Foundation Wall Repair Problem
It's hard to imagine what would have caused the
damage, if we look closely there's a large piece of concrete pulling
away from the foundation wall and there's also a large section of stucco
or plaster that seems to be falling off of the stucco foundation wall.
On the far left side of the picture, the foundation still looks like the stucco or plaster is flaking off in small and large areas.
There is a very good chance that this foundation problem was caused from water or moisture, but if you look closely, the stucco on the right side of the picture, above the lower damage, looks like it's in good shape. If you look closely, the stucco on the right side of the picture has a nice stucco texture, where the stucco on the left side of the picture underneath the porch doesn't.
Here's what I think the problem is, someone re-color-coated or textured, underneath the porch area and they either didn't prepare the existing surface properly, before applying the new texture, or they used the wrong product.
Now what about the foundation wall damage in the right bottom corner, of the picture. It looks like someone blocked a crawlspace vent, using a concrete block wall cap. They didn't attach it properly and over time, as moisture worked its way behind the block wall cap, it started to separate from the building foundation wall.
Home Repair Tip: The first thing you're going to want to do, is to remove the block wall cap, that is covering the foundation vent. Then you will need to scrape away all of the loose stucco, make sure that the concrete foundation wall is exposed, (there shouldn't be any loose stucco left on the wall) and then re-apply your new texture.
Make sure that there aren't any sprinklers, or water that's spraying onto the concrete foundation wall. I believe that moisture, is the cause of this foundation repair problem and you need to stop the moisture, in order to solve your problem.