[rjacob]

Anybody ever use one of these 3-part engine cleaners which are supposed to remove carbon from inside the engine? I had it done at a Valvoline Oil Change place a few years ago, and a crap-load of smoke came out of my car when they were doing it. It was supposed to be the carbon being removed. I found some DIY kits online. Do these actually work and improve performance, or are they all smoke and mirrors...or more smoke? If they work, does anyone have recommendations for a good one, or are they all similar? My car currently has about 184,000 miles on it, and my mileage isn't as good as it was a couple years ago. I did a basic tuneup (plugs, cap, rotor, air filter), but not a big difference. Have used fuel-injector cleaner stuff. Mileage still down.