Disney embroidary pe18od loose stitches under work what am i doing wrong

Not sure what you mean by "tacking" stitch. Are the stitches exceedingly long like a basting stitch? That would need a stitch length adjustment so stitches are closer together.

Or, do you mean the tension is loose between stitches? You can try tightening the top tension to see if that helps. (Be sure to ALWAYS RAISE the presser foot when threading the top thread so the thread will seat completely in the tension disk or you may end up with lots of top thread showing under the fabric.) If the bobbin thread is too loose, you may need to adjust its tension.

Understanding Thread Tension Threads

Check your stitch sample. The loose stitches under the fabric--are they actually top thread???? Usually,stitch problems under the fabric is a result of a top thread problem. In this case, it could be bird nesting.

Remove the top thread from the machine.
Install a brand new needle.
ALWAYS RAISE the presser foot.
Rethread from the beginning.

Sewing Machine Thread Bunching Up Here Why

Birds nest under the fabric big loops of thread top side looks good...

try changing the needle
rethread the machine top and bobbin
make sure the bobbin is inserted correctly into the bobbin case
and that the bobbin is turned the right way
make sure the thread has not come off the thread take up lever
if the machine continues to see bunch thread underneath then the
machine may need to be checked to see if some part has become
damaged or out of alignment

here's a link for parts & it shows a bobbin

http://www.sewingpartsonline.com/brother-pe180d-parts.aspx

have you tried changing the needle?
clean under the needle plate & in the bobbin area for lint or loose threads
also check the top tension

check the feed dogs under the needle plate to see if there up or down
if there down then the feed dog switch need to be moved to the up position
but if there up,,,then the machine needs to be serviced so the feed dogs & stitches can be checked

Ive started using pre wound bobbins machine is working perfectly now though had the same problem as you at first

i also have this problem if anyone can help with setting the timing on this machine

make sure needle is in the highest position before you thread
mary h

My 270D does this when I'm about to run out of bobbin. If you just replaced it I'd guess you either wound it wrong or are using the wrong type of bobbin spool. It could be too loosely or too tightly wound.