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RX-8 Carbon Issues

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Old Feb 14, 2010 | 09:05 PM
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RX-8 Carbon Issues

Hi, bought an rx8 and was just wondering if you guys had any suggestions on how to keep the carbon from building up and causing carbon lock? Some guys say to blast the engine out with a little water while reving it up will blow out and break up the carbon. What do you think?
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Old Feb 14, 2010 | 09:16 PM
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No, search in the diy for carbon cleaning procedure.
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Old Feb 14, 2010 | 09:17 PM
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When I feel there is a little hesitation in the engine I add a can of Seafoam(Walmart $8) to a half or quarter tank of gas and give her hell.
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Old Feb 14, 2010 | 09:18 PM
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/\ +1
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Old Feb 15, 2010 | 11:31 AM
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This stuff you get at walmart, is there any certain miles you should drive when adding it? Meaning how often do you recommend doing this treatment.
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Old Feb 15, 2010 | 12:04 PM
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Originally Posted by Old Rotor
When I feel there is a little hesitation in the engine I add a can of Seafoam(Walmart $8) to a half or quarter tank of gas and give her hell.
That really works?
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Old Feb 15, 2010 | 01:38 PM
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Some people have suggested using Lube Control FP Plus to minimize carbon build-up over time. I just ordered some of this stuff myself to try out.
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Old Feb 15, 2010 | 02:13 PM
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Pre mix

Start running pre mix check the thred on it
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Old Feb 15, 2010 | 02:54 PM
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Originally Posted by jmc23200
^ FP+ is potent stuff and the bottle leaks a bit during shipping. It requires 1 oz to 10 gallons of fuel. I used a dixie cup to measure it(3 oz dixie cups) and it ate through the cup lol.

Seafoam is safe for your engine in the gas tank every once in awhile. BG 44K is also recommended for this procedure. Do not over use either as it will attack the oil films in your engine. Putting a bottle in a half tank of gas then driving hard should be fine. Maybe throw in a little extra premix while your at it.
How long did you use FP+ for? Notice any difference? Do you add ~1oz before a fuel fill-up?
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Old Feb 15, 2010 | 03:31 PM
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Originally Posted by jmc23200
I just started using FP+ but I won't notice a difference any way as I have a new engine. I added 2 oz before fill up the first time(shock treatment recommended on bottle) and then 1 oz before fill up after that. At 1 oz per 10 gallons of fuel, I think that this is a slow cleaner. Slowly removing carbon while not damaging the oil films. Who knows what it actually does.
Thanks for the info. My order should arrive later this week and I'll start with a similar procedure.
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Old Feb 15, 2010 | 03:50 PM
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I always drive to empty (except on the track), and then I add 7oz of premix before I fill up to make sure it gets good an mixed. I will be playing with some different premixes (still running Lucas 2 stroke for my SOHN for now) and I will see what smokes and what doesn't.

Smoke is an issue for me as I am catless so it is worse when premixing 2 stroke. I don't smoke hardly at all running the Lucas UCL as premix.
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Old Feb 16, 2010 | 01:10 AM
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Water/Methanol injection was used during WW2 on airplane engines to help prevent carbon buildup on surfaces within the cylinder, as well as on some earlier SAABs (probably the 2-strokes?). A few people on this forum have added such a system to their 8.
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Old Feb 23, 2012 | 05:59 AM
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I have hot start problem due to low compression, if i do seafoaming will there is any chance to increase the compression..
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Old Feb 23, 2012 | 07:12 AM
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Maybe.
Maybe not.
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Old Feb 23, 2012 | 11:34 AM
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If you do seafoam the proper way and not just add to the tank, you might get some extra compression. Just don't expect miracles like going from 6s to 8 or 9 or more. Do a search or look in the diy forum for seafoam or mazda zoom zoom cleaner.
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Old Feb 23, 2012 | 11:41 PM
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well se3p s look at it this way. take an hr or so out of your day and 10 bucks and try it, or spend 100's at the dealer figuring out why it wont hot start, or spend 1000's replacing a motor lol. i'd start with the seafoam. I did but it didn't help my hot start issue. Although i didn't let it sit long enough due to time restraints. Hot starting could be many issues not just low compression although its probably most common but also most commonly mistaken is a failing starter, battery, ignition plugs/wires/coils....unless you have tested and found out you do have low compression. In which case i'd do a seafoam treatment probably once a week for a month with premix. If it aint better by then best of luck. join the new motor club. or my club the im to poor to afford a new motor and am past the 100k mile warrenty and owe to much to sell it in bad shape club.
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Old Feb 23, 2012 | 11:43 PM
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also known as the SOL club, and Screwed club, a second cousin to the up the creek without a paddle club, and shtf club.
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Old Feb 24, 2012 | 12:08 AM
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Originally Posted by 9krpmrx8
I always drive to empty (except on the track), and then I add 7oz of premix before I fill up to make sure it gets good an mixed. I will be playing with some different premixes (still running Lucas 2 stroke for my SOHN for now) and I will see what smokes and what doesn't.

Smoke is an issue for me as I am catless so it is worse when premixing 2 stroke. I don't smoke hardly at all running the Lucas UCL as premix.
What oil would you stay away from due to smoke?
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Old Feb 24, 2012 | 01:03 AM
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ISO-EGD oils don't smoke, it's part of the standard.

TCW will smoke like a Frenchman.
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Old Feb 24, 2012 | 08:04 AM
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if you are low on compression but the car still runs, just a hot start issue, then maybe try pre mix oil at 1 1/2 to 2 ozs per gallon of gas. Dont do this if you still have a cat.
It may help a little. It will not hurt anything and it may buy you some time.
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Old Feb 24, 2012 | 10:02 AM
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Originally Posted by olddragger
if you are low on compression but the car still runs, just a hot start issue, then maybe try pre mix oil at 1 1/2 to 2 ozs per gallon of gas. Dont do this if you still have a cat.
It may help a little. It will not hurt anything and it may buy you some time.
What I will premix 2t or seafoam?
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Old Feb 24, 2012 | 10:49 AM
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ive had a hot start issue for 2 years lol.. although my case my not be typical.
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Old May 28, 2012 | 06:52 PM
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In regards to seafoaming properly would it, maybe, raise compression from 7.9-7.7 to 8.0ish?
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Old May 29, 2012 | 01:01 AM
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I increased my premix to 1 oz/gal since having issues with hot-starts last month. I have replaced everything I can (ignition, battery, starter...) within the last two months. However, the engine haven't had any de-carboning treatment in all it's lifetime. I'm curious to find out what the seafoam through the tank will do, but I also believe that the low compression I have might get worse if I decarbon the engine. I hope my theory be wrong once I try the seafoam this week.

Last edited by Grace_Excel; May 29, 2012 at 02:17 AM.
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Old May 29, 2012 | 06:14 AM
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nothing will save your engine if the seals are simply worn out.

doesn't hurt to try, but as our car age, we will see more and more issues down the road
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