Howdy, Stranger!

It looks like you're new here. If you want to get involved, click one of these buttons!

Mazda RX-8 Problems and Solutions



  • I don't have an RX-8, but my friend and I both expierenced this problem at the same exact time. My car has a temperature guage and his just has a warning light. I would notice then when my car started up, if I just let it sit, the temperature would go up real fast. I'd usually have the heater going (uses coolant as well). Same thing would happen when I'd sit at stop lights for several minutes. When I'd start moving it'd be fine. What I found out was that I was very low on coolant, but when I was moving there was so much cold air coming into the engine it didn't matter. It ended up being a small leak in one of the hoses that connects my engine to the radiator. Those coolant warning lights don't measure mass of coolant -- they're generally just warning lights for when the temperature of the engine gets too hot.

    I hear the RX-8's are sorta cumbersome to work on under the hood, but it shouldn't be too hard to find the radiator, pop the cap, and put in some coolant. If you have to put in a lot, you got some problems. You can also check the overflow tank too. Do all this when the car is cold and hasn't been driven for several hours at least.
  • trispectrispec Posts: 305
    Looks like a bungi cord caught my left front wheel rim and got slung up on top of the fender. I was going 70mph in the left lane and heard a loud bang. It put quarter sized dent and two scratches that fit the shape of the metal spring end of a bungi cord. The dent is right on top next to the nice crease on the fender.

    I bought the dent kit, "Ding King" product. Looks pretty logical how it works. Has anyone used this product?
  • moadhmoadh Posts: 15
    Just wanted to know if anybody else is facing this problem, i know that the rx8 is known for very high fuel consumption (smth like 10mpg) but with my rx8 its just crazy. on a full tank, i would consider it an achievment if i can get upto 300KM of mileage! is that normal or otherwise? if anyone has any tips on lowering the consumption please let me know, fuel prices are just getting higher and higher (even though i live in UAE, where we have 1001 oil fields!)
  • trispectrispec Posts: 305
    My RX-8 AT get's 14-16mpg in Boston's heavy traffic. If I drove with the RPM above 4000 constantly, like the RX-8 wants to drive, she would probably only give 10-11mpg. She gets 18mpg in country rural driving. She gets 22-23mpg on pure highway, but I averaged 84mph on my last five state trip up and down the eastern USA.

    Keeping RPMs between 2500-3800 gives me the results above. But I do let her run free when I can. With the RX-AT it's really easy to use the paddle shifters under full power to hold back on the RPMs. Of course I'm definitely giving up the higher end house power boost. But one can't really drive with the higher RPMs in Boston traffic.
  • moadhmoadh Posts: 15
    Hehehe if you thought Boston traffic was bad, you gotta see Dubai's.. My brother lived in boston for quite a few years, i can recall all the gridlocks; especially in that long-[non-permissible content removed] tunnell, forgot what it was called! hehehe but in some spots, in Dubai, traffic gets even worse than that. PLUS, i drive a MT! oh well, i guess its the price we hafta pay for having such a sweet ride ;)
  • ukjimukjim Posts: 63
    I havent seen too many postings about this issue so I am wondering if it is somehow specific to my car, an'04 MT with 12K miles on it.
    On a 60F foggy LA evening I am stuck in slow moving traffic and within about 15 minutes the air coming out of the vents is about 75+F (Mode is fresh, not recirc), this coupled with the transmission tunnel temp gets the cabin to uncomfortable temps really quickly. I have a choice, open window and be deafened by traffic noise or put A/C on and get even worse mileage and power loss. I cant wait for summer! Has anyone else experienced heating of the fresh air vent air?
  • trispectrispec Posts: 305
    I test drove an early Group 1 2005 RX-8 AT which appeared to have the same issue. I was worried enough about it to jump into the back seat to see what the temps were like for the passengers. It was uncomfortable if the car was sitting and idling. I had read complaints about the poor AC of 2004 and early 2005 RX-8s. I however bought a Group 2 2005, which cools like a champ. In fact I find the AC in my Group2 RX-8 works so well, that I'm turning down the cooling more often than not

    I think the PCMs in the latest flash updates keeps the AC on when it's idling constantly.
  • ukjimukjim Posts: 63
    Thanks for the feedback trispec, I guess my concern is that with the ambient air being only 60F, or less, I shouldn't need to use A/C.
    My new job requires commuting in traffic where I will sit for upto an hour in stop and go traffic. I can live with the MT, but not roasting at the same time. I am aware of the weak A/C but didn't figure on the need to use it in such low ambient temperatures. That the outside air is being heated in excess of 15F in such a short distance, suggests it is being pulled from very close to the engine, not a happy proposition in LA in the summer!
  • moadhmoadh Posts: 15
    Surprisingly, i have a 2004 MT RX-8 (and i live on the hottest spot on earth, where tempratures go as high as 48C) but the AC in my car is absolutely outstanding.. in fact, even under the sun i get chilly inside!
  • trispectrispec Posts: 305
    I've heard about the tunnel heat factor, but haven't experienced anything but some minor warmth to the touch. There was something about the MT tranny directly heating up stick shift area simply due to the direct connection to the engine area. The heating would crack a seal or something. Pathstar sent around the service recall PDF I believe, at least I remember seeing pictures of the stick shift in the service recall PDF point to the problem. PathStar should be the one chiming in here I think.

    As for my Group 2 2005 RX-8 AT sports package, I can't complain as there no heat problem at all after 7500 miles. We just did a 2000 trip down south and I can tell you I has turning the heat up via AC on the 60F days. Of course, there's not much idling in traffic in the mountains of western NC.
  • ukjimukjim Posts: 63
    I hate to be redundant on this but my whole point is that with low ambient air temperatures <60F (<15C), the fresh air is coming into the car at >75F (>24C). I know I will need A/C in the summer but why do I need it in the winter? I am sitting idling in stop & go traffic for an hour, is it normal to have the outside air heated even with the fan on the highest setting? Do I have an obstruction, is the ducting incorrectly connected?
    When moving at speed it is not an issue.
  • trispectrispec Posts: 305
    Ugh, I can be very thick at times sorry. I run the AC constantly even in the winter. I like the dry air and need AC to keep windows defogged. I don't think I've ever turned off the AC since I brought my RX-8 home. I'll do a bit of testing with AC off, but I know, because humidity is general constantly a factor here on the east coast, AC might as well be hard wired in the "On" position.
  • ukjimukjim Posts: 63
    Thanks trispec, I appreciate any help on this, given that the A/C is weak in my car (it has been in for service but to no avail)I cant imagine what summer is going be like.
  • trispectrispec Posts: 305
    Well I turned off the AC. External temp was 33F. Air coming into the car however was roughly 50F with the temp dialed to max cool. If the temp dial is moved to the middle of the cool range, four clicks roughly, the air coming into the car is warm.

    Wondering if it's built this way so that the AC evaporator will constantly have hot air to defrosting it. Years ago I drove a VW Sirroco that would blow a fog during summer. The VW dealer said that there was always hot air passing through the AC evaporator in order to prevent freeze ups. They said the fog was a sign the design was working to melt ice build up in the system.

    Sorry about the story. Middle age man disease.
  • ukjimukjim Posts: 63
    That's OK, I suffer from the same disease! I think I have found the problem but would appreciate someone elses experience, especially if they are familiar with the fresh air ducting. With an hour or so to waste I decided to play with all the permutations and combinations of temp and mode.
    With temp knob at full cold, if the mode is face & feet, or face only, the air is warm, if I select feet only or feet and screen, the air is cold. So, my thought is that if the temp knob isn't completely turning off the flow of coolant to the heater core, and in the first two modes air is directed over the heater core, the air would be warm. It doesn't explain however why when in the feet & feet/screen mode I can still heat the air. Does any of this make sense? I really dont want the dealer pulling the dash apart to research this because I will just end up with a bunch of squeeks afterwards. Thanks
  • ukjimukjim Posts: 63
    I just reread your posting and should have addressed this in my first reply, it appears that you have a similar experience; with full cold selected the ambient air was heated anyway, by about 17 F. Compared to 33 deg, 50deg is warm! Do you remember what the mode setting was?
  • modockmodock Posts: 55
    Just a thought. I don't have a 8 but have a 3 and experience the same thing(warm air set on cold not the warm on top cold on bottom) I think it is because there is not enough insulation between the ducts and the engine. This could also explain why you get warm air through the top vents and cold at the bottom. The vents at the bottom do not (my guess) get close enough to the engine to warm the air but the top ones do. Did you try it with the fan on high. If my guess is correct the air on high will be cooler than the air on low since it spends less time in the ducts. This may not be immediate so give it a few minutes.

    I find that it is much more efficient to crack a window when it is warm in the car and cool outside than it is to turn the vent on cold. I would need to turn the AC on to get the temp through the vent as cool as the outside air.

    Let me know if my assessment meets your experience.

  • trispectrispec Posts: 305
    For the testing I described above I used the "Face/Feet" mode.

    This time of year I almost always have the "Defrost/Feet" mode selected so that I can control the fog levels on the windows and warm my feet. For this reason, I never really noticed the air temps that you were describing.

    Theory: I've got to think the AC evaporator and the preheated external air are tied together as a unit much like a modern defrosting Refrigerator. I also think that non-AC routed air and dry cool air are linked. The evidence I have for the AC/preheated air linkage goes like this.

    1) The AC evaporator collects humidity from the air at temps above 32F. I normally observe a blast of humid air that would fog my windows on starting up in the mornings. The AC would clear the screen shortly, but it was a pain to wait until I could see again.

    2) Since doing your test of leaving the AC off all the time, little to no humid air is getting trapped in the AC evaporator. The last few mornings, there has been no window fogging even though it's been raining.

    On the later link of non-AC routed air and the non-preheated air the evidence comes from this.

    1) When a mode setting contains "Feet", the air blowing from the feet is cooler than "Face" or "Defrost" air without AC running and hotter than "Face" or "Defrost" with AC running depending on the temp setting dial. At least it felt so this evening driving in Boston traffic with an unusaully warm 45F external temp.

    2) Air that would NOT normally want or need humidity removed or cooling added isn't routed through the AC evaporator so it isn't preheated. I noticed the "Feet" blower was much cooler just as you did and the "Defrost" switch caused the same cooler air to blast above.

    The manual describes using the "Defrost/Feet" setting to de-humidify the air to the windows in order to clear fogging. And I definitely see the de-fogging of the windows happen when I turn on the "Defrost/Feet" setting with the AC running.

    Reading the Climate Control section of the manual does not clarify anything else though. I'm still confused about the "Defrost" switch, but it seems to only override the mode settings by design.

    Oh well, now that everything is clear as mud at least I'm not running my AC as much and the morning window fogging seems much better.
  • trispectrispec Posts: 305
    Hitting the published RX-8 numbers is basically just an exercise in restraint. My RX-8 AT with 7500 miles just hit 24.9 MPG. To accomplish this I did the following:

    1) I used full AT only, no paddle shifting, over a little 207 mile trip from Boston to Cape Cod National Seashore via Route 3 to 3A through Plymouth, up 6A, then back on 6 and 3.

    2) Through the little towns on the cape the speed was 20-40 MPH slow off season traffic.

    3) On the highway I never exceeded 65MPH and tried to stay close to the posted 50-60MPH speed limits.

    4) There was no punching take offs and RPMs stayed under 3000 over the whole trip.

    One interesting side effect of driving the speed limit is that you can always use the cruise control because no one else stays in front of you as all other drivers are exceeding the speed limit by 10 or more MPH.
  • ukjimukjim Posts: 63
    I think you are right (I think!).
    With the engine idling and the window open, I could hear what I assume to be the A/C compressor clicking on and the revs drop, when selecting feet/windshield and feet only. It would switch off when selecting feet/face or face only. Interestingly, the A/C light light does not come on on the mode switch.
    Bottom line, I have to run on feet/face when not wanting to run the A/C but want fresh ambient air. This is to my mind a major snafu, at night I want fresh air on my face, if I do that I get warm air that is either heated due to the air being sucked in from right over the engine or, it is being preheated by the heater core. So...I have to run the A/C all the time, not fuel efficient, and it has a noticeable effect on performance.
This discussion has been closed.