Not often, hopefully.
Since I bought my truck it's had a bit more of an idle knock than I'm comfortable with and a bit of a shake at idle as well. It runs good, gets great mileage, and starts fine, but I'd like to smoothe out the idle if I can.
I've changed the FCA and it made no difference. I'm not about to replace or try to repair all the injectors because the truck runs great, but if I can nail down which injector is the culprit (if it is an injector), I'd replace it.
So being able to shut down injectors one at a time would be nice.
-john