2008 Chevrolet Suburban Cylinder 6 Misfire: Engine and Traction Lights On After Spark Plug Replacement
I recently purchased a 2008 Chevrolet Suburban five weeks ago. Three days ago, while driving, the engine light and traction control light came on simultaneously. I took it to a friend for a diagnostic scan, which revealed a misfire in cylinder 6. We replaced the coil pack for cylinder 6, as well as all spark plugs and plug wires. After the replacement, we returned the vehicle, but the misfire persists—now accompanied by severe engine shaking. The truck was purchased for $17,000 cash with no warranty, sold 'as-is,' yet it ran smoothly at the time of purchase. I've already tried adding Sea Foam to the fuel with no improvement. Both the engine and traction lights remain on. What could be causing this issue? Is there a deeper underlying problem related to active fuel management (AFM) or another component?
If your vehicle has Active Fuel Management (AFM), it's important to check for known AFM-related issues in the 2008 Chevrolet Suburban. A cylinder misfire with persistent shaking could be linked to AFM system faults. Confirm whether the engine is running on AFM mode—this may affect how misfires are detected and reported. Regarding the traction control light: this often correlates with ABS fault codes. Is the ABS warning light illuminated? Does it come on during startup or under specific conditions? If no code was displayed for the traction issue, verify that your scan tool is capable of reading ABS-related diagnostic trouble codes—many basic OBD2 scanners cannot detect these. Additionally, to confirm spark presence at cylinder 6: when you remove the spark plug, check its condition. Is it wet, dry, black, or tan? A dry spark plug suggests a misfire issue beyond just ignition components—this may point toward compression problems. Lastly, ensure that the spark plugs used are AC Delco (original equipment) to maintain compatibility with the 2008 Suburban's engine system.