YAr my car LIANA LXI CNG has also developed the same problem I guess after the 5000km service. In this service the suzuki guys did the tuning and also some adjustment of the black slab behind the battry.
"All it needs is an adjustment of one of the CNG devices (dont know the name of the exact part). Its located a little behind the car battery and looks like a small black slab. Anyways, just needs a little adjustment and all will be fine. "
Did he adjusted the pressure of CNG ? In my case he was adjusting something with screw driver and looking at the pressure on the computer. He adjusted it to make it 2.3bars from 2.43bars. I dont know whats this abt.
But pl. tell me that did it really solve the problem? and also my engine has been washed once with water at the service station .Could this be the reason for the problem?