- Found P0300 – multiple cylinder misfire detected. Monitored engine live data while running and found misfires on all cylinders, however cylinder 8 was severely misfiring. Removed spark plugs from engine and found NGK TR5 spark plugs had been installed. While these spark plugs do fit the engine, they are the incorrect style and may result in poor performance/misfires. Cylinder 8 spark plug was older and a different style NGK plug. Spark plug on cylinder 8 was severely contaminated with oil and extremely worn out. It appears because of the difficulty to access cylinder 8 plug, some one had left it in the engine and changed the other 7 plugs. Noticed oil on all spark plugs after removing. Inspected cylinders/pistons with borescope and found abnormal wear/damage to tops of pistons on cylinders 6 and 8. Customer stated the engine was consuming oil at a high rate. Suspect oil consumption from piston rings. Checked engine oil and found it low by 1 quart. Topped off engine oil. Customer made aware of spark plug mismatch and damage to tops of pistons. Replaced spark plugs with OEM ACDelco Iridium plugs. Replaced battery. Following repairs, monitored engine data and found no misfires on any cylinders.
Jack C. gave our service a 5 star review on 11/17/2022