UPDATE:
http://www.seafoamsales.com/
Above is the link to seafoam's webpage with specific how to instructions. Added info is use of SEAFOAM SPRAY if it is unknown whether your selected PCV line evenly distributes throughout the engine. Also, do not spray SEAFOAM SPRAY on your MAF sensor-you must detach the rubber boot and spray the throttle body.
There have been a few posts about seafoam and using it on our engines but I wanted to post the method that I have researched and personally use on my vehicle. I will write this up including other routine maintenance you can perform on your vehicle at the same time to aid in maintaining performance and increasing mpg.
Situation:
-2004 Sedan with 3.4 engine
-CAI with K&N filter
-High Flow Cat
-2.5" Pacesetter Cat-Back Exhaust
So we will begin with a purchased can of wonderful Seafoam cleaner.
First thing first: pour a 1/3 of it into your oil reservoir and a 1/3 in your gas tank. The purpose of this is to mix the cleaning agent with your oil and gas so it can circulate through your engine and work its magic as you drive around. I suggest doing this when you fill your gas tank and allow the oil to circulate for the mileage of one gas tank. Drive at all speeds so the oil can be fully circulated multiple times.
At the end of one gas tank it is time to administer Seafoam to your air intake system. While facing the 3.4 engine from left to right, the MAF sensor connects to black ribbed tubing which connects your your CAI piping. On the black ribbed tubing, locate the PCV plug located on top and remove it. This is where you will inject the Seafoam.
(Note: Being only a home mechanic I use a thin funnel in the opening where the PCV plug inserts. If anyone has a more efficient means of injecting a liquid please let me know)
With your funnel inserted, have a friend rev the engine to about 2-2.5k rpms. Pour the other 1/3 seafoam into the funnel at a rate that nearly chokes the engine but not quite. Too fast and it just drains down your CAI piping and too slow diminishes the concentration. The engine will stutter, sputter and throw a service engine soon light-all of these things are okay and temporary. It is just your car responding appropriately to the seafoam. If the car starts to choke out, give it a little more rev because the goal is to suck the solution through the throttle body and into the engine.
I do this when the engine is cool. The engine idles higher at cooler temperatures and seafoam is flammable.
(Note: I typically use 1/2 a bottle for the intake since I have an imperfect means of injecting it into the engine directly. It is compensation for losing some down the CAI tubing.)
Varying colors of smoke will emit from the exhaust. That is the seafoam doing its job. But as soon as the last of your seafoam is injected into the intake system, cut the engine off, re-plug the PCV and go to bed. Let the seafoam "marinate" in the engine overnight for ample de-carbonizing time.
In the morning, start it up and smoke and carbon will pour from your exhaust-but you have to fully flush the system with lots of air-in and air-out. Plan a trip with your honey that has some high speed highways to aid in this process. Drive it like a madman for at least half a gas tank to fully flush the carbon that has been broken down by the seafoam. Trust me when I say it is not enough just to not see anymore smoke coming from the exhaust-put some miles into it.
Seafoaming your intake system contaminates/dirties the oil since it cools and lubricates components of the combustion system. Oil is further dirtied by the cleaning via oil-added seafoam. In essence: an oil change is in order. But this is why it is important to fully flush the engine intake-if you do not, you will re-contaminate the clean oil from your oil change! Do not tell me that the seafoam solution makes the oil "slipperier" and makes things more lubricated. The purpose is the CLEAN your engine, why would your leave the dirty fluid inside to re-circulate!
Conduct an oil change and notice how your oil is quite dirty indeed. (depending on how often you perform these processes)
During or after the oil change, I like to clean my CAI filter (following K&N instructions and mileage/condition requires) and clean my MAF sensor (via How-to on Aleromod.com).
After the filter and MAF dry, re-assemble and add new oil/filter. At this time I fill up with a fresh tank of gas and add more seafoam (gallon:formula concentration on bottle) to the tank to top off the entire process. You can also add more seafoam to the oil crankcase for a longer, more thorough clean of your engine components.
With your systems flushed, clean oil, filter and MAF-sit back and enjoy better idle, performance and mpg.