Is the 1.4V N-G with the transformer unloaded and then it goes to 17.5V with loading applied? Is so that would be due to voltage drop on the neutral conductor from carrying the load current.
Or are you comparing the N-G voltage before the transformer and after the transformer when it's loaded in both of those measurements?
If it's the second case you're probably boosting on the neutral side instead of the line side. Measure from the line input of the autotransformer to its line output. You should see the amount of voltage boost. If the voltage measured across the line in and line out is very small then you may be boosting the neutral side instead.
It is 1.4 at the ped. in front of the transformer. 17.5 after the transformer. Very light load. Just the RV converter and a TV. Transformer is spliced into the RV shore power cord. I can not plug in without it. I need to now the safety ramifications of this 30 volt difference between L1 and L2. Also is there an KWH cost involved this as I am paying the electric bill? Not much transformer knowledge. 50 years residential experience. not much use for transformers.