Bladecutter

Actually, I was referring to Monchie, as he seems to do that in all the threads I've seen him in. I didn't mean for you to feel like I was taking a shot at you.

BC.

Bladecutter

I can do that.

BC.

Bladecutter

Actually, I posted quite clearly the bit of information I needed cleared up.
I received the answer that the bulk of the carbon build up occurs outside of the actual combustion chamber, which decreases the exhaust efficiency of the engine, which prevents it from breathing properly.

None of this information came from you.
You don't seem to actually want to participate in a dialog that might give the OP some ideas on how to either get his engine up and running again, or get Mazda to replace it on their dime.

And in your own words, this is your typical response to people who ask questions.
Good for you on that. I'll keep that in mind.

I can understand your posting style had I come in and asked questions like the following:

What type of oil should I use? Is synthetic okay?
Why does my owners manual say I can't use either synthetic or semi-synthetic oil (mine actually does say that)?
How can I get 30 mpg out of my RX-8?
How can I get 312 hp out of my RX-8?
What size rims can I install on my RX-8 without scraping the upper shock mount?
How can I make the suicide doors into Lambo style doors, because that would be sooooooo hotz?

Those type of questions, I can understand your reaction to, but that's not what I asked, nor will I ever ask questions like those, on this, or any other forum I ever take an interest in.

As for searching for the answers to my questions, they didn't turn up the answer that I was provided in this thread. I did pull up plenty of pictures of fugly looking rotors on torn down engines, but no pictures of the exhaust ports being decreased by carbon deposits.

Hence the reason why I asked.

Yes, everyone is a newbie sometime, but if a newbie isn't allowed to ask interesting and deeply technical questions, why let newbies join at all?

Search doesn't always come up with the right answer.

To 1.3_LittersOfFurry,

I'm sorry I sidetracked your thread a bit, asking for clarification of how carbon deposits can increase or decrease the compression in your engine. Knowing what I know now, I would bet that a carbon clean out of your engine would decrease the compression readings much further than they currently are due to the carbon is currently increasing the back pressure read on the compression test.

Once the carbon is gone, you will probably drop down lower, and its free engine time for you. Might be worth having them try it, if you can't do it on your own. I read through the TSB procedure, and its not too bad, just has a long list of steps.

BC.

monchie

You called? What is the problem? Trying to blame it on someone like me?

Anyways, thanks for letting me know about it

SayNoToPistons

iTrader: (8)

monchie, just shut the **** up. Oh wait, you incapable of doing that.

1.3_LittersOfFurry

iTrader: (4)

Actually the engine wad as clean as possible, I had already seafoamed twice in under 2000 miles, last one being one week prior to the compression test. And once I was at the dealer they performed Mazda's own decarb procedures (zoom-zoom treatment) before doing the compression test. But now that I have a scanner that does live feed I feel confidant I can perform my own accurate compression test when ever I please.

-Shawn

monchie

You got it. Please stay tune for more and more and more and more and more of me, that's it for now...

laythor

I've seen a tech at my local mazda dealer just squirting zoom-zoom cleaner into the TB while another tech kept enough throttle to keep the engine running.

1.3_LittersOfFurry

iTrader: (4)

Wouldn't that be a good thing? lol
The less they clean, the lower the number, better the chance to fail?

It looked like they performed it by the books when I went, it took about 3.5 hours from when I rolled in to when I left.
I got:
-Diagnosis
-Zoom-Zoom cleaner
-Compression test

Sounds about right to me. I watched the whole time, The car was in the first bay behind the service counter. All I had to do was stand up and I could see the car's engine bay completely and they let me in a few times as well.

When I did my own decarb treatment with seafoam, I followed the steps in the DIY section by nycgps.

The only thing that bothered me was the mechanic saying they were really good numbers and people on here said they were about or right below average. I'm more inclined to trust the honest opinions on here than the mechanics even though he was extremely nice, and assured me if it failed there would be no problem getting the engine replaced under warranty. I don't know if they are considered a big enough dealer to make that kind of call on their own without contacting Mazda (it was a Lincoln/Mazda Dealership), or that the car had tons of service done with receipts.

But I could have copied the numbers down wrong like I stated before, And since my scanner is telling me I only have 180 cranking rpms I'm really starting to think so. Which lead me to bring back this thread to see what people opinions were on the method I was going to use to perform my own compression test. Which no one answered

-Shawn

Bladecutter

Well, from what I see, you have a couple of choices:

1- You could simply take your car to another Mazda dealer, tell them you have a loss of power at higher speeds, and have them do a compression test, and if they get the numbers your current shop got, they might actually be willing to replace the engine unlike your current shop.

2- To get the higher rpms if you decide to do your own compression test, you can hook up another battery to yours to increase the available cranking amps with jumper cables. That's most likely what the dealer did to get the higher rpms from your starter.

I think the big issue you would have is not being able to tell which section of the rotor gives you which compression readings.

Personally, if it were my car, and there was another Mazda dealer within 100 miles, I would take it to them, and try going that route. If they say no, then simply drive the car until early September, without doing anymore pre-mix, and have it tested again then. it might then be low enough to force them to replace it.

Also, if you haven't already, replace those 2 coils now, because you will have to pay more if the dealer has to replace them at engine replacement time. You will have an even better running car than you already do.

BC.

RotaryResurrection

iTrader: (3)

Carbon buildup decreases compression in a rotary for a simple reason. There are seal slots cut into the rotor, with seals that fit down into these slots, similar to the way that piston rings fit into a piston ring groove.

Under each seal is a thin spring that pushes it out. This collection of seals and springs maintain compression, by forming a collective "ring".

When you let the engine carbon up, the carbon gets in the seal grooves and underneath the seals/springs. This makes the seals tend to stick in place, and prevents the springs from working as well. Now you get lowered compression due to this fact.

You are technically correct in that carbon buildup on the face of a piston (or rotor) will increase dynamic compression. It's the fact that carbon makes the seals stick that makes carbon the enemy of a rotary.