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well, having heard the good reputation of sea foam for a while, I decided to give it a try.
according to the youbube "official how-to", I added it to engine oil, fuel tank and brake booster vacuum hose.
The first day had trouble to disconnect the brake booster vacuum hose, so I only sea-foamed the engine oil and

fuel tank, everyhting was fine, no crazy somke came out.
Today I decided to pursuit the brake booster vacuum hose anyway, so I managed to disconnect it, and sea-foamed it.
Some folks suggested I should slowly pour at first, and dump a lot all of the sudden to choke/soak whatever the

downstream engine component is. And that's how I did, and as expected, engine stalled. Fine, let it sit for half

and hour and let the sea foam do its job.Meanwhile, I reconnect the hose.
Well, after I started the engine again, the check engine light came on!!! WTF~~~ And I did see a lot of smoke,

well, that's comforting.....
It won't go off although I had no problem to drive around for 70 miles along with it on.
Being afraid of getting ripped off by dealer or even invalidating the warranty, stuff like that, I went to autozone

first.
And 3 codes were detected: P0300, p0302 and p0306, all of them are misfire.Well, I certainly didn't feel any

problem or misfire, which the autozone guy also agrees. So I persuaded him to erase these codes for me. After that

is done, the light came off, and so far not showing up again, I hope it stays that way.
So to sum up, I think when sea foam choked the engine, the misfire happened. No big deal. Please correct me if I am

wrong.
And 2 questions :
1, is the smoke due to burning carbon deposit or the sea foam I added? I use shell fuel injector cleaner every 7k

miles, and all ways the synthetic oil, it's hard to believe there still a lot of junk built inside the engine.
2, there's a check valve built inside the brake booster vacuum hose. Although it's for the purpose for air flow,

does it hurt the valve if we let any liquid go through it, as we added sea foam in the hose?
 

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The manual for my "other car" ( a ford Taurus) states at 7 different places not to use any additives whatsoever.

It's too bad Hyundai is silent on the subject.
 

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Yeah, I totally advise against the Sea Foam thing. It screws up the O2 sensors and the cat. Show me a reason why you need it.... bad MPG? Best to leave well enough alone.
 

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Agreed about Sea Foam; KC got horrible mileage (19) until I had her O2 sensors replaced; back to 25.1 on both the computer and pad & paper. :thumbsup:
 

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seafoam is great stuff, if used properly. I had a 2001 chevy Malibu with a 3.1 V6 that was running really rough and only getting 14 to 17 mpg on the highway. I did a tuneup to it including plugs, wires, air and fuel filters, changed the oil and filter. No change after that except for a bit more smooth while at idle. I seafoamed it by putting a whole bottle in with a full tank of gas, and a half bottle in the oil, and a half sucked in the brake booster hose SLOWLY skimming it untill it was sucked in. I then shut the car off and let it sit for 45 minutes. After that I let it smoke for a few then took in on a 45 minute drive to clear it out. This brought my mpg back up to 22 and it had so much more power and no more hesitation.
If you dump the seafoam in really fast you can hydrolock your engine and do some serious damage. I'm sure someone will dissagree but I have seen someone do it, and read multiple stories online of people doing it.
 

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First I saw that you added Sea Foam to oil. You should probably change the oil soon. I believe the directions are to add it to oil just before an oil change and then change the oil.

Putting small quantities as recommended in the fuel tank has no adverse effect.

As you learned, adding it into the intake through a vacuum hose (which is most effective) can cause temporary misfire with codes activated that have to be reset. I know that Subaru and possible some other car makers actually sell their own brand of essentially the same thing as Sea Foam and recommend it use as a "top engine cleaner." Based on that, I doubt that it would do damage if properly used.
 

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QUOTE (jsinton @ Aug 7 2010, 01:50 PM) index.php?act=findpost&pid=347831
Yeah, I totally advise against the Sea Foam thing. It screws up the O2 sensors and the cat. Show me a reason why you need it.... bad MPG? Best to leave well enough alone.
I would use such additives only if I had nothing to lose. If the car is old and running terrible, you could get
lucky. If the car is not old and running normally, you could get unlucky.
 

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I've used SeaFoam a few times on multiple cars, and have had the same issue... You seem to be spot-on, that it does choke the engine out... On some models I've used it on usually a few misfires are ignored; but you must have really been dumping it in there...

I think you should be fine, but agree with nds in that you should do an oil change after 30 miles or so - you don't want all the carbon/junk going back through your engine.

Also as Sleepy3103 said, you can hydrolock... I completely disagree with the concept of choking the engine out via the brake booster; that's just never a good idea...

To answer your stated questions:
1) The smoke is from carbon buildup... injection cleaners are going to clean injectors... not your pistons/etc... if you use a LOT of injector cleaner (along the lines of as much seafoam as you dumped in) then sure it'd clean some up, but it's not really made to do so. Synthetic oil or not, your engine will have carbon deposits.
2) That should be fine, as long as the vacuum is intact

A quick caveat, specific to what people are saying in regards to "that can mess up your car"...

There's a few key components that can fail after a SeaFoam, most of which are super easy to fix - but not necessarily cheap. In every case, it's the fact that you had so much crap in your engine, it essentially clogs up vitals.
Among them are:
EGR valves
PCV valves
O2 Sensor
Catalytic converter
Spark plugs.

Just keep your eyes peeled for these items, as they can be expensive.

[EDIT] Found the Seafoam article I was talking about... Even though it's for an Accord, it's still an excellent write-up and pictures (and applies to every vehicle): http://www.driveaccord.net/forums/showthread.php?t=20631
 

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DnB is right, the problems caused by seafoaming are usually because of the carbon being broke loose and clogging components. Don't for get IAC valves(idle air control valves) a buddy of mine had his go bad right after a seafoam, but we took it off and cleaned it out and soaked it in some seafoam and it worked again. The procedure I use is: half a can in the intake(slowly sucking it in) and let it sit for 45 mins. Half a can in the oil filler about 50 to 60 miles before an oil change. And a whole can in the gas tank with 12 to 16 gallons of gas. Works like a charm, I am going to do it right before my major services at 30k, 60k and so on.
 
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