Failing slow extrusion after upgrade to E3D hotend I recently upgraded to a E3D full hotend and I started to have problems with slowly printed parts. After I print first object and start next one, then the first layer has serious issue.



The first two test were extruded around 10mm/s, the right one around 15mm/s. The material is PLA (fillamentum.com) at temperature 210°C and nozzle diameter is 0.4mm. The Rebel II RepRap printer uses RAMPS with marlin firmware. I use Slic3r and Pronterface SW. 

I didn't find answer in following troubleshooting guides:


Simplify3D - Print Quality Troubleshooting Guide
A visual Ultimaker troubleshooting guide
RepRap - Print Troubleshooting Pictorial Guide
all3dp.com - 16 Common 3D Printing Problems (And Solutions)


Do you have an idea what can cause this issue?

Update

I did a new print, where I just heat the hotend and start printing immediately. This is the result:
I bet your old and new extruders have different hobbed pulley/bolt effective diameter.
It looks like your new extruder has smaller hobbed diameter that's why it pushes too less material.

In MatterControl application there is a slider which allows user to tuneup extrude ratio on the fly (while printing). You coud check it so it would confirm the issue.

In Slic3r you could go to

Printer Settings > Advanced > Extrusion width

and experiment with it (especially with Default extrusion width)

Both (Slic3r and MC) could answer your question if it's extrusion ratio issue. If you confirm that - you can proceed with calibration. Here is method to calibrate extruder flow and general calibration article here.