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Mazda RX-8 Problems and Solutions



  • trispectrispec Posts: 305
    Have you noticed that the AC light seems to switch itself back on. I'm constantly having to turn the AC off. As for the fuel usage with AC off, it appears in city driving, AC costs at least 1-2MPG.
  • pathstar1pathstar1 Posts: 1,015
    Note that while you may notice a drop in fuel efficiency in the city, on the highway use of the A/C with windows closed will be more fuel efficient. Also, if you do not use "recirc", you are getting "fresh air".

    Intake air heating has been with the rotary from day one. We think (it's been discussed for years on end) it's caused by the engine being mounted so far back in the engine compartment. This heats the firewall/dash/console, above which is the air ducting.
  • I've posted this on several other RX8 boards.
    Has anyone experienced a loss of power at highway speeds in 6th gear while driving at 65-75 mph?
    I've noticed this on several occasions while on cruise and starting up a gentle incline.
    The speeds drops off the set speed and setting on the accelerator has no effect. Dropping down a gear stabilizes the speed but nothing more.
    I noticed a thread on this on the RX8 club and some thought it was related to a stuck shutter valve. Any one here have a similar problem?
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  • ukjimukjim Posts: 63
    Note that while you may notice a drop in fuel efficiency in the city, on the highway use of the A/C with windows closed will be more fuel efficient.

    Do you mean that it will be more efficient because the mechanical load on the engine of the A/C running has less effect than the aerodynamic drag associated with driving with the windows open? An interesting hypothesis, has this been documented? How far open does the window have to be open before it becomes less efficient?

    Or just that hwy driving will not be as inefficient as driving in the city? A fairly obvious conclusion irrespective of A/C use.

    Certainly any extra load on the engine cannot result in better gas mileage.
  • pathstar1pathstar1 Posts: 1,015
    It's been documented for several vehicles. I haven't tested the RX-8, but my Pathfinder definitly has less drag with the windows up. I tested it after reading in the owners manual that better mileage would result from use of the A/C instead of opening the windows. Now when decending mountain passes I open the windows to help hold the speed down. It works well, even though it's a bit noisy.

    It will not work in the city because the speeds aren't high enough for air drag to be much of a factor.
  • trispectrispec Posts: 305
    So my Group 2 2005 RX-8 AT has had a little noise since day one, which sort sounds like preignition only much software. It noise seems to exist at lowish RPMs.

    After months of searching online and after discussions with my dealer, there does appear to be some official confirmation of the sound by other owners of the RX-8 AT, but there does not appears to be any official response from Mazda.

    Some dealers say it's very bad and replacing the engine is the only fix. Some dealers says it's a bad fuel pump, but there are no fuel pumps available currently to replace it. Some dealers says it's just bad gas. Some dealers says it's normal, but they don't say why.

    My engine get 24.9 MPG on the highway and 14 MPG to 18 MPG otherwise. I think that millage is fantastic! I've never had a start problem nor a fading power problem at high RPM. And my RX-8 never produces the sound while revving the rotors in neutral.

    So does an automatic transmission have a normal little rattle sound at low RPMs? Is it some kind of normal slippage until it's spun up over 4K?
  • trispectrispec Posts: 305
    There's 8K on my RX-8 AT. Like to get this settled before 15K.

    What's so bad about a little bit of preignition?

    I can remember every car made had preignition knock from 1970's through much of the 1980's. The engine designs and unleaded gas additives got worked out. In 1979 I worked for a nutty guy who paid $700 to some guy to rip out the Cat converter just so he could run leaded (no knock) gas.
  • pathstar1pathstar1 Posts: 1,015
    Sounds like motor mounts to me. They are fluid filled and seem to be easy to damage during manufacture, as there were quite a few replaced. Have a dealer check them.
  • trispectrispec Posts: 305
    It's a soft sound, not at all like a metal on metal. Wouldn't a lot of vibration occur if a mount was bad too?

    I'll have them look on next oil change. Thanks.
  • trispectrispec Posts: 305
    Well, after three days of carefully listening to my little knocking noise I'm more and more leaning back towards minor preignition. Here's are the symptoms:

    On cold starts: 1) Tiny bit of knocking can be detected even with 2-3K revving while still in neutral/park. 2) On shifting to reverse, immediately a little knocking noise is there continuously. 3) Driving out of my drive way at home or the parking garage in 1st gear only, the knocking noise is there going up the hills or garage ramps, but the noise goes away going down hill or down ramps as I take my foot off the gas to coast down the incline. 4) On flat surfaces the noise comes and goes, but mostly seems loudest at low RPM acceleration.

    After warmed up: 1) The noise seems to lessen considerably, and is clearly gone for high revving or constant cruise speed driving. 2) Comes back very slightly once I return to low speed, low RPM driving in traffic and in my neighborhood. 3) Is not present when stopped and in forward or reverse gears. 4) Is not present when revving in neutral.
  • Are you using high octane gas? It is not required for the RX-8...but it is recommended.
  • trispectrispec Posts: 305
    Nothing but Shell Super Premium 93 for my baby. Of course, I buy it from the same place mostly. Maybe I should switch vendors. I buy from a place that probably does more volume than any place around Boston. Lowest prices. There are twelve pumps and there are always lines.

    Pathstar said if there was significant preignition the sensors would cut back on power in a serious way and the check engine light would flash. I've never experienced any loss of power nor have I ever seen the check engine light. Maybe the amount of preignition is not triggering the sensor? Is a little preignition really bad? Will even the slightest preignition slowly damage my engine in some way?

    Back in the 70's and 80's every car on the road had preignition knock because of the unleaded gas and engine design issues.
  • They said I had a defective engine after 3,000 miles. It has been in shop now for 10 days. They have to replace the engine. They will not give me a new vehicle, they said first they will give me a remanufactured engine and I raised hell. They then said they will get me a new engine even though on my service report it will say remanufactured because the serial numbers will not match up. They said the engine is in but other parts will have to come from Japan. I have a had an RX-7, GLC, 626 and 929 but being treated like this, I will probably never own another Mazda. Any legal help would be greatly appreciated.
  • trispectrispec Posts: 305
    What were the symptoms? Sorry. Your State's Lemon law may help, but usually, the all the lemon laws do is give the dealers plenty of tries to fix the same problem before the declaration of "lemon" can legally be applied.
  • trispectrispec Posts: 305
    Leaving the windows down on these weird warm winter days here in Boston to listen to the little noise. Here's a new wrinkle: with windows down, to catch the sound bouncing of walls and Jersey barriers out side, the sound is more of a gurgling sound than a crackling sound.

    Windows up you can't hear the true texture because it's muffled.
  • I think I remember reading some other posts concerning what seems to be excessive fogging of windshield and rear window. I noticed this when I first bought my RX-8. And I found a simple solution:

    Give the inside of the windows a good cleaning! (I used Windex).

    I don't know what it is about new cars...but my mother's new Cadillac had the same problem. Perhaps there is some film that accumulates during production; but with both cars, a good cleaning of the glass corrected the problem.

    WHEW...I was worried that is was a design flaw with the car!

    Not to isn't.

  • pathstar1pathstar1 Posts: 1,015
    All cars get a constant coating on the inside of the windows from "outgassing" of the plastics used inside. When I say "constant", I mean it constantly builds up. The windows need to be cleaned at least once every few months.

    Misting can also be reduced by not using "recirc" on the air system. If you select "demist" (not the rear window heater) it will "power reduce" misting, by using the A/C to remove moisture from the interior air.
  • I thought you were not supposed to clean the back window with any cleaning agents like windex?
  • Where did you hear that? And only the back window??
  • pathstar1pathstar1 Posts: 1,015
    Agressive cleaners shouldn't be used on the rear window as they may chemically attack the heater tracks. Spray-on foaming cleaners may be agressive - the one I have (for the outside of the windshield) contains lots of sodium hydroxide. I don't think Windex is agressive, but if you're worried mix your own. The "standard" recipe for glass cleaner is 50% isopropyl alchohol and 50% distilled water, with a drop of dish detergent in it. Mix up a liter or so and use as required. Do not use scrubbers. Wipe in the direction of the heater tracks. Be careful not to snag the connections at either side.
  • in the owner's manual :)
  • Does anyone else encounter vibration when your in second gear. When im reving around 5,000 in second the vibration is much greater then any other gear.


  • trispectrispec Posts: 305
    While turning or going straight or both? I was going to guess it's the LSD, but then mine vibrates worse at lower RPMs.
  • pathstar1pathstar1 Posts: 1,015
    5000 RPM is just above port transition. We know from measurements the air/fuel ratio is disturbed there (it falls lean). It may be that second gear (being such a low ratio) magnifies the engine response to a disturbed air/fuel ratio resulting in noticabley higher vibration.

    With so many gear/RPM choises just use another. Mazda may fix that with "yet another" reprogram. Is your car up to date with its' PCM flash? Some of the flashes made the port transitions worse, some made them better.
  • This is my fourth update post with almost 3 years (Bought July of 2003)and 27000 miles on a GT model with automatic transmission. Car is running well with the bugs worked out of it. A/C issue fixed by installation of a new A/C unit. I recently moved from NJ to Florida and A/C still works well. No problems with auto trans or oil pressure light others have mentioned in their posts. The original Bridgestone tires made it to 27000 miles-very noisey and lots of vibration-don't get the Bridgestones. Just swithced to Avon Tech M550 M & S tires from Tirerack. Much quieter tire, though not as sharp handling in corners but, overall a big ride and noise reduction improvment. Will have to see how they wear over time. Have learned to let car warm up before shutting it off or it will flood-as most posts mention. Getting up to 22-24 mpg on highway. Only about 16-18 mpg around town. Lots of brake dust on the front rims, hard to keep clean. I enjoy the car alot more now that the early bugs have been worked out.
  • trispectrispec Posts: 305
    Fantastic. My 2005 RX-8 AT with 9000 miles had all the bug fixes at the factory and I've been very happy.

    I switched to the Avon Tech after only 4000 miles on the Bridgestones. Love'm to for the quite smooth ride. On good road surfaces there is absolutely no noise other that the wind.

    Question: Does your RX-AT have the little engine knock or marbles noise below 3000 RPM? I use 93 octane Shell Super Premium and there is still the occasional noise. No check engine light or loss of power has ever occurred.
  • as i recall, staright line only.


  • Car is : late 04 6 M GT ..FUlly flashed.

    So you figure there may be another flash in the works.

  • rorrrorr Posts: 3,630

    Limited Slip Differential
  • I have an 04 6-speed. In the last couple of weeks, I have been having problems with heat and A/C. I get hot air both on vent and with the A/C on (outside and re-circ). I hear a buzz in the AM radio when lights are on. And about three weeks ago the main dashboard display went haywire (flashing all kinds of weird numbers/letters, etc) until I stopped and re-started. Hasn't happened since. Dealer says may have grounding problem, but won't be able to see it until later this week.
This discussion has been closed.