How to isolate a bad/leaky injector ??

[Katmandu]

My 81 has a "miss" in the engine most noticeable right above idle. It also has greyish smoke coming out the exhaust.

 I think it's caused by a leaky/bad injector.  ??

 How does one isolate a leaky/bad injector ??

[hillfolk'r]

fire it up,,and make it miss,,,thengrab a 17mm wrench,and start loossening (sorry,spelling,im tired)the injector lines,,while the engine is running,,,,if that injector is working good,then you will hear the revs drop,this is a good injector,,,after checking each one,tighten the line back up,,,,if you break one loose(line),and the revs dont drop,thats the baddie!!!EASY!! and good to know,,its the same as pulling spark plug wires off a gasser,to check cyls,,,good luck,,next time ill tell ya how to "spill  time" your engine's injector pump,if needed!!!actually i gotta check some dudes mercedes timing,igotta spill time that

[fspGTD]

moved to troubleshooting.

[745 turbogreasel]

It may help to raise engine speed a bit above idle (steady throttle) so the idle speed circuit doesn't try to fool ya.