trperic

Hello, I am a newbie when it comes to the RX8. I have been working on cars for well over 15 years, but I do understand this is an entirely different animal and none of my past experience will really carry over.

I changed my spark plugs today at 33,000 miles (car is 2009 model). It was running just fine, but I am trying to keep up with all maintenance per the schedule.

I noticed there was a lot of tan colored carbon buildup on the plugs. Hopefully somebody can take a look and tell me if this is normal or not.

Car runs fine, gets 22-23 mpg on highway (60-65 mph), has had oil changes with GTX 5w-20 every 3,000, transmission and rear end fluids changed once, air filter changed twice. Picture will be attached, thanks for taking a look!

Iluvrevs

Thats about how mine looked coming out of my 2010 MT after 20K miles less that amount of carbon. I did have some carbon on my back rotor trailing plug, but no where near as heavy as 2nd most carboned you show. I couldnt tell if I needed new plugs or not, but changed on that interval to be safe.

trperic

Thanks for the reply. I generally drive the car at as low of RPM as I can, but it looks like I may have to change that to keep the engine cleaner.

Ricky SE3P

iTrader: (10)

A red line a day keeps the Stealership away

fyrstormer

There is no point whatsoever to keeping the revs down on this engine. It doesn't save gas, it doesn't make the engine last longer, it doesn't do anything except reduce exhaust noise.

4-cycle piston engines need two crankshaft rotations to finish one combustion cycle per chambers. 4-cycle rotary engines need to three crankshaft rotations to do the same. Rotary engines will always need to rotate 50% faster than piston engines because of their design. The 9000rpm redline on a rotary engine is comparable to a 6000rpm redline on a piston engine; they're not extra bonus RPMs you can use when you want, they're required RPMs for the engine to achieve its specified power output.

olddragger

iTrader: (3)

where do people keep getting that this engine has a 9K rpm redline? It doesn't. Please search.
Recommended redline is approx 8.2 K--to 8.5K max. if you are interested in your engine lasting --that is.
Dont forget you still have an e shaft etc flying around in there. Yes the rotors turn slower but the bearings etc all take a beating from constant high rpms.
Redline a day doesnt do squat for carbon buidup. Sorry.

redline86

iTrader: (7)

^More justification on why I lowered my redline and run a sohn with idemitsu.

wcs

iTrader: (2)

Plugs look normal and ready for a fresh set

+1 with olddragger

ASH8

Plugs are normal...and Denny (OD) is spot on...

As for 'the' Red-line a day mantra, again as OD says, you will never prevent carbon build up in your RX-8, particularly S2's which has no AP available so they remain a rich running engine.

Yes, a few high RPM changes are good for engine each day (use), (won't stop carbon build up) helps to keep spark plugs in a better running condition...also helps to keep SSV, VDI valves in a working order.

Revving engine past tacho red-line will do more engine harm than good (long term).

Ricky SE3P

iTrader: (10)

I shouldve been more clear on my redline comment. ASH8 nailed it with the benefits of "redline" (rpm changes), and both him and OD are right about the carbon.

Bladecutter

That's pretty much exactly how my spark plugs looked when I changed them the previous Sunday with 20,165 miles on them. The very next day I did a nearly 700 mile round trip drive from Denver to Las Vegas, NM and back, and averaged 22.3 mpg at a cruise control steady 78 mph.

Our oil change intervals are the same, though I use Pennzoil instead.
I also have changed the trans and rear diff fluids once, also.

No matter what you do, mileage will be the same.
And as long as your OMP keeps giving the engine oil, the plugs will always look the same, too.

BC.

trperic

I appreciate all the replies, thanks!

atomicode

For comparison - here are mine at 27500

fyrstormer

I get it from my tachometer, which shows a series of red lines past 9000rpm. Forgive me for being obtuse, but I'm pretty sure they wouldn't put the redline on the tach at 9000rpm if it were unreasonably risky to rev that high. As for revving past redline, I'm not sure where that concern came from, I don't recall anyone mentioning it until ASH8 did, but the original comment was "redline once a day" not "hit the emergency ignition cutoff once a day".

I think you're thinking of the yellow-line around 8250rpm, which is when the shift beep sounds. (I have no idea if that's what it's really called, but older cars I've seen actually have a yellow line before the redline, hence my name for it.) The only reason that's there is to give the driver time to react before exceeding the redline at 9000rpm.

Anyway, your response completely ignored the majority of my post and ranted about a single number therein, so...have a nice day.

redline86

iTrader: (7)

you missed OD's point all together. OD is describing the redline at which point engine damage occurs not what shows on your dash.

Directly from Racing Beats website (but what do they know)

"If you intend your race engine to run above 8,500 RPM or if the engine is a non-standard assembly, we recommend balancing the rotating assembly. The rotating assembly includes both rotors, main pulley, front and rear counterweights, and the eccentric shaft. We also recommend balancing the pressure plate and the flywheel on the rotating assembly.
In our experience it is not necessary to re-balance a stock or mildly modified engine operating below 8,500 RPM if the rotating parts were originally intended by Mazda to be used together."

xexok

You missed fyrstormers point altogether. The tac SHOWS a 9k rpm redline, so that is the redline. Sure there may be other suggested rpms to go up to instead but the redline is 9k. This is like arguing that a stop sign is purple. When you hit 9k rpm on the tach you are actually less than that by up to 500 rpm I believe so even if you think you hit 9k you really didn't in most cases. I'm not sure if it is always that inaccurate but I know it can be.

9krpmrx8

iTrader: (46)

It's always off by 500RPM or so. So when noobs think they are hitting VTEC they really are not.

redline86

iTrader: (7)

This thread has become as useless as an oil debate. I understood fyrstormers point perfectly. OD's point was more important. Oh and the red actually starts at 8.5k on my dash.

fyrstormer

I didn't miss his point, I dismissed his point, because it's silly. The car manufacturer, which has tens of thousands of engine warranties to worry about, is not going to print a redline on the tach that is high enough to allow engine damage from occasional use. OD seems to assume they would make such a blatant mistake, which gives me reason to doubt his opinion.

Also, you're using a quote about a race engine to back up an argument about a stock engine. That right there should be a clear sign your comparison is invalid. Race engines get the **** beaten out of them a lot more than stock engines do. Revving to 9000 a few times a week will do nothing significant to my engine, because I normally keep it below 6000, and I cruise around 3000. A race engine cruises much higher, because the car is going faster and accelerating harder.

Redline starts at 9000 on my tach. Yellow-line starts at 8500. When you hit yellow-line, that's your cue to hurry up and shift. It does not mean "abandon all hope, ye who enter here".

viprez586

iTrader: (5)

Just give up and chuckle when he's in for engine replacement.

Furthermore shifting that high is NOT good for our transmissions at all. They don't like 9K shifts, many people know this the hard way.

Anyway. OP those plugs look pretty standard for 30k. I do mine every 20 or so. If you want to save money, buy the spark plug cleaner from harbor freight. They clean up great!
I'll post pics when I get a chance.

Flooded plugs.


Cleaned up.


Carboned plugs, 25k


Cleaned up.

wcs

iTrader: (2)

Cleaned up how?

redline86

iTrader: (7)

You're right, in the words of Ron White "you can't fix stupid"

He must have a series II anyways, there is no yellow zone on my dash, I have a faded red zone that starts at 8.5k

rickeo

iTrader: (1)

I used the fact that he said "spark plug cleaner from harbor freight" and used my google-fu which led me to this..

Pneumatic Spark Plug Cleaner

wcs

iTrader: (2)

oh I missed that,
Was reading/posting from my phone.

Thanks for the linky

edit:
Hmmm interesting. Can you google the forum for me too please too see what kind of success people have had with this?
I'm not convinced ... I always use fresh plugs

I thought I read somewhere that the plugs were only coated in iridium and such a procedure would remove that.

I'm being lazy however and not doing any checking first

jasonrxeight

I would check the gap after cleaning see if they are still in spec.

also on a side note, I notices some MIAC sound when I floor it at lower rpm usually around 3-4. it happens only when I floor it. maybe time for new plugs? I have 23k on the clock. no CEL or flashing CEL.