sorry guys I work on new cars for a living, you dont use water any more it leaves rough edges on the pistons BG makes a cleaner that is 2 part. Part one you slowly drip in the intake system about 1500 rpm till the can is empty, you put the second part in the fuel tank 20 gal per can
GM also makes a great top engine cleaner if you can find it.
if you are having problems on yor new fuel inj. car try cleanig the intake system,
they are finding carbon deposits on the back of valves cause problems
If you want to use water make it hot as possible and add ATF
