@Uiv
Yes you are right, and the reason Ecu is unable to perform its limiting duties is coz of the emulator which is installed in Fuel Injected CNG. What the emulator does is fool the ECU into believing that the injectors are still operational. And Ecu controls fuel and air. Hence the car revs all the way.
But this does not mean it will not have speed governor. If it is equipped with one then the emulator would not be able to help.