r0tor

iTrader: (1)

This makes NO sense at all. How can the traction control work by taking the difference between rear wheel speed - we have a limited slip differential that tries its damndest to eliminate rear wheel speed differentials.

All traction control devices in existance work by comparing wheel speeds of the front tires to the wheel speeds of the rear tires - the difference is how much the drive tires are spinning. It then looks at the throttle and brake positions to determine what is going on - basically are the rear wheels spinning due to power or are they "spinning" because the front wheels have locked up causing the wrong signal. The only other way I have ever heard about it being done is in Formula 1 when TC was banned - then the teams used barometers in the air intake to get the pressure and correlate it with maps to approximate a speed.


I don't understand the logic that you state activates the DSC (i'm assuming your including traction control in DSC?). Are you saying its rear wheel slippage AND 40% steering angle? If this were the case, it would never activate on a burnout (just try doing a burnout with DSC on - its not happening) since the wheels are straight. If it was either of the signals alone, the DSC would be going off when you turn into a parking spot.

A true DSC program takes all 4 wheel speed sensors and steering wheel angle. From the 4 wheel sensors it can calculate a yaw rate of the car. It then compares this calculated yaw rate to the yaw rate supplied by the steering wheel angle - if they don't match there is trouble. This data is then compiled with input from the traction control system. You now have steering, throttle, brake, and all 4 wheel speed information running into the same system. Accelerameters are also quite popular, but not necessarily needed.

Also, I can guarantee you my DSC has gone off due to loosing the rear end while off the throttle with steering inputs much less then 40% already.

canzoomer

I was not concerned as we in Canada did not get this feature included on our cars.. But, I feel your pain..

OK, let's have a peek..
The TPMS uses an RF sender in each wheel.
These send to sensor receivers in the wheel well area.
No separate fuse is shown for this system (bummer).
It is wired in the same harness as most of the dash area sensors and connections, so isolating the wire is tricky.

The wiring all feeds to the TPMS control module, which is under the dashboard, behind the centre console panel.
Labelled C2-01
To get at it one has to dismantle the centre console area ( the area that holds the audio system, temperature controls and optional NAV system).
I think disconnecting that module is your best bet.
It has an 16 terminal connector, with 5 wires in it used.
The wires are colored L/R, B/Y G/B L/W on the top row, and a single wire coded B on the bottom row.

Code legend for colours:
L=Blue
R=Red
B=Black
Y=Yellow
W=White
L/R means a Blue wire with a Red stripe.

Good luck!

canzoomer

No apologies needed. It is a complex set of systems. The wiring manual is 169 Pages!!

However, there is NO TC system.
The systems are ABS and DSC (Dynamic Stability Control)

There is no subsytem called or anything that mentions a traction control (TCS).

For DSC there are sensors that monitor rear wheel slippage and front wheel turn angle past 40% turn.

The ABS monitors the 4 wheel speed sensors.

Pressing the button briefly disables the DSC, unless it is triggered by ABS signal, whereby it re-enables (Thanks to somebody for that tip about the ABS re-enabling the DSC, you are correct).

Holding the button in competely disables the DSC, ABS input or not, and keeps it off until the car is turned off and back on again.

One can also produce the same result with disconnecting the battery and reconnecting it.
Until the DSC is re-calibrated it stays off. This is because it needs to recalibrate the wheel position sensors.
The sensors are not proportional. They are simple switches.
They send a signal once the front wheels are past 40% turned. They stop sending the signal when the wheels turn back to centre, inside of 40% turned.

canzoomer

We have a differential that Mazda describes as a "Super LSD"
It corrects the slippage, but is not instant.
In addition it does not completely equalize the turn speeds, or it would not be a "differential"
What is does is limit the slippage when it exceeds a predesigned amount. It is still quite possible to slip a wheel to a certain degree. When the slippage is above turning radius differences, the measurements from the wheel sensors tell the ECU that a rear wheel is slipping. Above tha tpoint the DSC will certainly try and correct the condition.
All is a strong word. This one does not. One can disable the front wheel speed sensors (unplug them from the harness) and there is no DSC fault. There IS an ABS fault of course!
If one disables the REAR sensors one gets a DSC fault, however.
There is a pressure sensor on the RX-8, but it is used to allow for calibration of the Mass Air Sensor readings to be adjusted for air pressure.
No, it is a small degree of rear wheel slippage, combined with front angle, or a greater degree of rear slippage with no front turn angle.
It allows more rear slip if the wheels are straight. This is balanced with the amount of wheel speed differential caused by going around a corner. Remember, it is a differential unit!
Interesting. Possible cause may be one rear wheel sliding, so it slows down it's turning rate.
I wonder how it is correcting if you are "off the throttle" as you describe? It corrects slip by reducing throttle. That is why it is horrible on a track. When cornering hard, under throttle, you induce oversteer. If you back off the throttle you go into understeer, which can cause the front end to "wash out" and slide.

I have no static way to test for that condition.

In any case, I am looking at the engine, running at a constant throttle pedal position and rpm, and then enabling and/or disabling sensors, measuirng their outputs, and the resulting changes to ignition and fuel injection. Much of what i have said is interpolation from these tests.
Our goal is to increase power and mileage, mainly focusing on the rpm range above 6200rpm.
I simply tested the condition to determine if something "clever" in the ECU was defeating our tuning.
We did the tests static (on a dyno) and in the car on the road.
With DSC disabled while on the road we got the same readings as when static in the garage. Small differences in the Mass Air Sensor readings were detected, but that is due to air flow coming in the engine air intake. BTW, the stock intake system is quite good. it achieves about a 20% extra boost at 100kmh compared to standing still.
If somebody wants to build a cold air intake for this car and gain much, they are going to have to be very good at what they do. The stock setup has very little resistance.

vandal

"BTW, the stock intake system is quite good. it achieves about a 20% extra boost at 100kmh compared to standing still."

Are you alluding to some sort of a ram air effect going on here? Could this be where some of the missing HP is on the static dynos? For instance, if top speed is 136 mph (as some forum members have claimed to have reached), could Mazda be measuring top HP at that speed, thereby deriving the benefits of the increased air flow?

Please excuse my ignorance if my question evidences an abundance of it.

canzoomer

OK, got our main part of work on the fuel injection system mapping done.
Still have to do the ignition mapping.
Results so far:
Gain of 24.5HP at 8,000rpm
Gain of 11.3Ft/lb of torque at 5750rpm
This is on a Mustang dyno.

This is still using very conservative figures for richness/mixture.
No chance of knock on 91 octane gasoline.

Will be doing a fuel economy highway run tonight.

Will be doing ignition mapping in the next few days.

We feel we can pull another 10-15HP out of this with gentle settings.

At the present the emmissions level is still legal in Canada and 48 us states.
we would not pass the California spec.
It does not run clean enough inside of 5 minutes. Takes about 15 minutes to fully warm the cats enough to pass CA levels.

350 Formula

Not an expert, but most manufactures rate their engines based on a dyno in a building. If you get more horsepower due to ram air that is just a bonus.

boarder

canzoomer: what baseline are those hp numbers from (180?, or 200, 238) ?

or in better terms: what are the final/actual numbers you are seeing ?

BTW, keep up the good work. I'd offer help, but I don't have an RX8 (yet). I wish I knew more about these darned ECU's and how to hack them.

Dave

Reeko

Canzoomer..

Sounds awesome. I would love to gain 30-40 HP without any permantent mods to the car.

I volunteer to be a pre-prod tester if you need. (I work on computers for a living, but don't know anything about hacking auto ECUs. Sounds like fun though).

compaddict

Very nice work canzoomer. I missed what ECU you are using, what are you using?

Vince

canzoomer

Thanks for the offer guys..

Baseline I get on a Mustang Dyno is around 178HP (cold) and about 172 after some runs and heat buildup.

We did some more runs today, and started working on the midrange section, between 3700 to 6200
These are the areas where we run 4 out of 6 intake runners.
Surprisingly enough there is HP to gain in those ranges as well.
At the 6200+ we see it running way rich.
At 3700 to 5500 it is actually running too lean, which surprised me.
With a bit more fuel and some minor adjustments we are gaining 15HP in there as well now.
More importantly we see a gainof nearly 20 ft/lb of torque at 5000rpm.

We just started setting up the ignition controller, and will do some tests and runs on that tonight and tomorrow..

It is now dynoing around 204 to 210 HP on the Mustang dyno, at the rear wheels. The ECS is disabled from the dash.


I am hoping like crazy we get done for the weekend..
There is an amateur drag event going on at the local track and I want to try her out..

canzoomer

Original ECU is in place( it does WAY too much to be replaced) but we are bypassing the fuel and soon the ignition outputs, and are using a separate fuel controller and just installed an ignition controller. We will be experimenting with the ignition shortly.

Off to play!

syntrix

Keep us posted! Sounds like good results so far!

LL7

Since you are bypassing the fuel control and ignition, does this disable the DSC and cat protection circuits? How hard will it be to put it back to stock when you need service - I know its dishonest, but so is stealing our power.

O.R.A.

I'd like to understand how dumping a ton of raw fuel down the drain helps the cat instead of clogging it.

I just don't buy that "protecting the cat" deal. They could have plugged an exhaust temp sensor near the cat and then mess with fuel/timing/throttle position, etc. if the temps got so high that the cat could be in danger. That's what other manufacturers do. Simple and effective.

It just looks like the MazdaSpeed Protege ECU maps all over again. The ECU maps in those cars go crazy rich when they switch to open loop. So bad that Mazda just came out with a reflash because a lot of people were complaining about hesitation when the car switched from closed loop to open loop and the car would bog down. The reflashed ECU also freed up some nice hp increases.

canzoomer

We are allowing the DSC to continue to work. When the DSC cuts power, it causes the ECU ignition output to cut power. It does this by skipping signals to ignition. We are not altering that signal, except to change the timing of it. More or less advance as needed to make more power. If the signal does not exist we reflect that.

As for the "protecting cats" idea, I disagree with whoever came up with that. I believe they run them with richer mixtures to make more heat, so the cats work more efficiently, especially right after startup.. As I can not quote empirical evidence about that yet, it remains an "opinion".

syntrix

On the cat issues, I do have a K-type thermocouple as well as the wideband o2 that I need to install.

Maybe this weekend I can get it all wired and welded on.

I can also data log to a laptop, so I should be able to generate some good graphs, and we can see just how hot the 8 is running.

THC

Reply to previous Post

“I don't understand their use of the word "load" here. Surely, the load on the engine is the resistance it encounters as it attempts to turn the driveshaft. This would be a function of the weight of the car and the gearing (and at high speed the aerodynamic drag). So in the real world (as the weight is constant) high load simply means being in a high gear.

Are they saying that it will only produce maximum power in low gears?

And what about "the load quickly diminishes as the car accelerates in each gear". I don't understand that statement at all.”


I am a novice at this posting bit, but will add what I hope will be some help to the understanding of the above.

“Load”, is as you stated the resistance to the rotation of the drive shaft. When under acceleration in a lower gear, putting the weight of the vehicle into faster and faster motion is the load the writer was referring too. The load is reduced as the rpm begins to peak. This is a curve if it were to be charted. On the front side of the curve is the maximum load because this is where the greatest rate of velocity change takes place. As you go over to the back side of the curve and the rate of velocity change begins to decrease the “load” becomes less until a steady velocity is maintained due to no more RPM being available. At this point, “steady velocity,” the only load is then aerodynamic drag. All of this assumes the vehicle is being operated on a perfectly level even textured surface.

In the larger gears, aerodynamic drag becomes more of a factor. If you had a large enough gear where the engine rpm could not reach its RPM limit and the velocity became steady, say 200 + mph, you would have reached the point where engine thrust (Horse Power) would be exactly equal to the opposing aerodynamic drag and friction losses through the drive train. Then if there was a way to know the value of both drive train losses and aerodynamic drag, actual engine horse power could be calculated for that specific operating condition.

Very interesting

An 1983 Rx7 SoloII Driver

j9fd3s

the cat, catylises oxygen. they need to see the proper amount of oxygen in the exhaust to be happy. they want to see a 14.7:1 air fuel ratio. if you give it more oxygen it will get too hot and burn up. the cat is not bothered by a rich mixture, in fact they can use that to cool it off. misfires are also bad, misfires = more oxygen. so the way to keep the cat happy is to not get it super hot, and not have any misfires. and if you get it hot you can dump fuel in there and cool it down

i think this is right, ive been doing a lot of reading to try and find out how to make a cat live, so this is inferred from anywhere i could find info, which is scarce at best

mike

Buger

Great work so far Canzoomer. I believe the richer mixtures do lower the heat in the cats though. Liquid fuel lowers combustion temps by the condensing effect yes?

Brian

canzoomer

Yes, at certain levels.

The big problem is the newer emissions specs that say the car has to be running within spec in 5 minutes.

If we look at the rpm ranges over 6200 we see it running way too rich.
Same below 3750

In the mid range they are actually running it too lean, to heat up the cats.

The thing about the stock fuel maps that really surprised me was this midrange lean setting.

Going in we expected to see overly rich mixtures. As a result we hoped to gain higher rpm power.
When we discovered that the midrange was low, and we actually gained about 12 to 15 hp in there as well by enrichment it surprised us a lot!

In this they are likely leaning that range to ensure heating within 5 minutes to meet the testing requirements.

Anyway, no testing again until Monday. Burned out my coil packs on ignition testing.
Turned out that the Mazda coil packs are designed for a VERY short dwell and charge time. We were running them too long duration, and they melted!

Before they did we saw some interesting things. Pulled like a train. We were doiing our dyno runs in 3rd gear up to then, but we had to switch to 4th as we were actually running up the revs too fast to be easily controlled, and needed a higher gear to make the dyno tests less touchy. We were actually breaking the tires free in 3rd!

We are up an additional 12HP by raising the timing 1.5 to 2 degrees at 6200rpm and up. We are avoiding adding advance below 5,000 as that is the range you would risk knocking.
Although with the enrichment we added in the midrange it is still pretty unlikely..

That is 45+HP gained at 8000rpm, and most interestingly up 32HP at 5700, which is roughly the torque peak point. Torque was up 26 ft/lbs as well at 5700.

Out of all this we see:
Fuel controller alone will get us back the power we are missing.
In doing so we are still at levels to be legal in 48 states and Canada

With an ignition controller (I ordered in one with tunable charge and dwell timings!) we should be able to safely pull around 220-225HP at the wheels, which is probably around 260+ HP at the crank.

BTW, coil packs cost about $95 Canadian each.
sigh..

canzoomer

No ignorance. A very good question.
The gain of ram air effect is pretty well wasted with the stock intake and exhaust. We did some road runs as well as dynos early this week, and we saw little difference between the two.

We have been using a pressure sensor inserted in the intake and in the later stages of the exhaust, and were interested in this as my next step after the engine tuning may be intake and exhaust.
I think the stock intake system is pretty well matched to the stock exhaust system.

What we saw was that intake pressure DID increase quite a bit at about 100kmh. Power did not go up. This tells me that there is a flow restriction. Probably mainly in the exhaust.

I have not done anything yet about it, but next tests on that would be things like removing the air filter, removing the rear exhaust section, and testing on the dyno and road.
By doing that we can easily guage what gains (If any) we could expect with better exhaust and intake systems. I am really doubting we will see too much change with just the intake though. Speaking bluntly, most people think a car is running faster when they hear intake howl. Often however the change in power is minimal. It usually takes both intake AND exhaust to make a real difference. Good news here is that there is tons of room at the rear to install a good free flowing exhaust system.
I am thinking some mandrel bent pipe and a pair of long Magnaflows will likely do the trick. Maybe remove the stock resonator and put in a longer one as well to keep the sound levels down..

Digisan

:D

You are one crazy Canadian! This is quite exciting, I wonder what the remapped ECU plus an exhuast and intake would do?

canzoomer

I don't know until we try it, but the "seat of my pants" says I think we can hit 240HP at the wheels if we do it right.
While it won't be a Mustang Cobra killer, it will surprise a few people with 350Z's and so on..

I doubt we can break too far into the "280HP Club" unless we look at going beyond naturally aspirated.

Let's start the whole "Turbo versus Supercharger" debate off with a bang.
I think that a blower is a natural for the RX-8. There is very little room to cram a turbo in to the exhaust, but a blower would just drop right in place in front of the engine. And the nice thing is that it is an easy "bolt in" mod which could be removed for dealer service and warranty issues. Remember, with our "free" warranty services we will want to do any mods in an easily removed manner!
With a 10:1 compression ratio we would not want a lot of boost, but about 4 to 6 lbs would do lots for low and midrange, and probably put us to 300HP quite easily. Then you won't get sand kicked in your face by those nasty RX-7 3rd Gen owners!

RobDickinson

Heh, I doubt 300bhp in an rx-8 will trouble a 280bhp rX-7 but its better than nothing

Keep up the good work, even though I'm way to far away to benifit directly!