we are testing a completel different gas to run the natural gas generator engine. biomass gas. wood gasifier. the throttle body on the engine already is controlling the amount of fuel to the pistons. we are trying to control the mixture ourselves for experimental/data logging purposes. The natural gas engine is generally controlled by a pressure venturi system. we have removed that as our system does not function in this fashion. we function off of vacuum. we have already successfully done this on a ford 351 van and run it across the US three times on wood. essentially the same engine minus two pistons. however we manually controlled the mixture via a choke lever. we need to eliminate this and have our automation system handle this completely. in order to do this i simply need to measure the excess o2 for our sweet spot. then input the data for our PID loop for our mixture throttle.