Slow Speeds with OBDLink MX BT

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aaronc7
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Slow Speeds with OBDLink MX BT

Post by aaronc7 »

I've read through a bunch of other threads on this sort of subject on here, but I have not been able to make any progress on my setup.

HLT Grand Prix (latest version as of 11/8/15)
LG G2 on android 5.0.2
2003 Corvette Z06
OBDLink MX Bluetooth

All I want from OBD data is RPM, VSS, TPS at the highest possible logging rate that I can get. I understand it's an older car/ECU, so I'm not going to get amazing results. I've played around with other apps as well (TrackAddict in particular), and logging only those 3 PIDs I get a 5.0-5.5 Hz rate. With HLT I am only getting around 2 Hz, so I feel like there must be some issues going on behind the scenes. Overall I really like the functionality and features of HLT, this is the last hurdle I am trying to overcome. I find 5 Hz to just sufficient... if I can reach that, I will be happy.

Initially I had disconnect issues, but I have seemed to have fixed that by selecting the protocol manually (SAE J1850 VPW 10.4 kbps) in the expert settings. I have tried excluding all unwanted PIDs and refresh rate did improve slightly.... but only to the 2 Hz that I mentioned previously.

Looking for some tips or guidance from here. Thank you in advance.

-Aaron

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Harry
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Re: Slow Speeds with OBDLink MX BT

Post by Harry »

That's probably comparing apples with oranges ;-)

When counting update rates, there are several options. You can count the rate of individual PIDs (which is what most apps will do) and the rate full fixes (sets of PIDs) coming in. As the former is a rather technical measure and not too useful except when doing IT performance tuning, LapTimer uses the later when displaying update rates. Pre CAN busses will typically deliver 1 or 2 Hz in LapTimer's rate measurement, which means between 5 an 10 PIDs with standard settings in average. So in case you see a 2, you actually get a technical update rate of 10 Hz (which is a lot for pre CAN cars). Looking into the second snapshot above, you can see raw/brutto/netto/requests and 6/1/1/6. This means you get PIDs at 6 Hz, mapped to 1 Hz for complete PID sets (brutto and netto - which should be gross / net in English...). As LapTimer needs to request PIDs individually for non CAN busses, the request rate is the same as the raw rate.

LapTimer received lots of performance tuning to achieve high OBD rates over the years. I doubt you will see any app getting faster rates, most will be inferior. All known technics to improve rates using ELM adapters have been deployed.

Or the other way around: in case the rate shown in LapTimer is 2 Hz from time to time, you are fine.

- Harry

P.S. Touch any update rate gadget in LapTimer and you will toggle the display between gross, gross at high precision and raw rates.
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aaronc7
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Re: Slow Speeds with OBDLink MX BT

Post by aaronc7 »

Thanks for the quick response!

Only reason I really referenced those numbers was because it seemed to correlate to the behavior I was seeing. I won't get hung up on the numbers or 5 Hz, etc.... but I still believe there is a big issue going on with HLT and my OBD2 data. Sometimes I feel like it's not just slow, but even out of sync with HLT, so maybe some sort of larger communication issue going on?

I made a few back to back comparison videos/logs to show what I am talking about. In this scenario I just fired the car up in the garage and do a couple engine revs to ~2000 and then a few more to 3000-3500. Only really valid data points for comparison for this is engine RPM and TPS. I also set the phone up in this spot so you can see the revs climb on the HUD.

To help HLT logging rate in anyway I could, I excluded the following PIDs for this test/comparison: 0105 ECT, 010B MAP, 010F IAT, 0110 MAF. I saw in other threads that these PIDs are not polled that often and should not have a big impact on logging rate, but I wanted to do whatever I could to improve it. Within the other logging app, I had RPM, TPS and VSS selected.

HLT with built in overlay rendered:
https://www.youtube.com/watch?v=4TWvoIUXS6s

HLT using RaceRender to overlay (only field I added was a THROTTLE * 100 field so RaceRender would see it as a 0 min to 100 max value):
https://www.youtube.com/watch?v=ym9RdDwZ_x8

TA using RaceRender to overlay:
https://www.youtube.com/watch?v=GXcxxl7lJrk
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Harry
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Slow Speeds with OBDLink MX BT

Post by Harry »

LapTimer stores data at GPS rate. So please watch your GPS reception when recording. Overlays are interpolated to 30 Hz again, but a rate of 1 or below 1 in the workshop will degrade overlay quality. Real time display does not depend on GPS rate.

In case you want to keep all data, please consider a 5 or 10 Hz GPS. This is usually the first option to add.

Harry
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aaronc7
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Re: Slow Speeds with OBDLink MX BT

Post by aaronc7 »

I have a XGPS160 and used it for all videos/logs above. It was sitting on the trunk and had good signal. The csv data log confirms the 10 Hz log rate.
Last edited by aaronc7 on Mon Nov 09, 2015 12:30 am, edited 1 time in total.
aaronc7
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Re: Slow Speeds with OBDLink MX BT

Post by aaronc7 »

Cell phone fail, let me finish my last reply.

I ran the app with the OBDLink connected to our 2013 Toyota Tacoma and 2015 Hyundai Santa Fe Sport. Both cases the obd rate was 2 Hz. Potential issue with this phone? LG G2.

Unless you have any other ideas I will probably just run HLT + xgps160 and log obd separate via my EFILive handheld logger/tuner. Slight inconvenience syncing 3 files but not the end of the world.
aaronc7
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Re: Slow Speeds with OBDLink MX BT

Post by aaronc7 »

Update.

I had pretty much given up hope with HLT and OBD logging, but I saw the last update on Android mentioned something about bluetooth in the "what's new" section, so I decided to try again. I did not change anything, same hardware etc.... I am now getting update rate of 6 Hz and a total PID rate of 25+ PID/s. About 4x faster and definitely usable now.
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Slow Speeds with OBDLink MX BT

Post by Harry »

The new version has Bluetooth Low Energy discovery disabled by default. For your accessory combination you don't need this feature anyway... Looks like this is a weak implementation of the Bluetooth stack of specific Android models...

Thanks for letting me know, I will try to find a solution allowing BT LE without having this negative impact on standard BT connections...

Harry
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Re: Slow Speeds with OBDLink MX BT

Post by aaronc7 »

No problem! I tested this on my 2013 Toyota Tacoma and am seeing 4x the PID/s rate also, post update. Right around 50 PID/s on that one.
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