Ip8750 black and white prints a bit muddy

[Guy24]

Hi. Hope all had a good Christmas. I purchased a canon ip8750 printer and have been very impressed with the colour prints. I use fotospeed paper with custom icc profiles and a calibrated screen. However when I print black and white the prints are not black and white - they look slightly muddy/sepia. I understand printers can struggle with black and white.

Has as anyone else experienced this problem and have any suggestions?

thanks

Guy