A customer recently brought in his delivery van that was running rough and had a check engine light on. The customer also complained that they had been using more gas than normal. After our diagnosis, we found out that the spark plugs were completely worn out. The vehicle had 134,000 miles on it, and had never changed the spark plugs.
Other symptoms of bad spark plugs are hesitation, lack of power, hard starts, and rough idle. When you have incomplete combustion, these unburden gas enter your exhaust system and may damage the catalytic converter. What are you going to do? Change your spark plugs every 100,000 miles.
Also included in a tune up, we would recommend changing the fuel filter, pcv valve, performing a fuel injection service, and checking the engine filters. This is normal preventive maintenance. You can you this on a timed schedule and bypass the check engine light coming on for this issue.