Blued and syslogd Eating CPU and Flooding system.log

Solution 1:

Blued and syslogd are both daemon processes. Blued is your Bluetooth daemon process and syslogd is is your logging console daemon (crash reported, console log files etc). Blued is connected to your console daemon so I guess that blued is actually the cause of your problem while the syslogd issue is only a result of the blued's problems. Looking at the error it seem that there is an communication error and your blued process is just waiting for a response from a device. The error is that your blued command is your host communicator interface (HCI) and an request is send but without a response. It's weird that blued waiting from the kernel from a response it putting it in a 100% CPU state.

1. Disconnect every bluetooth device in your device list and turn off every device that tries to connect to your Mac. Now re-connect every device again to your mac.
2. Remove all bluetooth caches
   1. Turn off bluetooth
   2. Remove /Library/Preferences/com.apple.bluetooth.plist
   3. Remove ~/Library/Preferences/ByHost/com.apple.Bluetooth.*.plist
   4. turn bluetooth on again
3. If you turn bluetooth off from the bluetooth menu, does blued eat less cpu? If you turn bluetooth on or off the blued keeps running. If the blued keeps running normal when bluetooth is turned off it could be an hardware issue
4. Did you update the bluetooth firmware up to the latest version as well as your mac OS X software?

edit: option 5, it could be caused by cheap and crappy bluetooth hardware connected to your mac of course.

Solution 2:

FYI, I tried this today and it did help with blued taking up a huge chunk of CPU time, but the ByHost .plists have changed in Mac OS X 10.9 and now Bluetooth is capitalized, ie: ~/Library/Preferences/ByHost/com.apple.Bluetooth.hhhhhhhh-hhhhh-hhhh-hhh.plist (h is hex values)