I have issues with pyobd too.

in terminal i can issue:

atz
ate0
0100

and get proper responses, but i get ERROR replys in pyobd.

My device (ELM327) came only today, but from the test i have done so far, carman works OK. (it seems to also open up rfcomm line).

Nokia-N900:~# /opt/pyobd/pyobd_start
Searching for BT dev...
-Found device: vanek-0 (00:03:7A:A5:B6:AA)
Found BT SPP dev
Can't open BT serial port
-Found device: Parrot 3400LS (00:12:1C:A6:00:6E)
Found BT SPP dev
Can't open BT serial port
-Found device: CHX (00:11:12:19:11:33)
Found BT SPP dev
/dev/rfcomm0
Send: atz

self.state: 1
Send: ate0
ate0
Send: 0100
BUS INIT: OK
Send: atz
ELM327 v1.4
self.state: 1
Send: ate0
ate0
Send: 0100
BUS INIT: ERROR
Send: atz
ELM327 v1.4
self.state: 1
Send: ate0
ate0
Send: 0100
BUS INIT: OK
Send: atz
ELM327 v1.4
self.state: 1
Send: ate0
ate0
Send: 0100
BUS INIT: ERROR
Send: atz
AZ
self.state: 1
Send: ate0

This goes on forever and no data actually pass into the software... any idea?

EDIT:
Nokia-N900:~# aptitude show pyobd
Package: pyobd
New: yes
State: installed
Automatically installed: no
Version: 0.9.2-12