[HOWTO] Debugging OBD Communication

Collection of all FAQs and HOW-TOs posted throughout the system. Read only.
froggy47
20 or more Posts ★★★
20 or more Posts ★★★
Posts: 129
Joined: Tue Feb 25, 2014 2:20 am

Re: [HOWTO] Debugging OBD Communication

Post by froggy47 »

Any help?

Thanks!
Autox & HPDE
2004 Corvette Z06
Moto X/android, Dual 160, generic OBD2
User avatar
Harry
Site Admin
Site Admin
Posts: 10518
Joined: Sun Sep 12, 2010 10:32 am
Location: Siegum, Germany
Contact:

Re: [HOWTO] Debugging OBD Communication

Post by Harry »

@froggy47,

I cannot provide more help than I did. For a non CAN bus car, update rates around 2 Hz are what you can get. There is not a lot one can do here. One option is to connect sensors directly and work around OBD completely, and the other one is to buy a new car :-) If there would be a known option to increase speed, I'd provide it anyway, so no, there are no hidden settings to improve the rate. Btw. if acceleration shows up with 10 Hz, it is too low and you likely changed another Expert Setting. Maybe you want to try to delete and reinstall the app to get rid of wrong settings.

- Harry
Image Image Image Image
gplracerx
20 or more Posts ★★★
20 or more Posts ★★★
Posts: 836
Joined: Thu May 03, 2012 5:26 am
Location: Kingsport, TN USA

Re: [HOWTO] Debugging OBD Communication

Post by gplracerx »

I'll second the 10Hz accelerometer update rate is too slow, especially for autocross. I set mine at the maximum, ~100Hz. Even 30 Hz ends up being over smoothed, in my opinion, as the cutoff frequency of the filter is directly proportional to the accelerometer update rate.

There's an option to reset expert settings to default at the bottom of the expert settings page. If I remember correctly, the default accelerometer update rate is 30Hz.
Last edited by gplracerx on Tue Mar 03, 2015 9:09 pm, edited 1 time in total.
User avatar
Harry
Site Admin
Site Admin
Posts: 10518
Joined: Sun Sep 12, 2010 10:32 am
Location: Siegum, Germany
Contact:

[HOWTO] Debugging OBD Communication

Post by Harry »

Yes, but this option does not cover all settings - it is not safe.
Image Image Image Image
gplracerx
20 or more Posts ★★★
20 or more Posts ★★★
Posts: 836
Joined: Thu May 03, 2012 5:26 am
Location: Kingsport, TN USA

Re: [HOWTO] Debugging OBD Communication

Post by gplracerx »

Harry wrote:Yes, but this option does not cover all settings - it is not safe.
Good to know.
froggy47
20 or more Posts ★★★
20 or more Posts ★★★
Posts: 129
Joined: Tue Feb 25, 2014 2:20 am

Re: [HOWTO] Debugging OBD Communication

Post by froggy47 »

gplracerx wrote:I'll second the 10Hz accelerometer update rate is too slow, especially for autocross. I set mine at the maximum, ~100Hz. Even 30 Hz ends up being over smoothed, in my opinion, as the cutoff frequency of the filter is directly proportional to the accelerometer update rate.

There's an option to reset expert settings to default at the bottom of the expert settings page. If I remember correctly, the default accelerometer update rate is 30Hz.
I never touched accelerometer settings, I would have no way of knowing what is good or not regarding these update speeds.

Unfortunately I am finding the app (HLT) only works on my car and my phone with extensive expert guidance & I thank you Harry as you are VERY responsive on the forum, really among the best I have every "worked with".

So far as the disconnects I still have, only with the obd dongle, should I just expect that random disconnects will always happen?

My previous question, is wifi obd2 mx better at staying connected and update speed? My android phone does wifi also.

Thanks.
Autox & HPDE
2004 Corvette Z06
Moto X/android, Dual 160, generic OBD2
User avatar
Harry
Site Admin
Site Admin
Posts: 10518
Joined: Sun Sep 12, 2010 10:32 am
Location: Siegum, Germany
Contact:

Re: [HOWTO] Debugging OBD Communication

Post by Harry »

Well, the good thing is most users do not experience that kind of issues :-) Both BT and WiFi connections can be disturbed - that's the nature of wireless connections. WiFi is more fragile in my experience, and more complicated to configure. But that's a my personal experience and not representative.

- Harry
Image Image Image Image
froggy47
20 or more Posts ★★★
20 or more Posts ★★★
Posts: 129
Joined: Tue Feb 25, 2014 2:20 am

Re: [HOWTO] Debugging OBD Communication

Post by froggy47 »

I tried the VGate obd2 BT dongle with good results, it "likes" the "special" settings that we ended up with while trouble shooting the connection issues with the ScanTool obd2 MX BT.

It paired & connected for 5 -6 min KOEO and then I started the engine and it stayed connected, not a blink.

Also Dual 160 stayed green the whole time.

For the accelerometer It was set to 10 (never touched by me) and I changed it to 20, then the Hz went from 9/10 to 18/19 so an improvement there. Should I change it higher? What will be the effect/benefit?

Posting all this so others who look at the thread will gain some info on obd trouble shooting.
Autox & HPDE
2004 Corvette Z06
Moto X/android, Dual 160, generic OBD2
gplracerx
20 or more Posts ★★★
20 or more Posts ★★★
Posts: 836
Joined: Thu May 03, 2012 5:26 am
Location: Kingsport, TN USA

Re: [HOWTO] Debugging OBD Communication

Post by gplracerx »

I set my accelerometer update rate to 100Hz. It shows up as 91Hz on the accelerometer display. At 20Hz, the filter time constant is too low for autocross, in my opinion. YMMV. If I get time, I'll put up some graphs to show the effect. I've got to prep the car for the Dixie National Tour event this weekend.
User avatar
Harry
Site Admin
Site Admin
Posts: 10518
Joined: Sun Sep 12, 2010 10:32 am
Location: Siegum, Germany
Contact:

Re: [HOWTO] Debugging OBD Communication

Post by Harry »

froggy47 wrote:For the accelerometer It was set to 10 (never touched by me) and I changed it to 20, then the Hz went from 9/10 to 18/19 so an improvement there. Should I change it higher? What will be the effect/benefit?
The default rate predefined in LapTimer is 30 Hz.

- Harry
Image Image Image Image
Post Reply