Official word from Mazda on dyno'ing RX-8
09-28-2003, 08:35 PM
#76
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and the wideband O2's on the dynojet measure post cat readings.
Your engine ecu primarily relies on the pre-cat readings.
I should have readings from a pre-cat wideband O2 setup (with data logging to a laptop) in a few days. We'll all see just how rich these cars are running.
Your engine ecu primarily relies on the pre-cat readings.
I should have readings from a pre-cat wideband O2 setup (with data logging to a laptop) in a few days. We'll all see just how rich these cars are running.
09-28-2003, 08:44 PM
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Originally posted by syntrix
and the wideband O2's on the dynojet measure post cat readings.
Your engine ecu primarily relies on the pre-cat readings.
I should have readings from a pre-cat wideband O2 setup (with data logging to a laptop) in a few days. We'll all see just how rich these cars are running.
and the wideband O2's on the dynojet measure post cat readings.
Your engine ecu primarily relies on the pre-cat readings.
I should have readings from a pre-cat wideband O2 setup (with data logging to a laptop) in a few days. We'll all see just how rich these cars are running.
Nahsua
09-28-2003, 10:15 PM
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Originally posted by NashuaCLS
True, But any OBD-2 scanner will read the O2 sensor voltage. If this is not enough as you mentioned replace the ore-cat stock O2 sensor with a Wideband O2 sensor and have the voltage read and ploted.
Nahsua
True, But any OBD-2 scanner will read the O2 sensor voltage. If this is not enough as you mentioned replace the ore-cat stock O2 sensor with a Wideband O2 sensor and have the voltage read and ploted.
Nahsua
It's a whole new O2 outside of any factory O2, with a digital reader.
This is not an autometer gauge tapped into the factory O2, not obd2 readings.
It's a true wideband that is going to be welded into the stock pipe before the cat., with some electronics that read the values (not a gauge).
09-28-2003, 10:18 PM
#80
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Originally posted by syntrix
and the wideband O2's on the dynojet measure post cat readings.
Your engine ecu primarily relies on the pre-cat readings.
I should have readings from a pre-cat wideband O2 setup (with data logging to a laptop) in a few days. We'll all see just how rich these cars are running.
and the wideband O2's on the dynojet measure post cat readings.
Your engine ecu primarily relies on the pre-cat readings.
I should have readings from a pre-cat wideband O2 setup (with data logging to a laptop) in a few days. We'll all see just how rich these cars are running.
It is quite rich.
09-29-2003, 08:36 AM
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Originally posted by bureau13
You're just playing dumb right? You don't really think if new rules were set up that expressly allowed this configuration, people would be racing to use them do you?
jds
You're just playing dumb right? You don't really think if new rules were set up that expressly allowed this configuration, people would be racing to use them do you?
jds
Yeah, this is not the case with the RX-8 and this is one of the reasons why I've been racing Miatas for years, but anyway, just echoing what Tresch was saying about being open minded. Go back to your regularly scheduled issues about apparent missing power and lousy explanations from Mazda people.
09-29-2003, 10:42 PM
#84
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Testing continues
So, having gone over NEARLY EVERY fricking device in the RX-8 shop manual and wiring manual, and having digitally metered most of them , we can now say:
1) There is no accelerometer in the car
2) There IS a barometric pressure sensor.
3) The ABS and DSC may be completely disabled by removing the fuse #12 on the fuse block.
This is a 60A fuse, B/L color code.
4) There are 4 wheel speed sensors, used for ABS and DSC.
Removing the fuse not only disables the ABS/DSC and wheel sensors, but also disables the circuit to the ECU.
The ECU throws no fault code when this is disabled.
The ECU does not change fuel or ignition output modes under slippage or varying wheel speed conditions when this is disabled.
One may easily leave these systems on, and using a programmable pulse generator feed in a false signal on the front wheel sensor harness plugs. This also does not affect ECU readings, fuel or ignition outputs.
The DSC off switch takes the DSC off the ECU circuit when pushed once.
It is not necessary to hold and disable the switch. While this does disable it, this is for safety purposes only. It stops the DSC from working until the ignition is switched off, whereas the single short push works in the same fashion, but allows it to be turned back on again. There is no functional difference between thetwo states, except that in the "long hold" mode it can not be turned back on again.
There are only 2 only conditions that can provide feedback to the ECU, when used in conjunction with the DSC and the wheel sensors, that would possibly affect the DSC and cause it to reduce power:
One is the steering angle sensor, which is not activated until we pass about 40% ( or more) turn in either direction.
IF we achieve 40% or more turn, and IF the DSC is enabled, then a signal is sent to the ECU.
The other is the rear wheels. When they turn in substantially unequal amounts ( wheelspin), then the DSC sends a signal to the ECU, which will reduce the power output.
It also looks for front wheels being turned, and if so can reduce power output.
If the wheels are turned more than 40%, and if the rear wheels turn at greatly unequal rates, then the ECU will adjust the ignition and fuel to reduce power output. When the rear wheels resume turning at the same rate, then the DSC signals it is back to normal, and the ECU returns the ignition and fuel to normal states for the throttle level and rpm range.
There is no correlation whatsoever with the front wheel speed sensors and the DSC. They only work with the ABS system.
There is a wheel turn sensor which will trigger the ECU to reduce power if the rear wheels slip unequally. It will reduce even more if the front wheels are turned a lot.
So, if you want to dyno an RX-8, feel free to keep the DSC on, or off, as you wish. Just do NOT turn the wheels, and do not spin the rear wheels on the rollers.
To be absolutely sure , you may remove the fuse for the ABS and ECU circuits, and then the sensors are absolutely inert. The car drives normally, just with no ABS or DSC.
So, Bern: I am calling "BS" buddy!
6) For those who have the headlight washer system, and want to disable it, it is motor driven, and the fuse is on a 20A fuse, #19 in the fuse box.
7) For those hooking up the rear low fog light, it is a 10A fuse #20 in the fusebox.
8) For those with Xenon HID headlights, the auto-leveling system is active, not just gravity driven, and has a front and rear leveling sensor, and two powered actuators, one for each headlight.
9) For the front fog lights, if one wants to make them work without the low beam being on, but with the park lights on, one needs to move one wire which comes from the foglight switch, and bypass the headlight relay.
The connection on this can be accessed at the fuse box.
The front fog light relay is module # E5-01
10) Tuning for power and economy:
Apart from the usual mass-air sensor, the RX-8 incorporates a barometric pressure sensor. Adjusting the output from it to the ECU has a significant effect on ignition timing and fuel injector flow rates as regulated by the ECU. I suspect that running at low baro and low humidity can make a significant difference in power output. At a GUESS maybe 10hp. Running a high baro pressure, at or below sea level, with high humidity, will result in more power output.
There is also a standard anti-knock sensor. When it is triggered the ignition is retarded by about 2 degrees. on the leading plugs, but nothing on the trailing plugs.
This has surprisingly little effect on the power output. I guiess that due to the dual spark plug setup the burn does not change much from this. It also means that running lower octane fuel should have little effect on power, but will have an effect on fuel economy.
More to come. If anyone has specific wiring and logic/sensor questions, fire away!
1) There is no accelerometer in the car
2) There IS a barometric pressure sensor.
3) The ABS and DSC may be completely disabled by removing the fuse #12 on the fuse block.
This is a 60A fuse, B/L color code.
4) There are 4 wheel speed sensors, used for ABS and DSC.
Removing the fuse not only disables the ABS/DSC and wheel sensors, but also disables the circuit to the ECU.
The ECU throws no fault code when this is disabled.
The ECU does not change fuel or ignition output modes under slippage or varying wheel speed conditions when this is disabled.
One may easily leave these systems on, and using a programmable pulse generator feed in a false signal on the front wheel sensor harness plugs. This also does not affect ECU readings, fuel or ignition outputs.
The DSC off switch takes the DSC off the ECU circuit when pushed once.
It is not necessary to hold and disable the switch. While this does disable it, this is for safety purposes only. It stops the DSC from working until the ignition is switched off, whereas the single short push works in the same fashion, but allows it to be turned back on again. There is no functional difference between thetwo states, except that in the "long hold" mode it can not be turned back on again.
There are only 2 only conditions that can provide feedback to the ECU, when used in conjunction with the DSC and the wheel sensors, that would possibly affect the DSC and cause it to reduce power:
One is the steering angle sensor, which is not activated until we pass about 40% ( or more) turn in either direction.
IF we achieve 40% or more turn, and IF the DSC is enabled, then a signal is sent to the ECU.
The other is the rear wheels. When they turn in substantially unequal amounts ( wheelspin), then the DSC sends a signal to the ECU, which will reduce the power output.
It also looks for front wheels being turned, and if so can reduce power output.
If the wheels are turned more than 40%, and if the rear wheels turn at greatly unequal rates, then the ECU will adjust the ignition and fuel to reduce power output. When the rear wheels resume turning at the same rate, then the DSC signals it is back to normal, and the ECU returns the ignition and fuel to normal states for the throttle level and rpm range.
There is no correlation whatsoever with the front wheel speed sensors and the DSC. They only work with the ABS system.
There is a wheel turn sensor which will trigger the ECU to reduce power if the rear wheels slip unequally. It will reduce even more if the front wheels are turned a lot.
So, if you want to dyno an RX-8, feel free to keep the DSC on, or off, as you wish. Just do NOT turn the wheels, and do not spin the rear wheels on the rollers.
To be absolutely sure , you may remove the fuse for the ABS and ECU circuits, and then the sensors are absolutely inert. The car drives normally, just with no ABS or DSC.
So, Bern: I am calling "BS" buddy!
6) For those who have the headlight washer system, and want to disable it, it is motor driven, and the fuse is on a 20A fuse, #19 in the fuse box.
7) For those hooking up the rear low fog light, it is a 10A fuse #20 in the fusebox.
8) For those with Xenon HID headlights, the auto-leveling system is active, not just gravity driven, and has a front and rear leveling sensor, and two powered actuators, one for each headlight.
9) For the front fog lights, if one wants to make them work without the low beam being on, but with the park lights on, one needs to move one wire which comes from the foglight switch, and bypass the headlight relay.
The connection on this can be accessed at the fuse box.
The front fog light relay is module # E5-01
10) Tuning for power and economy:
Apart from the usual mass-air sensor, the RX-8 incorporates a barometric pressure sensor. Adjusting the output from it to the ECU has a significant effect on ignition timing and fuel injector flow rates as regulated by the ECU. I suspect that running at low baro and low humidity can make a significant difference in power output. At a GUESS maybe 10hp. Running a high baro pressure, at or below sea level, with high humidity, will result in more power output.
There is also a standard anti-knock sensor. When it is triggered the ignition is retarded by about 2 degrees. on the leading plugs, but nothing on the trailing plugs.
This has surprisingly little effect on the power output. I guiess that due to the dual spark plug setup the burn does not change much from this. It also means that running lower octane fuel should have little effect on power, but will have an effect on fuel economy.
More to come. If anyone has specific wiring and logic/sensor questions, fire away!
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09-30-2003, 01:05 AM
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It sounds to me like what he's saying is if you aren't cranking over the steering wheel while on the dyno (and why would you?) it should be reading properly whether you pull the fuse or not...right? Did I misread something? I'd love to be corrected, because frankly I find this a little disturbing.
jds
jds
Originally posted by SuperRex
great info canzoomer, so if someone were to completely disable abs and dsc by pulling a fuse, a dyno would read the hp properly correct?
great info canzoomer, so if someone were to completely disable abs and dsc by pulling a fuse, a dyno would read the hp properly correct?
09-30-2003, 08:36 AM
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Originally posted by bureau13
It sounds to me like what he's saying is if you aren't cranking over the steering wheel while on the dyno (and why would you?) it should be reading properly whether you pull the fuse or not...right? Did I misread something? I'd love to be corrected, because frankly I find this a little disturbing.
jds
It sounds to me like what he's saying is if you aren't cranking over the steering wheel while on the dyno (and why would you?) it should be reading properly whether you pull the fuse or not...right? Did I misread something? I'd love to be corrected, because frankly I find this a little disturbing.
jds
Yep, it pretty much says unless the wheel is cranked over or the wheels are slipping on the dyno rollers, it should read correctly. Which means Mazda is still not telling the whole story. It's starting to look like all those who were suspicious of the technobabble in that unofficial official Mazda explanation may be correct in feeling that way.
09-30-2003, 09:03 AM
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Great info Canzoomer -- from a real world perspective I must say that the car acts very differently with the DSC totally disabled (hold button down) versus just clicked off. The DSC will definitely grab the back end when on. With it clicked off -- I get good wheel spin to a point and then the system will kick in. With it disabled you can do some really crazy things. :D Based on your info this doesn't seem to make sense. You are saying there shouldn't be any difference between click off and totally disabled 
09-30-2003, 09:24 AM
#90
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Originally posted by RXhusker
Great info Canzoomer -- from a real world perspective I must say that the car acts very differently with the DSC totally disabled (hold button down) versus just clicked off. The DSC will definitely grab the back end when on. With it clicked off -- I get good wheel spin to a point and then the system will kick in. With it disabled you can do some really crazy things. :D Based on your info this doesn't seem to make sense. You are saying there shouldn't be any difference between click off and totally disabled
Great info Canzoomer -- from a real world perspective I must say that the car acts very differently with the DSC totally disabled (hold button down) versus just clicked off. The DSC will definitely grab the back end when on. With it clicked off -- I get good wheel spin to a point and then the system will kick in. With it disabled you can do some really crazy things. :D Based on your info this doesn't seem to make sense. You are saying there shouldn't be any difference between click off and totally disabled
Wheelspin at the rear wheels is the key. The DSC detects wheelspin, and it then tells the ECU. The ECU cuts power.
If the DSC is off then the ECU does nothing about it.
The difference in performance you see is when the ECU cuts power, it does not turn it back up again instantly. It waits a while.
So, on a hard launch, if you spin a tire for a moment, then it takes about 3 seconds to return to full power.
As for differences in the 2 modes, I don't meant to be critical, but I suggest it is psychological.
WRT the turned wheels, if wheelspin is detected, the ECU will not return full power until the wheels are straightened.
09-30-2003, 09:33 AM
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Originally posted by RXhusker
You are saying there shouldn't be any difference between click off and totally disabled
You are saying there shouldn't be any difference between click off and totally disabled
09-30-2003, 09:50 AM
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Originally posted by javahut
And why would an additional icon light up on the display (the little swerving car with skid marks), after holding DSC in versus just pressing once, if there was no functional difference between the two?
And why would an additional icon light up on the display (the little swerving car with skid marks), after holding DSC in versus just pressing once, if there was no functional difference between the two?
If you believe your DSC is faulty, you can switch it off permanently until you restart the car (this is the best example that comes to mind.) - Most likely this might be done by a technician while performing some sort of diagnostic on the car or system. My guess..
09-30-2003, 10:00 AM
#94
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Originally posted by javahut
And why would an additional icon light up on the display (the little swerving car with skid marks), after holding DSC in versus just pressing once, if there was no functional difference between the two?
And why would an additional icon light up on the display (the little swerving car with skid marks), after holding DSC in versus just pressing once, if there was no functional difference between the two?
Press the button briefly and the one light goes on, and DSC is disabled.
If you want to turn it back on press the button AGAIN.
Press and hold for over 5 seconds and it is turned off until you re-start the car.
09-30-2003, 10:12 AM
#95
Originally posted by canzoomer
Maybe I did not express it clearly enough:
Press the button briefly and the one light goes on, and DSC is disabled.
If you want to turn it back on press the button AGAIN.
Press and hold for over 5 seconds and it is turned off until you re-start the car.
Maybe I did not express it clearly enough:
Press the button briefly and the one light goes on, and DSC is disabled.
If you want to turn it back on press the button AGAIN.
Press and hold for over 5 seconds and it is turned off until you re-start the car.
09-30-2003, 10:15 AM
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Uh... yeah... I got that. So you're saying they have an icon on the display and the only thing it is signifying is that I can no longer re-enable DSC until I turn the car off and back on?
09-30-2003, 10:18 AM
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Originally posted by RobDickinson
Not just that, but the DSC will come back online if the ABS kicks in (I assume just for the ABS time?) - only way to stop it is a long press.
Not just that, but the DSC will come back online if the ABS kicks in (I assume just for the ABS time?) - only way to stop it is a long press.
09-30-2003, 11:23 AM
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Hey Canzoomer,
While your pouring through the logic of this car can you take a moment to look at the tire pressure sensor circuit? I would really like to know how to disable it for the times when I am using wheels without sensors. Thanks and keep up the good work!
While your pouring through the logic of this car can you take a moment to look at the tire pressure sensor circuit? I would really like to know how to disable it for the times when I am using wheels without sensors. Thanks and keep up the good work!
09-30-2003, 04:41 PM
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Canzoomer: It only takes one fault to go into safe mode. I appreciate you going through the motions of checking the traction system, but that is only one that we know of could be triggered to make it run rich on the dyno.
I'm calling your BS flag, and raising you a Exhaust Temp sensor.
--dan
I'm calling your BS flag, and raising you a Exhaust Temp sensor.
--dan
09-30-2003, 05:45 PM
#100
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Originally posted by canzoomer
Maybe I did not express it clearly enough:
Press the button briefly and the one light goes on, and DSC is disabled.
If you want to turn it back on press the button AGAIN.
Press and hold for over 5 seconds and it is turned off until you re-start the car.
Maybe I did not express it clearly enough:
Press the button briefly and the one light goes on, and DSC is disabled.
If you want to turn it back on press the button AGAIN.
Press and hold for over 5 seconds and it is turned off until you re-start the car.
- the quick push disabled the DSC stability control system, with it's own indicator light. Another quick push re-enables DSC.
- The long push additionally disabled the separate traction control system, with it's separate traction control indicator light (the car with two rubber streaks behind it). DSC and TC can not be re-enabled without cycling the ignition of the vehicle.
Thoughts on TC separate from DSC?
Thanks,
Gordon