Northstar Engines and System Technical Discussion Discussion, Washed My North* in Cadillac Engine Technical Discussion; I own a 99 STS w/106K miles, just yeterday i washed my engine with the Black Magic engine detailer. Now ...
You probably filled the spark plug holes with water.
Did you use a pressure sprayer?
You can pull the plug wire boots out of the valve covers, but you'll need some compressed air and safety glasses (or something to protect your eyes) to clean them out.
Don't worry, you are not the first person to do that.