That is actually a very good result for a first large print in ABS with a printer that isn’t in an enclosure. ABS plastic will tend to split, especially in long thin runs like the location your part is splitting at. You can combat that several ways. To start with, if at all possible, increase the wall thickness. Even an additional half a mm will give you better results. Next, increase the nozzle temperature. Usually you will want to bump your base starting temperature for ABS up to 240 with the new hotend. The old hotend wasn’t able to get much past 235 safely, so it was temperature restricted. ABS will bond much better at 240. After that, if you have room on the bed, you can print with a Skirt layer. adjust the slicer settings so it generates a 1 loop thick skirt (and preferably a matching 5mm brim layer most of the way up the part. That will create a sacrificial wall around the part that will act as a thermal barrier and wind break from the bed motion. It does waste plastic, but it is effective. You can also build a temporary enclosure around your Taz using several turkey roasting bags and some tape. Make sure to leave the control box outside the enclosure (The LCD doesn’t matter, just the main box) . The ultimate fix is to either build an enclosure, or switch to a filament that doesn’t split like ABS tends to. poor interlayer adhesion due to low temperatures, and uneven cooling leading to layer warping due to uneven contraction are the main causes of issues with ABS and all printers regardless of make or model will show similar issues with ABS. You can actually salvage that part with some plastruct plastic weld and some squadron model putty and paint if that will suit your application.