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So while I wait for all my turbo parts to arrive, the one thing that has been bugging me is the fact that I need an AFR and Boost gauge, but there is just no good looking way to mount them.
So I decided the best looking solution would be for the gauges to be on the pretty red LCD right above the head unit. Of course when I called mazda & their suppliers, no one would give me the signaling spec for the display, so I had to reverse-engineer it. Using a logic analyzer I figured it all out. Here are some pics of this process: http://i.imgur.com/YBhi8.jpg http://i.imgur.com/hQGSm.jpg
Step 2 was to design a circuit board that could fit in a small enclosure. I decided the best place was the ashtray. I figured since the CAN bus isn't too far from there, there is nothing preventing me from querying the car's computer for sensor data as well.
Here is the final product, I am calling it the GOODbox (Gauges On the OEM Display):
When on, it overrides the data coming from the head unit and shows you live gauge data. I can even override the fonts and make custom patterns & symbols. There is also a buzzer/beeper to warn about overboost, and while I was at it I added a feature that lets you choose custom startup text instead of the stock "mazda rx-8"
It can display 2 different screens, A or B. Each screen can show either 1 or 2 gauges. This way you can quickly switch around up to4 different gauges. It has a menu system that lets you choose gauges, calibrate the boost gauge and edit the custom startup text. Since the display is 12 characters, each gauge gets 6 characters in dual mode. Sometimes that is kind of cramped, but oh well. There is probably some improvements I could make with the formatting of dual gauge mode.
The harness just connects to tap splice connectors on the LCD's cable, a 12V power source and the CAN bus which is closest just above the head unit by the Tire Pressure Sensor Module.
List of currently supported sensor data:
Boost pressure
Coolant Temp
Air/fuel ratio
Intake Air temp
Short term fuel trim
Long term fuel trim
Throttle position
Engine load (in %)
Speed (mph)
Engine RPM
I can add anything to this list that the RX8's computer supports, just have to know the right ID.
A couple of features I would like to add soon:
When I designed the board, I added an additional analog pad that you could solder your own custom sensor to (for example EGT), but I haven't yet added that feature in the firmware. The idea is that you would use the menu to give it a name, and set calibration multiplier, divisor and offset. So displayed value would be data*multiplier/divisor+offset.
The display for the Mazda3 and Mazda6 is the same as the one in the RX8, so there is no reason it wouldn't work for those cars too. The MS3 definitely needs a nice boost gauge like this.
Well, what do you think? I am thinking about selling these. I would love to hear some feedback, and refine it a bit more. Soldering on all the small parts is kind of a pain, so I might have to find some kind of manufacturer to assemble the PCB for me.
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all i can say is wow! will this be something you will be able to provide and offer to us?
Yes that is the plan. I got to figure out how to make many of them without having to slave over a soldering iron all week, and set a price. Also got to write up an install guide and manual.
pieter: this is an amazing project, I'm quite impressed.
just a word of advice: don't mention any prices or the mods will close the thread since you haven't applied for a Group Buy yet. As long as you don't mention a price, you're all set. (read between the lines)
either way, definitely look into selling this.
if the price is fair, I'm sure you'll see demand.
pieter: this is an amazing project, I'm quite impressed.
just a word of advice: don't mention any prices or the mods will close the thread since you haven't applied for a Group Buy yet. As long as you don't mention a price, you're all set. (read between the lines)
either way, definitely look into selling this.
if the price is fair, I'm sure you'll see demand.
Cool, yeah I figured, hence no pricing. who do I email?
Location: Buddhist Monastery, High Himalaya Mtns. of Tibet
Posts: 11,621
Other than where it is displayed, how is this different than the Scanguage?
__________________ Don't try this at home. It could be dangerous. I have years of experience.
Emissions and fuel economy haven't exactly been areas of strength for past rotary power plants, but absolutely no one with a soul has ever cared. - Autoweek
Rotary History:1982 RX7 GS, 1985 RX7 GSL-SE, 2004 RX8 Sport-Continuous Rotary Owner since 1985
Racing History:SCCA Solo II 1979-1986, Skip Barber Comp School 1983, SCCA Club Racing 1987-1993, 2004-2011 Track Days
Enlightenment is man’s leaving his self-caused immaturity. Immaturity is the incapacity to use one's intelligence without the guidance of another. Such immaturity is self-caused if it is not caused by lack of intelligence, but by lack of determination and courage to use one's intelligence without being guided by another. Sapere Aude! - Immanuel Kant
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