Yea I mean nothing concerning yet. The LT and ST cancel eachother out at a sustained rpm. Could just be the stop and go driving ive been doing to/from work the past few days that isn't giving it a chance to settle.

 

will this help prevent a total rebuild?

 

Only if the reason for your low compression is that carbon build up has unseated the seals. If carbon build up has worn down the seals, or the seals have worn for another reason, or there is a coolant seal failure, housing warp, or broken seals, then no, decarbing will do nothing to restore lost compression.

Since you are planning on parting out anyway, it's worth trying a heavy decarb to see if you can restore it at all. It probably won't help, but there is a chance that it might....

 

Bump.
With recent discussions on this, I thought I would see if anyone has had any input on this recently.
It would be interesting if we could have anyone who will be rebuilding an engine soon contribute some more info on before and after de-carb treatment compression numbers.

 

I will be doing it. Hopefully either today or tomorrow. The numbers as of last week are 5.8-6.8. Currently doing research on which methods work and which do nothing at all. Maybe I'll just do all of them. Hopefully one of them works. I plan on getting another compression test in about a month or so.

 

That's good. If (when) I ever need a rebuild I will do the same.
I haven't had one yet, ignorance is bliss.
I'm thinking about doing it soon, just so I know.
'04 with just over 40k, bought it with 18k without a compression test.

 

Im sure you're still good. I'm an 05 with 88k original engine. It was working great before the last flood happened which took about an hour of very patient unflooding. It's still drives good but it takes it a bit longer to start and I immediately noticed the difference. Although it does feel as if it is getting better. Maybe it's trying to recover itself from all the stress it went through. If it's at all possible. Or maybe Im just getting used to it being different. Anyway I'll do a de-carb and do a compression teat in a month. And then I'll go from there.

 

I have read all the posts but did not get the answer to my question.
Do i need to take cat off or any other sensor before water decarbing ?

 

Ideally you should but when Mazda does the zoom zoom cleaning they don't. But it can't be good for the cat.

But it's still a waste of time.

 

lol I know its a waste of time but i just got my 8 and ducking love spending time with it (my wife hates it already for the same reason)
So I am thinking about mixing (since i am unable to find seafoam or mazda zoom zoom here) water, methylated spirit and some 2 stroke oil in a gallon of tap water (again cant find distill water any where near) and run it through one rotor at a time.
I will disconnect the Secondary Air injection pump to avoid any cat damage.
Anything I am missing ?
Also a very unrelated question. Some portion of my Air duct is cracked. From where its attached to the throttle body. its like a 1.5 inch crack. Rest of the duct is intact. Now a new one here will cost me 400 dollars and this thing is already running me dry. Will applying duck-tape over it keep the things undercontrol ?

 

Honestly wrapping it in duct tape will probably work. Since it's semiflexible a functional solution would be to coat the crack in a thick layer of E6000 on the outside only. Trashy, but it will work!

No reason to do the craziness, water will be just as effective for a decarb as that chemistry set.

 

So I was pretty excited today for this, Had a 2 hour seminar at work. Could not wait for it to get over so I can have sexy time with my 8.
I popped the hood open, prepared the gallon of water with 2T oil. Sadly when I started looking for nipples I was unable the find them. The pictures and diagrams are for a left hand drive. On right hand drive 2007 6 port A/t I cannot figure out where the nipples are. I looked around the Inlet manifold trying to decipher where they should be but sadly no success. I am attaching pictures of my bay.

 

Well to my utter disappointment my car is a 2007 a/t right hand drive. I could not see the nipples anywhere. I checked all around. For one my car has too many pipes obstructing as compared to left handed cars. Anyone can verify this for right hand drives

 

finally i was able to find these nipples on my JDM rx8.
I thought the nipple covers will be independent but thats exactly the opposite. The nipple covering is a t shaped pipe that has two arms, one for each nipple and the long arm of the T goes to the drain near your oil puring cap.
Once i took the pipe off, i could see the steel nipples.Did th
So I pre mixed some 2T oil in a gallon of water and treated each nipple separately.
Did the rear rotor First, went without a hiccup.
During the front rotor, the car switched off twice. All of a sudden it would get "out of breath" even with accelerator floored and die down. Then I had to crank it straight for 2 mins to revive it. I was fearing flooding though.
Any way once i was done
My idle rpm before decarbing was 1500
Idle after decarming is 1100
I have a manumatic 2007 with 38000 KM on the ODO.
Drive does seem a bit smoother.
Can not really say about any power gain or anything.

 

run some pre-mix in the fuel tank at a ratio of .5oz per gallon or even 1oz per gallon for the first tank after decarb. helps everything seal up well.

 

Yes, and don't forget to pat your head and rub your tummy before starting each time too, that keeps the rotary gremlins away.

 

The bold part is very important, I don't know why people always forget that piece.

 

My favorite post so far.

I will try the water decarb soon too and post results. My Rex starts barely starts so it should be a good benchmark.

 

Bump due to current discussions on other thread:
https://www.rx8club.com/series-i-tro...ad-cat-242313/

 

Maybe it works so good that nobody else bothers to publish positive results?

Did you try it? Let us know what difference it made, but people seem to mostly overlook that this occurred with a decently running engine. Generally most people wait until they gave an "oh, poop" moment when they come to realize the engine might be toast. In my experience (again) it won't make any or enough difference to matter then.

Further, if it was as simple as just using water don't you think Mazda engineers would be smart enough to suggest that instead? If not, then why? Oh, and be sure to change your oil afterward too if you care about the bearings and other internals.

It would make more sense to me to use the hose from the intake boot to the primary port air bleed than the manifold nipples too.


.

 

Thanks for the input.
I plan on trying it when I can, there is a lot of unfinished business I have to take care of before I'm able.

I have a RTC tester, I plan on doing an oil & filter change along with the other standard maintenance items including new plugs afterwards.

I've seen various methods and suggestions for Mazda cleaner, distilled water, and windshield fluid.
I'm going to decide on a plan and post my method and results in my old thread whenever I do it.

The way things are going, it will likely be in the Spring if my engine doesn't completely fail before then.

 

Water method is cheap and can work when properly done, but if not properly done, prepare for a lot of oil changes.

I still have a can of Seafoam cleaner(the one you spray into the intake) sitting around, and it was long past the return period. I think I may as well just use it at some point.

 

I wonder if one of the reasons more people don't do it is that they simply don't want to put forth the time, effort, and expense on what appears to be a waste of time & money.

Let's assume the original owners who bought new ones for the most part would bring their 8s to the dealer for service during the warranty period.
Not all, but probably most.

Most of those maybe didn't know about, or didn't want to pay the dealer's exorbitant prices for 'Zoom Cleaning' (?) as a maintenance precaution, and maybe it's only recommended to some when they are informed that their compression is failing.
Maybe it helped, maybe it didn't, but Mazda came up with it to combat a known problem.

Fast forward to warranties expiring, the engines are failing at an alarming rate, the problems are becoming widely known, throw in poor MPG, very expensive catalytic converters failing, add in all of the other common little bugaboos we all know about, and the RX8 has become known in a lot of forums as a 'Lemon', perhaps deservedly so.

Then given the declining sales of new 8s, resale values plummeting, it's bad reputation becomes reinforced when it's announced that Mazda will no longer produce the RX8 citing poor sales and the stricter European emission standards that they know they can't reach.

Now more owners who persevere are faced with multiple engine replacements.
I can imagine the frustration of doing it once, but enduring it multiple times and being without your car multiple times for what seems to be a short term fix until the next one blows, I couldn't imagine.

So now, years later, once expensive used 8s can be had for a fraction of the price, people who are not aware of their bad rep, (including me) buy them AS IS and suddenly become aware of their shortcomings.

Most likely many are angry about the issues they're faced with and just get rid of it.
Some buy the now even cheaper 8s and use & abuse them.
When faced with repairs that now are half the value of their raggedy cars, do we think they will go through the trouble of bringing it to the dealer for a pricey procedure that 'might' work?
No, they sell again, or completely give up and junk them.

Now, the owners who are enthusiasts about the RX8 are the ones who do put up with multiple engine replacements and all the other problems that crop up.
They are probably mechanically inclined, have learned how to maintain them the 'right' way, enjoy wrenching & tinkering, doing performance & cosmetic mods, and want to keep them as long as possible.
(Me included)

How many will decide to pay for a compression test at the dealer, do a cleaning, then do another compression test?
We're talking in the neighborhood of $500.

Throw in attrition through total wrecks, salvages, and partouts, and the numbers keep dwindling.
Some of us have now purchased rotary compression testers, and these are probably the likely candidates to do a before and after cleaning test.

So taking all of these things into account, I think it's understandable that we don't have many examples.