LPG, Lambda sensors 1997 disco

Hi All,
I an new to your great forum.
I currently have a issue with my 1997 3.9i v8.auto.
I have taken off the lambda sensors and cats, when I changed a few exhaust parts [downpipes and y piece]
But I am having problems, with the lpg,when I go into top it starts spluttering , coughing and a few blow backs from the snorkel air filter.

I changed the white tune resistor to a green one, so this has sorted the petrol side of the ecu,
But I have obviously missed something, does the lpg ecu side need to be retuned or altered?
I do not have any problems when it runs on petrol.

I can't really afford to take into a garage .
And I don't want to put sensors back on.

Thanks in advance, Chris.

The sensors provide info to the ECU that proper air fuel mixture has been made, without that signal from the Sensors you are probably effecting how the ECU maps out the air fuel mixture on the LPG side.. it may be doing the same on the Petrol side it just may not be as noticeable except in fuel economy.

Hi Joey,
I appreciate the role of the lambda sensors, is to tell the ecu what the mix is doing, and it adjust accordingly . but as I am running on gas, I have been able to take the catalytic convertors off . for the European market, the ecu uses a white tune resistor, which tells the ecu to communicate with the lambda sensors, because the Saudi Arabians didn't need cats, they used a green tune resistor, which tells the ecu to ignore the lambda sensors and run off a set mixture, I appreciate this is not as efficient , because the ecu is working off a fixed setting, as apposed to varied signals from the lambda sensors. the green 470 ohm resistor is fitted, and on petrol she runs a dream, because the gas injection system is separate from the car system, I now need to find the equivalent fix for the gas side.