I recently did an induction Seafoam treatment on my 194K mile old WJ 4.0. I used the tube that came with the can and tucked it into the rubber coupling as instructed. I got very little smoke because the head and valves are fairly new but I wanted to clean the pistons and intake manifold. I wound up screwing up the TPS! Apparently the shaft seal was shrunken and allowed the Seafoam to enter it and short it out. After doing the treatment, I ran it down the road at high rpm in a lower gear and gave it short bursts of almost wide open throttle. It seemed to be smoother and more responsive, but wouldn't idle. If you started it without touching the gas pedal, it idled okay, but raise the rpm a little and let off and it would drop below idle and stall. I got a P0123 and a P0121 code. "TPS voltage too high" and "TPS voltage does not agree with MAP"

I had to drive it for 2 days until I got a new Mopar sensor and if you once put it in gear, it would run okay on partial throttle, but give it a little too much and it would stutter and jerk violently at times and it wouldn't shift into O/D at all. If you let off on the throttle just as it was going to shift, it engaged with a bang.

After I put the new sensor in, it was perfect and shifted into 4th with no problems. All the other shifts were normal also. Checking the seal on the old one and sure enough, there was a very small gap under the seal.

SO, I guess nothing but air is supposed to flow thru the throttle body, huh? The Seafoam also softened the rubber elbow on the vacuum line to the purge solenoid. From now on, I'm sticking with water!

 

I'm pretty sure sea foam is pretty bad for the cats too. May not be as big of an issue on pre 00/ non CA emissions vehicles but I've read several times that sea foam harms the small pre cats used on the 00+. Something about the precious metals used for catalyzing get destroyed.

 

Plain old H2O is all you need for combustion chamber. Carburetor cleaner for air intake.

 

The worst part about this whole deal is I had never heard of Seafoam until the guys on this forum said it was the wonder drug for 4.0s! So I bought a can but my 0331 head cracked before I got to use it, so it sat on the shelf for awhile. This engine has 195K miles on it with all original sensors, so I'm expecting them to start self destructing any time now! Besides replacing the head, the only repairs I've done to the engine was a water pump! I've been lucky! Very! I'm an old guy, so maybe I don't whamp on it as much as you guys. Don't get me wrong! I used to drag race, but this is my DD and used to make a livelihood.

 

I use seafood twice a year in my cars. Third of the can in the gas. Third in the oil. Third through a vacuum line(preferably one centered in the intake never through a throttle body.) And it works like a charm. I do this on my jeep which is a 98. Same on an 03 explorer. 06 hyundai. At the shop ive seen it used on 2010+ beamers with direct injection. Never screwed any of them up no faults no glowing cats. I'm guessing if seafood caused a problem it's probably likely it was used wrong (you seem smart enough to follow directions) or given the failure rate of tps sensors it was already weak and cleaning the crud from it caused it to fail.

 

I think I made the mistake of buying an aerosol can with a tube that goes into the air filter hose, thus spraying directly on top of the throttle plate. Even doing it that way, I should have used a vacuum port in the manifold instead, like the one in the side directly under the throttle body. That's the one for the canister purge solenoid.

 

Yea I haven't seen an aerosol one yet. There are apparatuses out there that's basically just a container with a metering valve on that you hook up to a vacuum line and it drips in at a set rate. It takes a while for it this way but by metering it a slow drip rate you limit your chances of damaging the cat.