Hi Henry,
Thanks for the response. I tried the same with PANGU , when the phone is getting restarted by PANGU app the phone is going to DFU mode and again I need to jailbreak as it's tethered and then when the PANGU session continues it's getting either timed out or getting "Jail break failed" error.
For the time out issue : I tried a workaround having two pcs one with PANGU and another with tethered jail break app, as soon as the device goes to DFU mode I will disconnect the USB from the PC running PANGU and connect it to the PC with the tethered jail break app . By doing this I will bring back the device from DFU to normal and connect it to the PANGU , now timed out is getting fixed but getting Jail break fail error at the end.
It's so confusing to know the exact reason

. Stuck . I came across something on a different forum for ios 6.x where by installing the evasion from cydia is converting the tethered to untethered but for 7.1.2 in Cydia I can't find the evasion

.
Thanks,
Goutham