By using a multimeter across an injector, you are only determining that it is getting the open/close signals via the harness. It will not tell you if there is some mechanical issue with the injector (eg it's "dribbling"), or over/under flowing.

As you've already listened to each of them with a stethoscope, the chances are better than average that they are actually opening and closing. Whether they are flowing and sealing correctly is another matter entirely.

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Cheers,

Anthony