pricer01

Folks

I've recently passed through the 5000k milestone and there seems to be an atypical transformation of my perceptions of the car.

Everything I've owned previously lost most of whatever 'wow factor' they had by 5000k.

Not only do I enjoy and thrill to the 8 more each day, but it seems to be getting more powerful. I know I read in a post a while back about some supposed ECU change after 5000k but I dismissed it a folly ... but now I'm not so sure.

Am I just a pathetic love sick puppy or is something changing .....

(Before my MATES get the chance maybe I'll amend the question ...)

I know I'm just a pathetic love sick puppy but is something else changing??????


Rob

Kev

I hope something changes. It'd be nice to feel more power at higher revs instead of "more of the same". I'm not unhappy with the performance ... but call me Oliver

Wildcard

It's an interesting one... Some days I think there is more power post 5000km, but other days I'm not as convinced. It's now been so long since I went through the 5000km barrier that I can't even remember what it used to feel like. As I said a while back, the ultimate test would be at a drive day to go for a quick spin in a car with <5000km on the clock, and then jump straight in one with >5000km. Your butt dyno might pick something up if it's there at all.

DMRH

This is just a theory.

The FD RX-7 (92-02) had an input called a "Mileage switch". At 10,000km the switch activated & ran the idle around 100rpm higher. This was to compensate for the compression dropping to its normal level after the run in & honeymoon period.

To do this, the ECU ran the engine richer. Fun part is that it did it throughout the rev range (I originally though it was idle rpm only)

The richer mixture resulted in better performance, especially for a turbo car.

Perhaps the RX-8 is the same at 5000km.........????

Wildcard

Interesting....

It appears that the guys in the US are blaming the lack of power in their RX-8 on the fact that the ECU is running too rich - the opposite of what's said above. I'm pretty sure that in Canzoomers ECU upgrade, he has leaned out the air/fuel ratio to gain more power.

Maybe it was different in the FD though because of the turbo(s)??

Wildcard

I have some other possible explainations for the percieved increase in power post 5000km:

1) Since this is a "learning" ECU, the more km's you put on your car, the better it perfoms because it has learnt your driving style.

2) As you get more and more used to driving the car, your driving skills improve and hence you are smoother and able to get better performance than the day you drove it out of the dealership.

Just my .02

DMRH

A learning ECU.......??

There was no mention of that in the technical press pack given out at the launch. I have just read it again to make sure.

THis is an interesting theory........

I also agree that the richer the mix, the better for the turbo's & worse for the atmo engines. Didn't think of that part.......DOH!!!

Wildcard

I'll try and find some proof for the "learning ECU" quote. I'm not sure what my source was, or where/when I read it, but I'm pretty sure I didn't make it up.

In fact, I'll PM Canzoomer right now. He ought to know for sure.

DGW

Wildcard

Here is my PM to Canzoomer and his response. I'm pretty confident that he knows what he is talking about, given that he has just mapped the ECU and come up with a new set of fuel maps for his own mod:


quote:
--------------------------------------------------------------------------------

D.G.W. wrote on 11-17-2003 05:12 AM:
Canzoomer,

Is it true that the stock ECU in the RX-8 is a "learning" ECU - i.e. it adapts to your driving style over time?

I just made this claim in another thread, and someone asked me where I read it. I can't remember, but I'm sure I didn't make it up.

No need to explain to me how it all works, just a simple "yes it is" or "no it isn't" would be appreciated.

Love your work by the way.

Cheers from Down-Under,

DGW

--------------------------------------------------------------------------------

The response:

Re: Learning ECU?
You are correct, it does "learn".
It is not a very complicated thing, however.
And it only takes about 15 minutes.

--------------------------------------------------------------------------------


So yes, it is a learning ECU, however it doesn't take 5000km to learn your style of driving - more like 50km. There goes my theory, but that's cool. I love learning about this car.

DGW

timbo

Have heard of "learning" ECUs before, but was under the impression that which is "learnt" is pretty minor -- mainly fuel trim for emission purposes after the ECU identifies a consistent driving pattern, and relates mixture and cat. converter temps reached.

I'd be interested to discover if the 8's ECU covers more than this in terms of the other parameters the ECU monitors and are thus changeable.

Would a complete battery disconnection reset the ECU to its original state? I think probably not -- that was the case with old ECUs, but I would imagine the modern ECU uses flashable EPROMS that save their current state in the case of a full power (voltage) loss.

Hence giving rise to the modern tuning practice of 'remapping'.:p

Apologies, am rambling along here thinking on keyboard, and now appear to have reached the point many others were at weeks ago

MadMAX

I have a Subaru that has a "learning" ECU... but all it does is adjust mixture and timing depending on fuel quality. At least that's what Subaru told me
It apparently takes about 2 tank fulls of fuel like Optimax before it figures out that you have a "better" fuel and adjust accordingly.

Cheers,
Max

Kev

How about a better fuel NOT like Optimax?

timbo

The fuel issue is interesting. The CarPoint review (another thread) says Aus 8's power output is 8Kw down on overseas because of our lower fuel standards.

But surely if you run Ultimate 98 and the ECU 'learns' then this ought to be overcome.

Hmm, timbo, another naive statement. Better have a beer!

Wildcard

Going back to the re-learning thing, I think it resets pretty quickly, i.e. it is constantly learning. As Canzoomer said, it only takes about 15 minutes, so if someone else drives your car for any longer than that, it will adapt to their driving style. Once you get back in the seat, it quickly learns your style again.

I also remember reading (somewhere on the forum) that any mod will reset the ECU, eg installing an aftermarket exhaust. A soon as it detects a change in engine parameters, it will do its thing and learn the changes to optimise the way it runs. Ditto if you change the type of fuel you are using.

Also, the higher power figures for Jap '8s is because the car over there is designed to run on 100RON fuel. The best we can do is 98RON.

DMRH

If you can find a copy, The WANKEL engine by JP NORBYE is a great read.

It has technical date from Curtis Wright doing octane level testing on there RC260 engine.

Rotary Combustion 2 (rotor) 60 (cubic inches)

They used a variation of RON from 85 - 105. Good news was that the rotary ran well for all grades of fuel tested, They stated that the lower RON fuels required some re-jetting of the carby (from early 70's) but that was it.

A piston would have pinged & exploded under the same conditions as compression ratios are critical for the RON used.

Bad news for us was......... less that 3hp difference in power from the lower to upper scale of fuel.

Thus, 91 RON unleaded should (according to this book) produce practically the same power from your RX-8 as the 98 RON Optimax fuel does.

Main difference can be found in your hip pocket I guess..........

Turbo rotaries are another story.....

Australia was to get the 184kW ECU as the Jap version does, it wasn't the fuel issue that stopped it, as the reasons above show that. The actual reason was our pending Euro-IV emmisions standards coming in for 2005. The 184Kw ECU can meet the current Euro-III but not the Euro-IV standards. Mazda Australia didn't want a power drop for the RX-8 a little over 1 year after release when customers would be already expecting more power. That would have really smacked you in the face hey!!!

Give the dumb Aussies the lower powered ECU to start with & there will be no whinging come 2005 when the Euro-IV standards come into effect.

I'll just buy a used 184kW ECU from a smashed RX-8 in Japan come then.............

Kev

If you can open up a channel to get a few of them ....

rpm_pwr

DMRH, where did you get the idea that Euro 4 is coming for petrol vehicles? According to DOTARS they are only planning Euro 3 next year.
http://www.dotars.gov.au/mve/vehicle_emissions_adrs.htm

While looking around their site I also noticed that OBD is part of the Euro 3 requirements:
http://www.dotars.gov.au/mve/emission_requirements.htm
hmmmm

-pete

Wildcard

I can verify that. I've run two complete tanks on 91RON regular unleaded thorough my RX-8 with no noticable difference in performance or driveabilty. I'm only back on PULP because the manual and Mazda recommend it, even though no-one can explain why. The only explaination I've been given is that Premium is a "better quality fuel with fewer impurities". A lot of guys in the states are running 87 octane (91RON) and swear by it.

That makes sense if changing octane has an almost negligable effect on hp as you suggest. Certainly not 7kW! I don't know why it hasn't been explained to us like that then. Everywhere I've read the 177kW vs 184kW argument, the reason I've been given is that it's because Australia has "lower quality fuels".

DMRH

Now you have made me do it.

Made me get off my bum & get the Rx-8 press pack out of the cupboard & look it up again.........:D

Mazda Australia gave this out to the journo's at the Coffs harbour launch. It states that the 177kW engine meets our Euro-III standards.

Talking to a Japanese Mazda engineers present at the time. He was asked about the change from the 184kW ECU to the 177kW ECU. He spoke about the pending Euro-IV standards for 2005 & how the 184-ECU doesn't meet them

I put the fragmented picture together & came up with the assumption that the change to the 177kW ECU was to prevent a sales backlash when Mazda would have been forced to change to meet the emmisions.

As for what standards we have & what is pending, I must admit ignorance. I have simply listened to what I was told by accepted experts. If I am wrong on the Euro-III/IV issue, please forgive me.

rpm_pwr

haha no I was just worried that Euro4 was coming soon too.

Basically, we're a step behind the EU. They're on Euro3 now and moving to Euro 4 in 04/05. We're on something similar to Euro2 and moving to euro 3 in 05.

That's why european rx-8's copped a bigger reduction than we did. But both for the same reason I gather.

One good thing - The european rx-8 has less CO2 emissions (and better fuel economy) that the 350Z, which doesnt seem to meet Euro4 at all.

-pete

Dez

hmm...

I really have to dedicate a whole weekend to pulling the system apart and finding out more about it..

--dez;