Digital BW, The Print

I have converted my Epson R800 to a carbon black B&W printer using 
advice from Paul Roark and QTR and Eboni inks from MIS.

The B&W part works really well, and I am really pleased, B&W being 
most of my printing.

But I was led to believe that I could use the remaining Epson inks to 
print color "as if nothing had been changed in the R800."  I tried to 
print a quick portrait of my daughter yesterday and was really 
surprised to see how badly the printer did on color.  I am totally 
sure that this is opperator-error, not bitching at the printer, but 
what did I do wrong?  The print was really, really dark, and I am 
wondering if I somehow didn't set the "glop" position to be off.  If 
the printer thought that that cartridge space still had glop in it, 
wouldn't it lay down MIS Eboni ink "as if" it were glop?

If anyone knows the whys and hows of printing color on this printer, 
I would appreciate the advice.

Thanks.

D.