Here's something interesting (to me) that just happened to me on the 1604. I have been having issues with the black coming through the head for some time now. After a while, now the cyan doesn't send the lighter droplets sharp enough to land on the media leaving overspray when used.
So today, after reading this thread, I decided to run a print on 1440x720 variable (usually rund 720x720v). The test print I use are swatches of all colors including a rich black, green, red and blue. This time the test ran beautifully giving me a deep red I loved. I was so excited about seeing my true black again. Sure it's slower but it's BLACK!
Then I decided to run a test with less ink limit (from 300 I dropped to 250) and I'm back to where I started. No black coming out of the head again.
How can it be that suddenly all that ink came through and then not? Any ideas as to what can cause it to work that way?
jc
PS. Don't mean to be a thread pirate, just thought it was related to the topic. I can move it to a new thread if needed.