brillo

I wanted this to have a little move visibility since the engine failure thread my not get everyones attention.

It appears that the AT cars are having engines carbon lock due to some owners not driving the cars hard enough, such as people who spend most of their time cruising at low RPM's such as highway driving.

All AT owners need to rev to at least 6,000RPM once every other day, you don't need to drive it like you stole it, just switch over to manumatic mode and hold second gear into the upper rev range. This is very important for engine maintenance.

As we learn more about the issue we will post it here. Good news is the fix is rather simple and fun.

bxb40

I agree. At 17,000 miles, the dealer changed the spark plugs (as per a hard start bulletin - new battery and re-designed spark plugs) and the old ones were really clean.
I use manumatic at least once a day/drive, and after the car is fully warmed-up, I take it to redline (in second gear, cause in third you have to go to 120mph).
I'm also using premix (motorcycle oil in gasoline) to make it for a weak OMP the AT supposely has.

09Factor

Thanks 4 the update brillo. I pulled the plugs out @ 8, 12, 16 and 20 (today) K. miles.
The weren't dirty just a little brown on the ends if I remeber reading thats ok. . however I did notice when I did drive like a grandma for 300 mi and then redlined it the tipis and rear bumper/trunk had nice small black specks all over. looks like the carbon builds up fast.

Most trips have a minium of 2 redlines.

DreRX8

I drive my A/T haaaarrddd, I stay at redline--trust me--I don't think I have any carbon build up. :p

army_rx8

^hehehe

brillo

keeping the engine clean doesn't mean you have to redline, 6,000 or so should do fine. Red-lining is fun, but to strike a balance between economy and performance, the general consensus is that 6K is good enough.

Ajax

stickied.

Intrigue 8

thanx for the info!

Millah

I have a question then. I read elsewhere on these forums not to exceed 4000 rpm for the first 1000 miles. I'm at 250 right now. Which is it? Should I exceed 4000 rpm and hit the 6k every other day, or should I wait until I hit 1000 miles before doing this?


Thanks.

nzarnow

Wait till you reach 1000 miles before hitting the upper revs. You do not have any carbon build up or any other junk in your engine yet. However, I really doubt that you can hurt the engine from revving it....just all the other stuffed attached to it will start falling off. Make sure you break the CAR in. It is not just the engine. Hit 1000 miles and then start driving the tach north every once in a while.

Foamy

Just read this about clearing carbon by 6000 RPM per day.
Sounds logical, but does it have Mazda approval or support. If so why don't they send us notifications about it??

My poor old car must be choking by now, I drive just 0.8 miles each way to work every day, had the car exactly 12 months and done only 5,500 miles.
About once a month I drive it hard for about 50 miles because I got to get the fun from it.
I have had no problems, but milage at 10 - 14 MPG is rather dissapointing.
Just got the "S" file for engine computer - not noticed any difference so far, any one what this "S" flash version is supposed to do?

therm8

10-14 is poor but somewhat expected for such short trips, the car chugs the gas during warmup. I'd recommend the scenic route every now and then for some 6k+ lovin'

Foamy

Yep, living in the North East with a car that needs warming up for five minutes before driving it less than one mile 4 times a day is really asking for poor milage.
Even so I really love this car.

DOMINION

So when I first got my 8 and was just driving in low RPM's for the brake in. Then one day I let her rip and poof! a big ball of black smoke was behind me. I went to my Mazda dealer and the teck said it was bad Cats and they need to be replaced. Could they have been damaged by the low rev brake in and all that carb build up?... Hmmmmmm.

ferrocene

I get single digit gas mileage (as in, 8-9 MPG). I drive .5 miles to work. The only reason I don't walk is because sometimes I need to drive around on the job. But getting >10MPG really sucks. At that rate I'm afraid reving it to 6k will only make it worse!

But I do it anyways.

red8gt

so how long should i be holding it at 6k... i drive my car fairly hard, always in M and i usally hit the 4-5k mark in 1st and 5-6 in 2nd before changing gears... is this good enough, or should i be letting it stay at that mark for a bit

StealthTL

iTrader: (1)

Anyone running pre-mixed 2-stroke oil should be sure to get the good stuff. Cheap 2-stroke will only deposit more carbon, as it does in a 2-stroke engine.

The type to find is rated ISO EG-D. The "D" rating is the highest spec, and the tests are very demanding, as to carbon deposits and smoke. At 200:1 or above pre-mix levels it is absolutely smokeless and deposit free.

S

therm8

take it to redline every couple of outings (I do it every outing at least once), and that should be sufficient.

EyeBall Fixer...(o)(x)

Yeah, I hear ya brother!
I drive 2 miles to work and my "best" MPG is 11 in an 04 AT.
...and I thought I was the only one getting this kind of (or lack of) mileage.

robertsteven

I guess I'm lucky, my mileage has been around 20-21 mpg with the automatic. Didn't know about runnin in at 6k+, but how can you not. That's the reason we have an RX8... for high revin' fun, although the redline beeeeeep is annoying sometimes.

Any reason the AT has a lower redline then the manual? My guess is the 4 speed tranny can't handle the HP, so they put less intake ports in the motor and limited the RPM to detune it. I think the motor for the AT & MT are the same, so reaching redline for the AT stills leaves over lots of Revs before you damage the engine.

The '06 with the 6 speed AT has more ponies. Probably much better off the line. 4 speeds is just not enough. 1st is too high, and gap between gears is too much. I didn't notice if the redline was increased.

SlayerRX8

To the best of my knowledge, the limiting factor for the redline was the torque converter....9k would be a hell of a lot of rpm for it to work properly.

Zero_Rotary

I find it a bit contradicting...i thought if you always redline ...engine & tranny life span would be reduced...i can understand why we need to rev it hard to blow out the carbon built...just the contradiction is confusing

dillsrotary

the engine was built to redline, the parts constructing it are not considered "wear" out parts like the tires, clutch, etc. redlining or driving over 6000 rpm will hardly effect the engines lifespan.

fizzer

Rotaries actually suffer less incremental wear from high engine speeds when compared to a piston engine. The lack of reciprocating motion and lack of a valvetrain means that the stress levels at high RPMs aren't that bad. It one of the reasons I got the RX-8, guilt-free redlining

llzjayarzll

yea i hear you all. ive been getting significantly low mpg since i installed my greddy sp2 on my at 04 =(

any solutions?