an AFM cylinder on the GM 5.3L V8. A collapsed AFM lifter is the most common cause of persistent cylinder 6 misfire. GM TSB #18-NA-355. Check lifter preload with the valve cover removed. If collapsed, replace all 16 lifters. Consider an AFM delete kit to prevent recurrence. Also check the VLOM solenoid for cylinder 6.

Cylinder 6 misfire on the Pentastar V6. Swap the ignition coil to another cylinder to test. If the coil is good, check for a failed rocker arm -- the Pentastar has a known issue with rocker arm needle bearings failing. TSB 09-002-14. If you hear a ticking noise, inspect the rocker arms on cylinder 6. Replace all rocker arms in the affected head.

Cylinder 6 misfire on EcoBoost. Perform a coil swap test (Motorcraft DG-549). Cylinder 6 is on the passenger side rear -- harder to access. If coil and plug are good, check for carbon buildup on the intake valve using a borescope. Direct injection engines build up carbon since fuel does not wash the valve. Walnut blast cleaning resolves the issue.

Cylinder 6 on the VQ35DE is the rear bank passenger side. Swap the ignition coil to verify. If the coil is good, check fuel injector operation with a noid light. VQ35DE engines can develop individual cylinder compression loss from worn valve seals at high mileage. Perform a compression and leak-down test to rule out internal issues.