i came to hear from different peoples that for smooth startup of CNG vehicle in Winters follow these steps:
1) when u plan to park vehicle at night.
2) Close valve near to cylinder.
3) then keep start vehicle until all gas in pipes finishes.
Now car automatically stops when gas finished.
Next Morning Open CNG valve, and turn Key to ignite ENGINE.
Hopefully car will start easily.....
i confirmed this from more than 10 users....