Well, I did another 1/6 of a can. This time the vacuum line spit back at me and the engine died. Started it back up, no problem. Backfire? Getting kind of nervous about what exactly that was.

I can't help but wonder if I did it wrong. I find it so hard to believe that there was that little carbon in my engine. I would've thought that the Seafoam itself, even if no carbon, is supposed to create a huge amount of white smoke.

Here'* a photo of the vacuum line I used. The red line runs alongside the line, and the arrow points to where the line was disconnected and the Seafoam fed in.

That spot is fine.

Mine didn't smoke much at all, Ilike to think of it as a sign of a fairly clean engine
Our Mercury Grand Marquis smoked so bad neighbors came out so see what was on fire. LOL

Did it again with a 1/3 of a can. This time I used a funnel and fed a little bit in at a time over the course of 4-5 minutes. Pretty strong cloud of smoke for 10 seconds, then the exhaust was clean. Does the speed with which it'* fed have an impact on how much smoke billows out?

A person from my forum questions the use of the vacuum line going to the TB. He says I'm not getting results because of that and I should be using the line to the PCV valve.

Are you giving it soak time? The idea is to feed it in, shut the engine down (if it doesn't stall), let the Seafoam soak into the gunk you want to remove, and start the engine up again. I have not done this myself, but I would imagine you would need at least a half hour for soak.

The can says 5 minutes. I gave it at least 15.

I'm kind of loath to try it again... I've already done 2/3+ can in less than 24 hours.

Ideally...inject 1/3 of the can inot the motor via a vacuum hose near the throttle body, let the engine sit for 15 minutes or so. Pour the remainder of the can into your gas tank. After the 15 minutes are up, start the car and let most of the smoke clear. Warm the car up and take it for a drive with a couple of WOT thrown in for good luck!