[RayR]

Probably not a good idea, Fava isn't a low growing vetch, they get anywhere from 2.5Ft to over 3Ft. tall with broad leaves and side branches coming from the soil line. By the time you planted your tomatoes, the Fava would have already reached a appreciable size and would shade out the young Tomato plants. I plant Fava in very early April, so by the time late May rolls around to plant the tomato seedlings, the Fava is already quite tall and still growing.
I usually grow radishes as a companion crop in between the rows of Fava plants since Radish grows faster and is harvested before the Fava is tall enough to shade out the Radishes. At least that's the plan, it doesn't always work out that way. If you get a mild spring, not too cold and not too wet, those Fava plants can grow quite fast and tall. In 2010, which had a spring like that, I had Fava plants so tall I had to stake them to keep them from falling over from the wind and the weight of the pods.

I added a picture from June 17, 2010 so you can see what I mean