No fuel level reading on Mazda RX-8, speed in hundredths.

Discussion and research on OBDII integration, especially on OEM specific PIDs from Ford, GM, Chevrolet, BMW, Porsche, Audi, Toyota, Volkswagen, Mazda, Honda, Subaru, Mitsubishi and others.
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Dadspeed
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Joined: Sun Mar 18, 2018 3:56 am
Location: Champaign, IL

No fuel level reading on Mazda RX-8, speed in hundredths.

Post by Dadspeed »

Hi!

I just got my Pro Mk3 installed in the car and I have my first time trial event with it this weekend. I'm able to get some OBD PIDs to work, but fuel level shows as 0. If I plug the stock gauges back in (I am planning on replacing them with the tablet), I see a fuel level on the gauge. Any suggestions?

Also, the speed reads to the second decimal place. That's far more accuracy than I need, and I find it a bit distracting. I don't see an option for the display to change that. Again, any advice would be appreciated.

Thank you very much!

Nick
TT5 Mazda RX-8

brentp
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Post by brentp »

Hi,

It's possible that your car does not report fuel level over OBDII - it's part of the SAE standard, but cars are not required to report support all OBDII PIDs. An alternative is to wire in one of the RaceCapture/Pro analog inputs right into the fuel sender line that comes from the gauges.

The data is natively in that level of precision; one of the features we have coming up is to allow you to specify locally for that gauge how you want it to display.

Thanks,
Brent Picasso
CEO and Founder, Autosport Labs
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Dadspeed
Posts: 14
Joined: Sun Mar 18, 2018 3:56 am
Location: Champaign, IL

Post by Dadspeed »

Hi, Brent,

Thanks for your reply. I'm certainly no OBD/CAN expert, but I'll tell you what I've seen in the past from the RX8's ECU. I have used Harry's Lap Timer and, with an OBDII connection, I have seen my fuel level in that app. Even better, I saw it in real time, so I could see it slosh in the tank. That's handy for avoiding fuel starve.

I don't know how that app logged that data. Was it CAN? Was it OBDII?

I did just try adding the fuel level CAN channel on the RaceCapture app, but that didn't seem to work. When I add that and remove the OBDII fuel level channel, I don't get a fuel level option in the dashboard.

Any advice you can offer would be greatly appreciated.

Thanks,
Nick
TT5 Mazda RX-8

Dadspeed
Posts: 14
Joined: Sun Mar 18, 2018 3:56 am
Location: Champaign, IL

Post by Dadspeed »

Okay, I got it to work - largely by bumbling around the interface. Here's what I did:

I looked up the OBDII PID on Wikipedia, and checked to make sure the channel was mapped correctly to it. It was, but then I looked at the matching CAN ID, inside the OBDII channel settings in RaceCapture. It was 2024. When I looked at the CAN ID inside the CAN channel settings for fuel level, it was 0. I set it to 2024 instead, and the fuel level displays correctly.

Woohoo!
TT5 Mazda RX-8

Dadspeed
Posts: 14
Joined: Sun Mar 18, 2018 3:56 am
Location: Champaign, IL

Post by Dadspeed »

When I got to the track Saturday, this stopped working. It no longer displays fuel level. Hurgh...
TT5 Mazda RX-8

brentp
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Post by brentp »

Hi, thanks for the followup. Is it still not showing fuel level, or are you seeing it happen intermittently?

What year is your RX8? Are you using the CAN OBDII cable, or the OBDII legacy adapter?

Thanks,
Brent Picasso
CEO and Founder, Autosport Labs
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Dadspeed
Posts: 14
Joined: Sun Mar 18, 2018 3:56 am
Location: Champaign, IL

Post by Dadspeed »

The car is a 2004 Mazda RX8. I'm using the Molex connector that came with the Mk3, and I've spliced it to the CAN high/low wires from the car. So all I have connected to the Mk3 is power, ground and CAN high/low.

Since getting the fuel level to work that one time, it doesn't appear to have worked again.

Thanks,
Nick
TT5 Mazda RX-8

brentp
Site Admin
Posts: 6281
Joined: Wed Jan 24, 2007 6:36 am

Post by brentp »

Hi,

Thanks for the update. Can you post your configuration so we can check it out?
Brent Picasso
CEO and Founder, Autosport Labs
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Dadspeed
Posts: 14
Joined: Sun Mar 18, 2018 3:56 am
Location: Champaign, IL

Post by Dadspeed »

I take it that's a config file that can be saved out. I'll take a look when I get home tonight.

Thanks!
TT5 Mazda RX-8

Dadspeed
Posts: 14
Joined: Sun Mar 18, 2018 3:56 am
Location: Champaign, IL

Post by Dadspeed »

Now that I understand that I need to set the PIDs I track to 'passive mode', I can get the RaceCapture to read the fuel level. But it's quite wrong. My OBDII scanner says 24%, and the RaceCapture says 4%. So I guess I have some learning to do.
TT5 Mazda RX-8

brentp
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Post by brentp »

Hi, are you running two OBDII devices at the same time on your OBDII connection? OBDII passive mode in RaceCapture is designed to let another OBDII device "request" the data, and RaceCapture just listens for the response.
Brent Picasso
CEO and Founder, Autosport Labs
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Dadspeed
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Joined: Sun Mar 18, 2018 3:56 am
Location: Champaign, IL

Post by Dadspeed »

I only have another OBDII scanner connected for debugging purposes.

I started using 'passive mode' because, without it, I see all kinds of craziness in the OBDII PIDs on my scanner.
TT5 Mazda RX-8

brentp
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Post by brentp »

Got it. thanks for clarifying.
Brent Picasso
CEO and Founder, Autosport Labs
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Dadspeed
Posts: 14
Joined: Sun Mar 18, 2018 3:56 am
Location: Champaign, IL

Post by Dadspeed »

I'm still having issues getting OBDII to work. If I try to read even a single OBDII PID, my car can't rev past 8k rpm. It looks to me like reading OBDII PIDs causes my Pro/Mk3 to interfere with my ECU.

I have my Mk3 reading engine speed via CAN, and I have gauges for some other critical measurements. But in order to read fuel level in between sessions I have to plug the stock dash in. I have no way to read fuel level while on track.

I would appreciate some help with this.

Thanks.
TT5 Mazda RX-8

brentp
Site Admin
Posts: 6281
Joined: Wed Jan 24, 2007 6:36 am

Post by brentp »

Hi, apologies for the delay. We have a task to review some information you sent over email; we'll take a look at that this evening!

Thanks,
Brent Picasso
CEO and Founder, Autosport Labs
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