Just found today when I hold the rpm between about 1700 - 2000 in park the engine has a slight misfire, not consistent but every few cycles, also there is some smoke that smells like when they are running cold. Can not notice it at low rpm or at a higher rpm? It leads me to believe it could be a bad injector but how can you test them.

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2014 Chevy Silverado Crew Cab 5.3 Ecotec LTZ Z71 4x4
2012 Ford F-150 XLT EcoBoost 4x4
2007 Chevy Silverado 2500 HD D-Max 4x4
1996 Dodge Ram 1500 4x4 (just about dead)
2006 Jeep Liberty CRD

A injector return flow test is the easiest to perform.

Any codes?

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U.S. Army Retired

mine does it to , when i got it (all stock ) and after with 2 new injectors and 2 old tested good, GDE tune and new rockers , i don't know why ? but mine drives and runs like new so no smoke, but it does it about 1800rpm in park only. you can do test like return flow but it won't tell you much . only accurate test is BOSCH bench test,