Hi. This issue is driving me crazy. I've been looking for more information but I've only found this thread, a CyanogenMod jira bug (look for issue BACON-115, I can't post links yet), and an issue at Android Open Source Project issue tracker (look for Issue 72311: GPS losing satellites - Nexus 5 - 4.4.3 and 4.4.4)
I first found the jira bug, so I tried the gps.confg settings referenced there, after that the issue was slightly (very little actually) less annoying but the GPS still got lost very frequently, I believe those settings just improved locking/fixing times a bit.
Then I started tinkering with my settings while driving (in stop lights of course, not while actually moving
) and I noticed that as soon as I turned mobile data OFF, the GPS locked immediately and never got lost from work to home (a 30 min drive).
So I started querying Google for things like "GPS lost while mobile data on", after about an hour I got the bug in code.google.com, which suggests it's only happening while 3G data is on, not while 2G. And it is, I can get a constant GPS fix while on 2G. The bug thread hinted about flashing different versions of the radios to find a version that works.
I remembered that with OPO firmware 25R this issue was far less annoying so I went ahead and flashed only the radios from 25R. It was not completely fixed, but my yesterday commute got significantly less GPS signal loss, and when it got loss it took less time to fix again, which I attribute to the gps.conf from the jira bug.
I've experienced this issue with 30O and 33R firmwares and with CM Nightlies (which I'm using right now), but slightly less annoying with 25R. Flashing 25R radios and using the modified gps.conf alleviated the issues a lot but I still get frequent GPS signal lost. Turning off 3G will definitely make GPS fix/lock constantly.
I wonder if there are older radios that could get rid of the issue completely (and what drawbacks using older radios could bring), meanwhile I'm using Tasker to fall back to 2G as soon as I'm connected to my car's bluetooth AND Waze is opened, so that I can get a constant GPS fix/lock while driving.