Expect some questions to be about MEP planes in general and some specific to the model of plane you will be taking the test in.
I lost some valuable marks by not knowing the tyre pressures. One question asked for the nosewheel pressure and the other, the main gear pressure. Can't imagine why I need to have these figures committed to memory though.
Also expect quite a bit on asymmetric flight.
There were some questions that were not specifically MEP. For example, which magnetos, are connected to which spark plugs.
Good luck!
AP