Struggled for over a day with IntelAndroid-FBRL-01-17-2015, IntelAndroid-FBRL-05-16-2015-PTR, and IntelAndroid-FBRL-06-03-2015-PTR2 on my Acer A1-830 with an un-updated ROM (4.2.2, 3.4.34, Acer_AV052_A1-830_RV04RC01, build 0.009.05). I had minor success using T4 on the two latest scripts, CWM and TWRP, but in both cases, I was failing to mount my external SD card, and other critical directories, so could not install the su binaries.
I finally came back here and ran the Mykit stuff on page 1 (http://forum.xda-developers.com/show....php?t=2681783
I suspect that the drivers I was using for the ADB tether were part of the problem. I used Mykit to update them. The other ones I was using were from Acer, so I figured, "how can they be wrong?"
Anyway I ran Mykit_BATCH twice--didn't take the first time. Second time I tried to root, using the SDC_INTEL2_ROOTKIT, it rooted with no problems.
If and when I un-root, I will test the newer scripts again with the updated driver to see it that was the issue.
Have some caffeine on me...