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Hey guys. So I THINK I'm having transmission issues. My car is a 2012 JDM AT with around 4000 miles. Let me fill you guys in.
I took the car out yesterday to do run errands. Was crawling in traffic for at least 5 hours. I live in a tropical island. Summer year-round. Insane traffic. Ambient temp was around 95-98F. So, I noticed that the footrest area was getting hot. A little too hot! Definitely more than what I'm used to. The cupholder area was normal. It was mildly warm. The CAT temps were normal too. Around 1100F when idling (CAT is gutted). I then noticed that the car's AC wasn't cool enough while idling. It is still cool, but not ice cold like it used to be. It was warm enough for me to start sweating a bit. Once I start moving it cools nicely. I know this points to a fan issue, but both fans work fine and I'm not noticing any increase in coolant temps. Car still hits 220F in 95F weather. It's been doing that since I got the car lol. No difference there.
Now here's where things get weird. On my way home, I was in a huge traffic jam. Cars were barely moving. Outside temp was showing 100F. I had the AC on low. Coolant temps were around 212-215F. I was stuck here for over an hour. As the cars finally started to move, I got a little excited and floored it. What happened was, the revs went up to 2000rpm, and car moved forward slowly, and then the revs dropped to 1500rpm and then the car pulled like it normally would. It's like I went over an invisible speed hump. After I went over the "hump", the car pulled normally. I tried it a couple of times and I was able to replicate it. I know that when automatic transmissions overheat, you can't shift into manual. I tried it. I went into manual no prob. But the gear shifts were kind of jerky. Not a whole lot, but not as smooth as before. Upshifts were definitely noticeable. Before you'd barely feel it. After I got on the freeway and got it up to 60mph for 2 minutes, I couldn't replicate the problem again. I tried stopping and accelerating. Things were back to normal. I think that cursing at 60 cooled things down?
What could've caused this? What I felt, is that what is called "transmission slippage"? Maybe it's because the car was running really hot all day? I have never checked the ATF level. I am going to check it tomorrow. I don't think the ATF has ever been changed by the previous owner in Japan. I don't wanna sound like a wimp, but I am saddened by this. This car has been perfect since the day I got it. Just really worried that then trans is messed up.
My 07 RX8 6 speed GT did what you describe 2 weeks after I bought it new. The dealer checked the ATF, and DRAINED about 1 quart.
Three years and about 22k miles later the trans imploded aNd ran in 3rd or 4th gear on way to dealer for new warranty trans.
I suspect the torque converter wasn't filling properly, and dropped its contents into the fluid, so it became 1 quart low.
You should check fluid level, and get a Scanguage II plugged into OBI port to monitor ATF temps. You can get the programming xcode offg net from some Miata guys.
After I even put a small 14k btu cooler on it, I got 245 deg F on a track run, and 249 is limp mode.
I reinstalled a 18,800 btu ATF cooler, the biggest that can slide into the opening without taking pan off, and it takes exactly 14 deg out of the temp.
You have a way to also take temp out of engine by putting it in line after it goes through radiator.
I can drive 100 mph in 100 deg weather, and water is 193, and ATF is 193.
Also, I can heat up car on a 70 deg day to get temps up to 190, and then cruise at 30 or 40 mph, and temps will go back down to 175 water and ATF which is closing the thermostat.
Thanks for the reply. Yes I'm gonna check the fluid level asap. Is it ok to top it up with a different brand of ATF? I know this car needs JWS3309. Any brand is fine, right?
I thought the car doesn't have an ATF temp sensor. Why did the dealer drain a quart? That's messed up
You over heated your transmission by sitting in traffic for so long. Have the fluid checked, add a bigger/more coolers if you think it will be a continuous issue or turn the car off if sitting in traffic for too long. heat soak sucks.
The ideal fluid temperature is under 175 degrees, but as fluid ages it starts to break down and lose its capacity to cool down the transmission. This is when transmission overheating occurs. At 220 degrees, varnish forms. At 240 degrees, seals start to harden. At 260 degrees, you’ll often experience transmission slipping as plates slip. At 295 degrees, seals and clutches start to burn and fluid forms carbon, at which point transmission failure might happen soon.
You over heated your transmission by sitting in traffic for so long. Have the fluid checked, add a bigger/more coolers if you think it will be a continuous issue or turn the car off if sitting in traffic for too long. heat soak sucks.
Thanks for your reply. I went through that post earlier today. Got a couple of questions if you don't mind.
Was that transmission slippage I felt?
Is it normal to overheat like that? Or is there something wrong with the car? I was able to shift into manual mode. I've read that when it overheats it locks you out of manual mode.
My car is RHD. I don't know about the LHD cars, but in RHD cars the center transmission tunnel eats into the driver's footwell a lot. I know the cup holders heat up due to the CAT. But I also feel a lot of heat where the driver's footrest is. Is that heat from the transmission, or the CAT?
The AC wasn't cool enough. Any idea why that happened? The coolant temps were fine, by the way.
Thanks for the reply. Yes I'm gonna check the fluid level asap. Is it ok to top it up with a different brand of ATF? I know this car needs JWS3309. Any brand is fine, right?
I thought the car doesn't have an ATF temp sensor. Why did the dealer drain a quart? That's messed up
Trans is common to Toyota so I have Toyota JWS3309 fluid that I filled cooler as I put on.
I think most cars have temp sensor. I don't know if you can get code for 4 speed, but it might be same as 6 speed.
The dealer drained a quart because it was quart over filled. As I said, it's possible it was filled correctly at factory, but torque converter won't stay filled when turned off to check.
Trans is common to Toyota so I have Toyota JWS3309 fluid that I filled cooler as I put on.
I think most cars have temp sensor. I don't know if you can get code for 4 speed, but it might be same as 6 speed.
The dealer drained a quart because it was quart over filled. As I said, it's possible it was filled correctly at factory, but torque converter won't stay filled when turned off to check.
If I am low on ATF fluid, is it ok to top it up with some Toyota JWS3309? I'm mentioning Toyota because i have a feeling that it'll be readily available.
I have revision C coils, so I'm hoping they'll last for a while.
I checked my engine oil today. It was at the pink arrow, so I'm guessing a little low. I topped it up to the green arrow.
Took the car out today. It was 98F outside. Today's a poya day. Roads were fairly empty so didn't get stuck in traffic. Everything seems fine now! The AC was blowing ice cold again. The foot rest area wasn't getting too hot. No transmission issues.
Could this be because I topped up engine oil?
Also, is the heat I'm feeling at the foot rest (RHD car) the transmission heat, engine heat, or the CAT heat? Or all three?
Adding 1/2 quart of motor oil would have no effect on what you described. I'm going with heat-soaked transmission. If it were my car, I would just drive it as usual and not worry about it, unless it becomes a frequent thing. Since these cars run hot, think about shutting it off and rolling down the windows, if you are going to be stuck in one place for a while.
Adding 1/2 quart of motor oil would have no effect on what you described. I'm going with heat-soaked transmission. If it were my car, I would just drive it as usual and not worry about it, unless it becomes a frequent thing. Since these cars run hot, think about shutting it off and rolling down the windows, if you are going to be stuck in one place for a while.
So what happened is completely normal? I've been thinking my transmission is messed up :/
Haha good point. I'm just super paranoid. Heard too many RX8 horror stories lol.
Is it the transmission heat I'm feeling near the footrest? Or the catalytic converter? Im feeling a lot of heat down there. I know the cupholders heat up due to the CAT. But that area doesn't seem to get too warm. I have a gutted cat though.
There will be lots of heat going down the tunnel in center of car no matter with cat or not.
It's a very hot running car, and I live in the Texas desert, and don't drive it if temps are over near 100 deg f.
Here's what you do: buy a tube and fin 18, 800 btu cooler and put instead of gravel guard in front of AC radiator.
When plumbing it in, you can see if the fluid is bright red or just brown. If it's red, I might check level out fluid without change.
You need to check level anyway if you ever thought it slipped, so you may as well change fluid with about 12 of those bottles. I'm not sure what it holds, just look it up.
1. I have no experience with AT RX-8s, as I refuse to work on them. I do know that many modern automatic transmission are very particular about how their oil is drained and filled, and the process is often controlled by a machine that interfaces with the ECU. Not sure if it applies to the 8 or not, but messing with transmission fluid without the proper equipment can result in a wrecked transmission. I have seen it happen many times. Because of this, replacing ATF is a dealer-only proposition for me.
2. A transmission oil cooler could be a very good idea in your climate. There are a lot of brands out there of differing quality levels. The gold standard coolers are made by Setrab, which includes Mocal and a few others. A high quality budget line is the TruCool series made by Long.
3. If life on your island consists of a lot of idling in traffic in the heat, the RX-8 might be the worst car you could have chosen. You need a grocery-getter for that. The 8 is made for revving high while carving mountain roads and the like.
4. Like 40w8, I live in Texas. It gets HOT here in the summer. Like 110F in August. I don't drive my car when it is over 95F. That is what my daily driver is for.
5. You might be on to something with all your talk about fans. A good course of action for you might be to upgrade your fans to the highest CFM shroud that will work with your stock wiring (or upgrade your wires and relays to go bigger). The trade-off will be noise and vibration.
6. Maybe just enjoy your car and stop worrying.
7. An automatic transmission?! Really?! I have lost all respect for you.
Thanks for the replies guys! Yes but where is the heat mainly originating from? Mostly from the transmission? I will check the fluid level. I don't think I'll go as far as fixing an ATF cooler though. Money is limited lol.
I do have a daily, but I try to take this out as much as I can because I love driving this car so much! Even being stuck in traffic is cooler in this car The Bose sound system is so clean!
Yeah I am looking at a set of FAL 420s. Importing them here is the problem I don't have any overheating issues though. Temps mostly stay below 220F.
Haha I didn't have a choice. This was the only car I could import into my country. You can't import cars that are older than a year, so I thought to myself, an automatic RX8 is better than no RX8
Heat in the trans tunnel is generally from the cat. Our cat reaches 1800F under load. At idle, it sits around 1400F. That is still hot. Magnaflow warranties their cats to 1200F, for example.
Since your car is LHD, your left foot rests against the exhaust manifold and downpipe.
Heat in the trans tunnel is generally from the cat. Our cat reaches 1800F under load. At idle, it sits around 1400F. That is still hot. Magnaflow warranties their cats to 1200F, for example.
Since your car is LHD, your left foot rests against the exhaust manifold and downpipe.
My car is RHD. It's a JDM model. I was monitoring the cat temps. I have a gutted CAT, so my temps are around 1100F at idle. It gets up to around 1700F when flooring. The CAT temps were the same as before, but the footrest area was feeling extra hot.
I meant RHD. My point wouldn't make sense, if it were LHD. My bad.
Why would you gut the $1500 (double that where you live) cat on a brand new car? Just keep the ignition healthy and keep the cat. Too late, I guess, but I'm shaking my head over that one. My car has the factory cat back on it right now, because I am busy tracking my Miata.
[For anyone else reading this... DO NOT GUT YOUR CAT IF IT IS HEALTHY. Buy a BHR midpipe and keep your cat. You may want or need the factory cat in the future. If you later decide you don't, you can sell it to someone who gutter theirs, and make your BHR pipe free.]
According to my testing, EGTs are nearly identical with or without a cat. Since I don't really sit in traffic when driving my car, my temps are probably different than yours. Mine runs around 1800F under load, around 1600F when cruising, and around 1400F when stopped at a stop light, for example. Pretty sure I have posted some graphs of mine around here somewhere.
If you upgrade the fans, be sure what you are buying is actually an upgrade. CFM ratings are measured different ways, so a 1500CFM fan measured at one distance and pressure may actually be an 1100CFM fan measured differently. Also, the design of the shrouds is equally as important as the flow rate of the fans for your driving situation. If you do mostly highway driving and track driving, you want as little shroud as possible. If you do mostly city driving, you want as much shroud as possible. You also want a flap system that will open at speed to allow some air to pass through the shroud, if possible.
My car came with a gutted CAT from Japan From what I've read, a gutted CAT gives more performance than even a healthy cat, so maybe that's why. I've never seen 1800F. I've had my CAT temp gauge show the minimum and maximum values. The max is always around 1720F. At idle it's around 1200-1100F.
I'm thinking of adding an axillary fan from the front of the AC condenser. I can pick up a used axillary AC fan from an old Corolla for like $10. Think that will help with cooling? My problem is the AC condenser. Whenever I turn on the AC in 95F weather, the coolant temp slowly creeps to 220F and keeps climbing. As soon as I turn the AC off, temps drop back down to 206F (that's when the fans go to low speed). So I guess the heat the AC condenser puts out is too much for the radiator to cool the coolant. I've also noticed that turning the AC down to the lowest fan speed keeps the car's coolant temps low. It still rises, but it stops at around 217F.
You get a slight boost in HP from gutting a cat. We are talking 1 to 3HP at 7500RPM, where 1% of your driving happens. I would much rather have the cat and skip the rotary stench, than have a few extra HP I can't really feel.
A pusher fan on the front may help some, but it also creates an obstruction to air flow. The most efficient route would be stronger pullers. Did you ever try the fans on low mod, after I spent all that time collecting data for you?
Or, just turn off the AC and roll down the windows. This car isn't a Camry. Sports cars come with compromises. OTOH, Mazda sure seems to think those temps are safe.
It seems I had my EGT numbers confused in my head between tracking daily driving. My car also peaks at 1720 during daily driving. It still runs hotter than most cars, though.
Here is a data log of daily driving that was taken in February. Things are probably a little hotter during the summer.
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Last edited by Steve Dallas; 04-13-2017 at 08:50 PM.
You get a slight boost in HP from gutting a cat. We are talking 1 to 3HP at 7500RPM, where 1% of your driving happens. I would much rather have the cat and skip the rotary stench, than have a few extra HP I can't really feel.
A pusher fan on the front may help some, but it also creates an obstruction to air flow. The most efficient route would be stronger pullers. Did you ever try the fans on low mod, after I spent all that time collecting data for you?
Or, just turn off the AC and roll down the windows. This car isn't a Camry. Sports cars come with compromises. OTOH, Mazda sure seems to think those temps are safe.
It seems I had my EGT numbers confused in my head between tracking daily driving. My car also peaks at 1720 during daily driving. It still runs hotter than most cars, though.
Here is a data log of daily driving that was taken in February. Things are probably a little hotter during the summer.
.
Haha yeah it does reek.
Stronger puller fans are expensive Slapping on a pusher fan would cost me $20 max. And I really don't wanna take apart the radiator and risk breaking the coolant nipple.
Thing is, I only run hot after stuck in traffic for an hour. By that time, my car goes into a sort of fail safe mode, and run the fans on high speed all the time! Idling, driving at speed, it's on full speed all the time! Restarting the car doesn't stop it. If I stop the car, leave it for 30 mins and start it again, then it'll only turn on when the temp gets high. But again, if I get stuck in traffic for an hour, it'll do it again. I've started a thread on this. No one seems to know why it's doing it. I've looked at the fan control diagram, and there's one where it says "Fail Safe", where the fans would run on full speed if something's wrong with the coolant temp sensor. That's the only thing I can think of. My car spends most of its time over 203F. 203F is when the fans go on low speed. That, coupled with the crazy high speed fan behavior, I didn't have the need to do the fans on low mod.
Yeah I turn the AC off and roll down the windows. Downside is the humidity is very high. I sweat like a madman upside is I get to hear that beautiful R Magic exhaust
Nice. Your car drops to 1300 when idling. I think I've seen this chart before Do you floor it when driving it daily? Mine only reaches 1700+ when flooring it.
Thank you so much for taking time off and explaining things to me! Really appreciate it!
I logged that driving to work one morning in February. Ambient temp was probably in the 30s. There might be one WOT pull in there. I drive this car in a spirited manner, but I don't have a lot of opportunities to go crazy with it during my Friday commute.
Perhaps you should skip straight to the fans on high mod!
04-06-2017, 05:16 AM
The Bose sound system is so clean!
From what I've read, a gutted CAT gives more performance than even a healthy cat, so maybe that's why. I've never seen 1800F. I've had my CAT temp gauge show the minimum and maximum values. The max is always around 1720F. At idle it's around 1200-1100F. 
