Yes thats correct for the big jump in timing. Your going from the idle timing table to the regular timing table.
I've never ran into this problem with both my cars. Timing at idle via datascan is always stable (not in base timing mode)
Now with my experience checking timing at the distributor with a timing light has always been stable but always shows 5 deg lower timing when not in timing mode. When put into timing mode it jumps 5 degs showing the correct base timing.
lol wierd.. just my thoughts
I've never ran into this problem with both my cars. Timing at idle via datascan is always stable (not in base timing mode)
Now with my experience checking timing at the distributor with a timing light has always been stable but always shows 5 deg lower timing when not in timing mode. When put into timing mode it jumps 5 degs showing the correct base timing.
lol wierd.. just my thoughts