pattern is k1, *sl 1 pwise wyif, k1, repeat from *
Hmmm. If you do a yarn over you will be making a lot of increases across the row, as well as holes. Does this sound right for your pattern? There is another way to interpret that, which would be: "knit 1, *with the yarn in the front slip 1 purlwise, then move the yarn to the back going not over but between the needle tips and knit 1, repeat from the *. If you do this it will put a strand of yarn across the front of the each slipped stitch. It will not make any holes or increases. Sometimes they ask you to do something like that for the little effect of the horizontal line running across the fabric. Which option makes the best sense in your situation?