[MATCHBX]

Simple green works about the best for not having to put alot of elbow grease into it. I squirt down the entire engine, everywhere, and let it sit for a few minutes. Then hose it off with a garden hose (or small pressure washer). Then you will want to grab either an air hose with a nozzle or what also works is a leaf blower. Blow all the standing water off of the engine with one of these. Then you will want to mix up a 50/50 mixture of Armor All and water and squirt the whole engine, hoses and all. Let that sit and your engine bay will look better than showroom quality (except for some of the rusty parts). We did that with my ex's car and, as anyone who saw it can attest to it, it was one of the cleanest engine bays they ever saw. We never wiped anything off or even touched the engine bay with a rag. That is how easy it is.

I'd say make sure that you at least cover the air filter. If the car won't be started for a while, then cover the alternator and such. Otherwise, just let it sit for a while and start it up to make sure everything works ok. We never had any issues with our cars as far as electronics from doing this. We never covered them. Just try not to spray too directly into them and you will be fine.