Answer: Technicians recommend that fuel injection service be performed every 30,000 miles to keep your fuel injectors working efficiently and your vehicle operating at peak-performance levels. There are also several symptoms to watch for to determine if you need fuel injection service, which include the following: lean misfire, which is a misfire caused by an air/fuel mixture that is too lean, meaning there is not enough fuel (a lean misfire will trigger your “check engine” light); rough idle; poor acceleration; and higher carbon monoxide or hydrocarbon emissions.