Infill failure when printing larger prints I'm new to 3D printing an I just got a Creality Ender 3 and I think I'm getting some good results with small prints. However, now that I'm trying some bigger prints and I'm running into infill material excess. In the picture below I just printed a solid cube with 20&nbsp;% infill and that's the result.

I have been playing with settings a lot but I'm really running out of ideas.
These are the settings I have:


my bed, fortunately, came in pretty flat. My first layer is always very good indeed
bed level method: paper method
Slicer: Ultimaker Cura
material: PETG (Amazon basics)
layer height: 0.2&nbsp;mm
nozzle temperature: 230&nbsp;&deg;C, but also tried 220&nbsp;&deg;C and 210&nbsp;&deg;C
bed temperature: 90&nbsp;&deg;C
flow: 98&nbsp;%, but also tried all the way to 90&nbsp;%
cooling: 0&nbsp;%; the issue got a lot better with some additional cooling but I see a lot of people printing with no cooling 
infill density: 20&nbsp;%
retraction: on, 5&nbsp;mm
retraction speed: 40&nbsp;mm/s
first layer print speed: 30&nbsp;mm
print speed: 50&nbsp;mm/s
wall speed: 50&nbsp;mm/s
infill speed: 50&nbsp;mm/s


Let me know if you want to know more settings, but I think these capture most of it.

If you guys have any suggestion on things I can try that would be of great help.

UPDATE

After playing with some settings these are the changes I think I'm settling on:


Flow: 105&nbsp;%
Coasting: On, 75&nbsp;%
Cooling: 60&nbsp;%
Retraction speed: 50&nbsp;mm/s


Here is a picture of when the infill issue starts:


NEW ISSUE

Now I'm getting a lot of stringing. Actually, I don't even know if it's stringing since I ran a test and came out basically perfect. Not a single stringing.
I'm getting a lot of material that get dragged when the nozzle moves to one place to another and a lot of material accumulates on the nozzle and slowly drips everywhere during the print.
 

Here is a video I made (not sure if it helps at all)

https://www.youtube.com/watch?v=tlIB1WW8z84&amp;feature=youtu.be

I think I'm getting close to have good prints but I really can't figure this out.
I have seen this a lot with people I have helped out in the past. sally infill  or the lack of and weakness in the print is due to an extrusion issue. it looks like you are under extruding. this is why you do not see this in smaller prints. In the larger print you are giving the print head enough time to screw up. You need to look at the tension of the filament on the extruder to make sure it isn't skipping. You also need to do a estep calibration on the extruder. I usually extrude 100mm of filament and measure it to see if it is short. if it is short then it is under extruding and doing a larger print and printing a larger area will reveal short comings in extruder infill.