Rajareits

So hello again, after a while.
Got some quick questions again..

My coolant temperature is about 200-210F when driving normally (well, as normally as you can hold yourself). But when I'm just revving, standing still, it goes incredibly hot in a matter of seconds. Is it happening to anyone else also?
At the moment, I'm thinking of tampering with the fans to cool it better..

Thanks guys!

9krpmrx8

iTrader: (46)

I wouldn't tamper with anything, you just need to make sure that the systems in place are working as they should be.

Rajareits

Yeah they are, but I'm not 100% satisfied with them. :D

badinfluence

I would take a look at the car's reported Coolant Temperature, then look at the Coolant Temperature voltage via OBD/ISO CANBUS.

Then look at the Air Fuel Ratio Commanded then compare that value to Air Fuel Ratio Actual. (12-14.7 under Load, 14.2-15.0 idle/neutral) The Actual and the commanded should be very close, but if they jump out once or twice do not worry. But if they are constantly off, check your Long Term Fuel Trims and Short Term Fuel Trims.

LTFT should be + or - 8%, STFT just look for it to be changing, but not going berserk.

Then Check the Catalyst Temperature. (900-1700max)

If the Catalyst temperature is shooting up as fast as your coolant is, then the car starts adding LTFT, then start looking for a problem in the exhaust, intake, or inside the engine. (Inside being the worst of all)

Rotaries get hot, and they get hot fast. The Catalyst is a restriction if it is going bad, and it has no business even existing. It is from the days of Carburetors and loose as **** slutty factory tuning. Now a days you can run a car way leaner at idle and under load because ECUs are faster and smarter to the point they just spend time adding fuel to prevent the car from catching fire. If it wasn't there, you wouldn't need to add fuel completely reversing the purpose of the little ******. (The Catalyst and Rear o2 sensor)

Loki

iTrader: (1)

The stock cooling system should be able to handle all but the hottest tropical weather.. so something's wrong. Some common issues to check for:

- radiator cap leaking/hissing and not holding pressure
- cracked overflow bottle
- coolant leak inside the engine (when the car is cold, remove the rad cap and start the car. If you see bubbles in the overflow tank, you likely have a coolant seal failure)
- have a cooling system pressure check performed to confirm/deny any of the above.
- rad fan failure (if the fans don't come on around 190F, something's wrong with them)



Not sure about the cat idea. By all means check it out, but it wouldn't be solely responsible for you running hot. Considering you found dead spark plugs, the cat could be damaged also. You replaced the coils already right?

badinfluence

To add to what Loki said, that Coolant Temp Sensor and Bottle (the one mentioned above) are bad news. Also when replacing it, MANY less than par mechanics break off or crack the top nipple of the radiator. That sensor and bottle are commonly bad on many RX8s, even a series II like mine. Not sure why, maybe Loki knows a bit more.

Nisaja

I just came across this thread. I'll start from the top haha.

I'll tell you how to measure how fast your car is.
Step 1: go on YouTube.
Step 2: type "RX-8 0-60"
Step 3: get a stopwatch
Step 4: TIME IT

Time a couple of videos to get an average. Now hop back into your car, strap the camera to the steering wheel so it records the dash, find an empty road and do some 0-60 runs. Go back home. Put the videos on your PC and time them with your stopwatch. Compare them with the videos on YouTube. 100% accurate way to measure how fast your car is

The oil pressure gauge is supposed to stay one tick above the middle position.

Regarding the temps, you are fine. 200-210F is normal. What are your ambient temps?

They do get hot when revving while idling. Why would you want to do that anyway? How hot does it get?

The fans don't come on at 190F. They have 2 speeds. They come on low speed at 206F. When they're on low, you won't hear them. If you get really close to the front bumper you'll hear them. Then they go on high speed at 213.8F. You'll definitely hear them when they're on high. When they come on at 213.8F, they'll go back to low speed once the coolant temp drops to 206F. If you have the AC on, the AC can sometimes force the fans to go on high when the compressor is on. So now you know that if the fans are on high when the coolant temp is 200F, it's because of the AC :P

The center armrest area does get very hot, because it's right above the catalytic converter. Check the cat temps from your obd2 adapter. What's the temp at idle? How hot does it get when driving?

Nisaja

Uhh, not true. I have a friend who's oil pressure gauge moves on hot days. I know another car with the gauge pointing way over to the right. Weird, I know. I thought it was a dummy gauge too.

Loki

iTrader: (1)

Are you sure it's not the temperature gauge moving? The pressure gauge is attached to a switch, so it only knows if there is pressure or there isn't, but it doesn't know how much. Also oil pressure depends on rpm, so a real pressure gauge would bounce around while you drive...

Nisaja

Pretty sure it's the oil pressure gauge man. I don't know what kinda gauge it is but it moves alright! I saw it on a different car a while back. I think I had a picture. Let me check.

Nisaja

Dun dun duuuuun

Rajareits

Thank you guys very much for answering!

The temperature is a must on almost every startup. Whenever I get on the track, I always have a passenger with me who constantly monitors the temperature. But the voltage? Do you have a table on where it should correspond?

Thanks, will do!

Actually I've already got rid of the cat with the rear sensor. It built heat, although I was expecting it to add more.

Yes, I agree.
At the moment, my main concern when driving is the water pump. If I can really floor it (every gearchange exactly before the limit), then it get's hot. But when changing at about 8500 rpm, then you can drive as long as you want.
But I can't figure out why it builds so much heat so freaking fast when standing still.. Although, I have to say, I've never revved and checked the temperature at the same time on any other car.




At the moment I only know that the coolant is not disappearing.
It should be airtight also (or was, I'll check that later).
The fans I think work properly. I never leave the car when it's hot, although I accidentally heard one just this weekend (I didn't think the engine was hot so I didn't check and turned the engine off).

The coils and spark plugs are replaced.

Yeah, I've got the coolant light on while driving on a circuit hard or cruising with 4000 RPM (or higher I think).
At the moment, I'm not worried about this..


That's clever, why didn't I come to that?
Although, I have to say, I'm now pleased with it. It took time to get the engine to run well.

Thanks!

I'd say about 203F or even lower when driving on public roads. Freeways even less.
But the revving. It's just that.. You know... FLAMES!

Thank you! That's why I can't hear them.. :D
The armrest is now much cooler without the cat.

Also, one more question..
How high do you usually let your temperature go? On the track I mean.
Just made a quick search through the logs. My record is 230F (I backed down then). It's a bit much I think.. This was the first time I went on the track (the previous day I removed the cat). After the trackday, the car finally started to drive like it should (cuz it was free from the horrors of carbon).

Nisaja

Haha the flames. Cool stuff. Watch the temps while doing it. How high does it get when you're checking for flames?

230F is high. Although some say it's a myth, many believe that you can lose a coolant seal above 230F.

I don't let my car go above 220F. I live in the tropics, ambient temps range from 30 to 40C.

Rajareits

I usually do.
I don't let it go very high. It usually jumps to 220F. But it bothers that it jumps so quickly. Smooth heating is not nearly as bad as those peaks. For example, in DTM you have to warm your engine for two hours just by pumping coolant warm coolant through before you start the engine.

Your car seems very cool. I guess you don't drive it like you stole it?

So far, I understand that everything is normal...? Just that, I need it better.
New water pump and change of fan speeds should do the trick..

Nisaja

My engine doesn't run cool :P I've had my fair share of overheating issues. In 95F (35C) weather, my car hits 220F while sitting in traffic. When I start to move, it goes back down again. The stock fans aren't capable of keeping the temps below 220F in hot weather.

Revving it in one place does increase the temps. As long as the temps drop when you let go of the throttle and let it idle, It's normal. Don't worry about it.

Yes, getting faster fans will definitely help. Do the fans on low mod. It should help lower the temps when moving.

I'm not sure about the water pump though. Unless your stock pump is faulty, it's not going to do much.

Try sealing around the radiator. That should definitely improve cooling.

Rajareits

Thank you!

I've heard (and experienced) about the cavitating issues with the original pump, so I'm thinking about the MazMart one.
As I said, there's no big issue when driving to the redline, but when you go over it with every gearchange for over 5 minutes, the temps are not that pleasant anymore.

Loki

iTrader: (1)

The Mazmrt pump will help on the circuit (personal experience). In regular driving it doesn't change anything

Rajareits

That's what I'm hoping for..
It's just somewhat expensive, especially if I actually don't know if I can make it to the track that often. TBH, the best would be to get the impeller from somewhere. Or make it myself..
How much did your highest temps fall?

Also, if anyone's interested, I use Motocool Factory Line in my system, without water.

Nisaja

Didn't 9krpm say it did nothing?

Loki

iTrader: (1)

I don't have a 9krpm gauge in my car, only a temp gauge.

It probably does nothing for the average joe driving around town, because average joe is not limited by the water pump flow rate at high rpm. For me it's the difference between 222 and 212F after 20 minutes on track.

Someone who hasn't posted here in a long time did a computer simulation using I'm not sure what data and ignoring a whole bunch of factors and concluded that the stock pump flows better than the remedy pump up to 12,000 or something like that. Make of that what you will, but again, I don't have a computer simulation gauge in the car, only a temp gauge.

200.mph

iTrader: (9)

a 9krpm gauge, lol thats funny ****

Rajareits

That's what I wanted to know!
But it seems good to me with the original pump. What else had you done previous to the pump change?
Also, the weather in Montreal is quite well suited to circuit racing?

Loki

iTrader: (1)

I did the thermostat and the water pump at the same time. Those are my only cooling mods. I think the AccessPort tune might also change the fan start temperature, but that was done long long before. Coolant has always been Mazda FL22.

Rajareits

Thank you!

I also can't decide about the AccessPort. Should I go with it or not?
Positives for me at the moment are the fan-mod and CEL (which I can delete with my phone also). Negative - the price, again.
How much is the the engine map better than the stock one?
Water pump or AccessPort? :P

It's just that, the car works very well, the cooling mods are just a possibility. I don't need them definitely. I can just lift the throttle after couple of laps you know.
A set of new slicks or a donation to "let's buy an another car" fund are also inviting.

Loki

iTrader: (1)

One is $160 or something, the other is $600+.. soo.. you know
The Cobb by itself isn't super useful, you have to get it tuned by someone. Not sure if MazdaManiac is still in business, but I had a good experience with him and the tune does all the things it says it should.

The water pump will only help you at the track, so if you have heat issues in regular street traffic (if I understood above correctly) then fix that first. I'm from Eastern Europe too, pretty sure it's not over 35C in Estonia at the moment.

By the way, heat on the track depends on the track speed also. At Mont Tremblant, which is a high speed, smooth course, heat is not a problem regardless of ambient temp. At a smaller local track (1.4km) with a lot of low speed maneuvers, in really hot weather (30C+) I get to into the 220F+ range.