Water De-carb

[fnlyfnd]

I gotta say I am kinda scared to do this. I'll be doing it next weekend when I am home (parents) where all my tools are. I have been running 93 after relocating the knock sensor. It's like a new car with that setup. But, today i put in 89 and the cars is pinging under heavy load. I've seafoamed a couple times, fuel injector cleaner a couple times. Apparently they didn't help, so I am going oldschool and using water. I got this idea from Blitz in a thread from awhile ago. Thanks Blitz.

 

Should I change plugs or oil after doing this? I know to keep the engine running after I am done, and take it for a ride.

[porcupine73]

This is a tried and true method. Just don't let her drink the water in too fast. On '00obw I replaced knock sensor with a resistor, and even with 93/94 it is pinging somewhat under full throttle.

[OB99W]

Removing combustion chamber carbon with water is indeed an old technique. It does work, up to a point, but isn't without risks. As has already been mentioned, introduce the water at a reasonable pace. Keep the engine revs up to prevent stalling and to minimize the chance that a chunk of carbon will lodge in a plug gap or exhaust valve.

 

 

Should I change plugs or oil after doing this?

Plugs, only if an ignition misfire develops and doesn't clear. Oil may or may not become sufficiently contaminated for concern, but I'd be inclined to err on the conservative side and change it.

 

If a one-time treatment doesn't do the trick, perhaps a water-injection system might help with knock while continuing the cleaning process.

 

While not specific to Subarus, the following might be of interest:

http://www.saturnfans.com/forums/showthread.php?t=73236

http://www.rallycars.com/Cars/WaterInjection.html

http://www.hackaday.com/2005/06/25/home-built-water-injection/

http://users.frii.com/maphill/wi.html

http://supersoda.com/detail.php?id=00000000075

[Towel Rail]

In the old days, they used to pour in a little diesel fuel to burn out the carbon, but that couldn't be good in a fuel-injected, computer-controlled modern engine.

[ericem]

Why not just use seafoam the safe way?

[fnlyfnd]

been there done that a few times

 

Water is safe, just as guns are safe. It all depends on the user

[jib]

I've used a spray bottle. It's hard to add too much. Cleaning may take a little longer though as less water is being added at any one time.

 

Jack

[WoodsWagon]

Or, this is a novel idea, REPLACE THE KNOCK SENSOR! If you have a good knock sensor in the proper place and oriented correctly on the block, your detonation will go away, you can run any grade of gas you want and all will be well with the world.

 

The sensor can fail to being too sensitive and trigger at anything. Replacing it with a new one will fix the problem. Believe me, I have been down this road. I relocated it, which was all well and good until we had to tow a trailer, at which point it detonated like you wouldn't believe. I swapped on a sensor from one of my spare blocks, in the propper place, and it's been perfect ever since. It gets better milage on 89 than 87, which means that the timing is compensating for the signal from the knock sensor, which is what it's supposed to do.

[LosDiosDeVerde86]

I gotta say I am kinda scared to do this. I'll be doing it next weekend when I am home (parents) where all my tools are. I have been running 93 after relocating the knock sensor. It's like a new car with that setup. But, today i put in 89 and the cars is pinging under heavy load. I've seafoamed a couple times, fuel injector cleaner a couple times. Apparently they didn't help, so I am going oldschool and using water. I got this idea from Blitz in a thread from awhile ago. Thanks Blitz.

 

Should I change plugs or oil after doing this? I know to keep the engine running after I am done, and take it for a ride.

 

you should probably inject the water in aerosol, rather than pouring. it'll be safer that way.

 

every seen the movie "Abyss" when they have to "breathe" water to go down to a certain depth in the ocean? yeah...your body says no, no matter how hard you try.

 

just be careful and don't flood the thing

[Towel Rail]

Or, this is a novel idea, REPLACE THE KNOCK SENSOR! If you have a good knock sensor in the proper place and oriented correctly on the block, your detonation will go away, you can run any grade of gas you want and all will be well with the world.

 

x2. You shouldn't have to run 93 to keep it from knocking.

[fnlyfnd]

Right. But If I have carbon buildup then a knock sensor running 87 will jst pull timming, buck and stumble (and also save my engine). Running 93 with a knock sensor wouldn't pull timming, buck or stumble...I found out by re-locating my sensor, that I am pinging. Hence the reason I wanted to do a water Decarbonization. I didn't do it when I was surrouned with all my tools (at home last weekend). I am not going to do it. The car is running beautifully with 93 and a re-located knock sensor. Hopefully running this for a couple months will clear it up.

[lmdew]

I use the Off bug spray bottle, the thin plastic one, pull the pump nozzel off and there is a 1/8 or so straight fitting, that hooks to the vaccum line perfect. I keep the bottle level or hose up slightly and let the vaccum pull the water out until the bottle is sucked flat.

 

Works great.