GPS speed logging app, anyone got any suggestions?

[GDCobra]

Hi all,
Not sure if thsi is the best subject for this but as it's related to some engine management work I'm doing I'll give it a go.

I'm currenlty looking for a phone app (IOS only unfortunately) to record and log my speed via GPS and allow me to upload the log to my PC, and ideally free as I'm a tight wad.

This is to allow me to have a speed reference with my ECU data.

The log only needs to contain speed and time (to within 1 sec I'd say) but if it also held GPS coordinates that would probably be advantageous, at some point.
Seems like this should be do-able, I already have a GPS speedo' but that doesn't do logging but there are other apps which log other data so that must be possible also.

Can anybody suggest a likely suspect?

[stevieturbo]

to record on the phone just ?

Plenty of lap timer type apps available

https://www.gps-laptimer.de/

https://play.google.com/store/apps/deta ... p&hl=en_GB

https://lifeatlean.com/cheap-lap-timer-setups/

[GDCobra]

to record on the phone just ?

Plenty of lap timer type apps available

https://www.gps-laptimer.de/

https://play.google.com/store/apps/deta ... p&hl=en_GB

https://lifeatlean.com/cheap-lap-timer-setups/

Thanks for the suggestions Steve. I'll check them out but not sure from the descriptions that they're what I'm looking for.

I am looking for a phone app as this is the only 'simple' way I have of recording GPS speed, also has to be iPhone as this is the only phone I have.
At a push I could run it on my Android table but that's an old OS so may be compatibility issues.
I don't really want anything complex or costly as this will really only be single use.
All I want it for is to calibrate the speed reading in my engine management system by comparing logs from the ECU with those from the app (so it needs the ability to send the log data to my PC) based on their timestamp. Once I've verified my calibration that will be job done so not needed thereafter.

[stevieturbo]

you hardly need to do that.

just drive along in a gear at say 3000rpm....then use gps to view your speed. Job done. Make any adjustments.

[GDCobra]

you hardly need to do that.

just drive along in a gear at say 3000rpm....then use gps to view your speed. Job done. Make any adjustments.

Well the RPM is irrelevent as the speed signal comes from the gearbox output. What you suggest is pretty much what I have been doing but it's a bit dodgy trying to read 2 displays simultaneously which are not in my eyeline. Bad enough at 20-30MPH but I'd also like to test at higher speeds to make sure I have a linear response.

I did find a more or less suiltable app, GPS Tracker, only issues is the time resolution is not great at a few seconds per record but should be useable, more frequently than I can check manually, also it only seems to do KPH but that's easy enough to convert. Like I say, this is only a one off task.

[stevieturbo]

you hardly need to do that.

just drive along in a gear at say 3000rpm....then use gps to view your speed. Job done. Make any adjustments.

Well the RPM is irrelevent as the speed signal comes from the gearbox output. What you suggest is pretty much what I have been doing but it's a bit dodgy trying to read 2 displays simultaneously which are not in my eyeline. Bad enough at 20-30MPH but I'd also like to test at higher speeds to make sure I have a linear response.

I did find a more or less suiltable app, GPS Tracker, only issues is the time resolution is not great at a few seconds per record but should be useable, more frequently than I can check manually, also it only seems to do KPH but that's easy enough to convert. Like I say, this is only a one off task.

of course rpm is relevant, it is what dictates what speed you go in any gear.

[GDCobra]

you hardly need to do that.

just drive along in a gear at say 3000rpm....then use gps to view your speed. Job done. Make any adjustments.

Well the RPM is irrelevent as the speed signal comes from the gearbox output. What you suggest is pretty much what I have been doing but it's a bit dodgy trying to read 2 displays simultaneously which are not in my eyeline. Bad enough at 20-30MPH but I'd also like to test at higher speeds to make sure I have a linear response.

I did find a more or less suiltable app, GPS Tracker, only issues is the time resolution is not great at a few seconds per record but should be useable, more frequently than I can check manually, also it only seems to do KPH but that's easy enough to convert. Like I say, this is only a one off task.

of course rpm is relevant, it is what dictates what speed you go in any gear.

What I mean is it's not relevant to what I'm trying to achieve, I'm interested in checking the roadspeed calculated in the ECU (by a gearbox output driven sensor) to true (GPS) speed,
For example if I'm goig 20MPH I could be in pretty much any of the 5 available gear and engine RPM would be different for each (probably between 1200-6000RPM).
This is partly why I want a correct reading for the roadspeed, so that I can determine what gear was being used at any time.
I guess if I'm honest accuracy isn't that important for that but if I can have it right why not get it so.

[stevieturbo]

which is why rpm is the primary number used for any gear ratio/speed calcs


You're really overthinking it

[GDCobra]

which is why rpm is the primary number used for any gear ratio/speed calcs


You're really overthinking it

I'm sorry Steve but I can assure you I'm not, I just don't think you understand what I'm doing.

All I'm aiming for is to check if the speed reading in the ECU is correct and if not work out how far out it is. The ECU monitors road speed directly from a sensor, RPM is not included in the calculation.
This could be done by simply monitoring and comparing the two readings but safer and easier to do this way..

Calculation of gear position is secondary and performed once speed and RPM readings are established. Once I have a drop of data logged from the ECU I can work out what gear I was in for any given record, but I already do that, this only depends on working out the ratio between speed/RPM. This value will be one of 5 different levels when the car is driving forward with the clutch fully engaged, I'm not concerned with reverse and most of that is done with clutch slop anyhow.

Obviously once I correct the road speed reading in the ECU, the speed/RPM ratios will change and I'll have to modify the calculation in my data processing program.

[stevieturbo]

I've tuned hundreds of ecu's., I know exactly what you're doing. It is very easy.

[GDCobra]

I've tuned hundreds of ecu's., I know exactly what you're doing. It is very easy.

Well I have to disagree, whatever you think I'm doing is not what I am doing if you believe RPM is of importance.
The only way I could use RPM to work out my speed is to know absolutely accurately what my gear ratios and effective tyre size is which I guess is calculatable but how would that be easier than simply measuring with a GPS speedo?
Even then the only gear ratio I know for certain is 4th as it's 1:1, the others I'm not certain about.
I don't understand which you think what I'm trying to do is complicated.

[GDCobra]

Just to close the loop on this I did some logging today with with an IOS app called "GPS Tracker Pro" by Marvin Wagner

This is a simple app and a bit limited but fine for the job I wanted. One issue is it only seems to work in those new fangled kilometer units with no setting to select good old fashioned miles but that easily sorted.

Unfortunately I can't post graphics easily here but having taken a selection of logs I can confirm that the speed calculated in my tweaked (x1.25) ECU is now very close to the GPS log, arguably the ECU is measuring 1MPH low. I'll crunch the numbers properly to get average deviation but I'm happy enough for the moment, at least proves my coding went the right way and multiplied rather than divided!

GPS logs (small sample)
Time KPH MPH
12:22:14 63.352915 39.3
12:22:15 63.352915 39.3
12:22:16 64.845504 40.3
12:22:17 64.470898 40.0
12:22:18 64.470898 40.0
12:22:19 63.430403 39.4
12:22:20 61.123988 38.0

14CUX reading
Time MPH
2024-11-02_12:22:16.051 41
2024-11-02_12:22:16.163 41
2024-11-02_12:22:16.370 39
2024-11-02_12:22:16.482 39
2024-11-02_12:22:16.594 39
2024-11-02_12:22:16.754 39
2024-11-02_12:22:16.865 39
2024-11-02_12:22:16.979 39
2024-11-02_12:22:17.138 39
2024-11-02_12:22:17.249 39
2024-11-02_12:22:17.410 39
2024-11-02_12:22:17.569 39
2024-11-02_12:22:17.681 39
2024-11-02_12:22:17.794 39
2024-11-02_12:22:17.952 39
2024-11-02_12:22:18.064 39
2024-11-02_12:22:18.176 39
2024-11-02_12:22:18.336 39
2024-11-02_12:22:18.496 37
2024-11-02_12:22:18.608 37
2024-11-02_12:22:18.767 37
2024-11-02_12:22:18.879 37
2024-11-02_12:22:18.991 37

[stevieturbo]

I don't understand which you think what I'm trying to do is complicated.

As already stated, it is not complicated, you are making it complicated.

It is very easy.

But you've got there in your own way.

[GDCobra]

I don't understand which you think what I'm trying to do is complicated.

As already stated, it is not complicated, you are making it complicated.

It is very easy.

But you've got there in your own way.

I agree it is not complicated but I fail to see how I've made it complicated or how I could have improved matters by taking RPM into account. I'll repeat, RPM has absolutely no bearing on what I'm doing.
I took the car for a drive and then compared two sets of values when I got home. Where is the complexity in that?