Bowlcut is right. You do need to cover up ALL the electricals. I use small plastic shopping bags. I bag everything. Distributor,relay/fuse boxes,TPS,MAF,etc. Then I'm real careful about how close I let the nozzle get to bagged items. After I finish I take a shop vac and vacuum up excess water in the engine compartment, then I let the motor run for several minutes to dry everything off.