is it safe to pressure wash your engine and should i wash it with the motor running or off.

I would not do this. Just think of all the places the water can be forced into. all the vacum hoses and wires that can be knocked loose. There are instructions on the se-r.net site. check them out:
http://www.se-r.net/car_info/clean/detail_engine.html

never do it while the engine is hot!

Originally posted by ser_lover
never do it while the engine is hot! \

Yup, I learned my lesson. I fucked up a lot of sensors and fouled my spark plug. Do it right everytime. Peace

I've done it with the car running before....nothing happened...what happened to you? I'll take the advice though...engine off.

Cover your valve cover and distributor with a folded towel and use the low pressure soap(regular soap as I have had problems with the degreaser) and use the low pressure rinse to get the soap off. I have done this for years with no problems. You can detail the valve cover by hand. Definitely clean it with the motor off.

BTW, what does "fouling" a spark plug mean??