Home › Forums › Stay Dirty Lounge › Service and Repair Questions Answered Here › LS1 Gen 3 Pre Ignition › Reply To: LS1 Gen 3 Pre Ignition March 17, 2021 at 6:06 am #989467 Richard KirshyParticipant Common causes: Glowing hot or melted spark plugs Glowing hot exhaust valve Burning carbon embers Generally the fix(s) for pre ignition : Run higher octane fuel. Run the engine on the rich side. Try playing with ignition timing.