The secret process that I used was to fill the resivior of my Bosch diesel nozzle tester with a mix of Marvel Mystery Oil and Techron fuel addative (it was for carburetors back then), and pump the contents through each of the injectors. The diesel tester has a higher pressure and volume than the gasoline injector tester and woud do a nice job of flushing the junk out of old injectors. The set of injectors in my car now are the best 6 of a bucket full of old injectors that I had accumulated. Before any one asks, no, I don't have this bucket O' injectors any more.