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Topic: VmsPC speedometer question (Read 534 times) previous topic - next topic

VmsPC speedometer question

My dash speedometer shows a little bit of needle wobble. No problem.

But VmsPC shows the correct speed most of the time. Slight +|- 1 mph fluctuations. And then an occasional + 5 mph spike. Or a series of spikes. When I glance at the display my first thought is I'm going too fast.

Is there some damping parameter I can change so it acts more like the dashboard speedo?
Tom Lang K6PG (originally  KC6UEC)
and Diane Lang
2003 38 U295 build 6209
2016 Jeep Grand Cherokee Summit Ecodiesel
still have tow-ready 2006 Acura MDX 
Temple City, California
Motorcade 16681 California Chapter President
SKP 16663 member of SKP Park of the Sierra, Coarsegold California
FMCA F071251
Retired electrical and electronic engineer

Re: VmsPC speedometer question

Reply #1 –
Quote from: Tom Lang –
My dash speedometer shows a little bit of needle wobble. No problem.

But VmsPC shows the correct speed most of the time. Slight +|- 1 mph fluctuations. And then an occasional + 5 mph spike. Or a series of spikes. When I glance at the display my first thought is I'm going too fast.

Is there some damping parameter I can change so it acts more like the dashboard speedo?

Just shooting into the dark here. Could it be the speed sensor itself? A bit dirty or bad connection?  On our coach, The VmsPC and the OEM speedo is dead accurate to the GPS and I haven't seen any spikes at all.
Jerry & Nona and Kimeru the cat that thinks she's a dog
1998 36' WTFE U320  #5314 Motorcade #17711
USAF 1975-1995
2019 Subaru Crosstrek 'toad'
2003 Subaru Legacy touring car
jerry Fincher | Flickr

Re: VmsPC speedometer question

Reply #2 –
Sounds like a speed sensor/ dirty connector. Like Bigdog mine is dead on both speedo and VMSPEC.
Bruce, Linda, and Macy
Zoey RIP 1/20/19
1999 U295 40' build #5400
2017 silver Jeep Wrangler, 1260 watts of solar on top
Moving around the country

Re: VmsPC speedometer question

Reply #3 –
VMSpc reports speed based on what the engine computer reports.  It does not use any mechanical speedometer connections.  Speed is based on data originally provided to the engine computer, tire and wheel size, drive ratio, gear you are in and rpm.  Tire revolutions convert to distance over time gets you MPH.  The same calculations get you distance.  The engine computer reports this over the data bus.  VMSpc grabs the data as it comes over the bus and reports it.  Silverleaf tells me there is only a small amount of smoothing or averaging going on. They tell me that the next release (due out almost a year ago) will have more aggressive ability to discard data that is significantly out of range and do some additional stability management.  How is that for promotional speak?

So for now it is up to you to ignore the outliers.  Don't worry too much about it.  For some engines the 3.x versions work a bit better.  For most the 4.0.8 version will be fine until version 5 comes out.

My dash speedo reads just under VMSpc.  Odometer reads about 1% low compared the the computer.  I am going with the engine computer.

You can put in corrections (relative and absolute) for these reading under engine corrections.  The correction is the hard part to figure.
Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN

Re: VmsPC speedometer question

Reply #4 –
Gee Roger, You should go on TV and help sell flex tape.  :))
Jerry & Nona and Kimeru the cat that thinks she's a dog
1998 36' WTFE U320  #5314 Motorcade #17711
USAF 1975-1995
2019 Subaru Crosstrek 'toad'
2003 Subaru Legacy touring car
jerry Fincher | Flickr

Re: VmsPC speedometer question

Reply #5 –
Mine does the exact same thing while driving.. Now sitting is another story... it does nothing :))  ^.^d 

Re: VmsPC speedometer question

Reply #6 –
I was hoping the smoothing parameter was user defined. Oh well.

Thanks
Tom Lang K6PG (originally  KC6UEC)
and Diane Lang
2003 38 U295 build 6209
2016 Jeep Grand Cherokee Summit Ecodiesel
still have tow-ready 2006 Acura MDX 
Temple City, California
Motorcade 16681 California Chapter President
SKP 16663 member of SKP Park of the Sierra, Coarsegold California
FMCA F071251
Retired electrical and electronic engineer

Re: VmsPC speedometer question

Reply #7 –
Under the Advanced Menus/Engine Corrections make sure you check the Request Fuelmeter and Odometer boxes.  I guess this prompt the computer to send this data more often.
Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN
 

Re: VmsPC speedometer question

Reply #8 –
Quote from: Roger & Susan in Home2 –
Under the Advanced Menus/Engine Corrections make sure you check the Request Fuelmeter and Odometer boxes.  I guess this prompt the computer to send this data more often.

Thanks. It's worth a try. More frequent samples would likely help. Less delta v between samples.
Tom Lang K6PG (originally  KC6UEC)
and Diane Lang
2003 38 U295 build 6209
2016 Jeep Grand Cherokee Summit Ecodiesel
still have tow-ready 2006 Acura MDX 
Temple City, California
Motorcade 16681 California Chapter President
SKP 16663 member of SKP Park of the Sierra, Coarsegold California
FMCA F071251
Retired electrical and electronic engineer