Speed display on Virtual Dash not correct?

[GHZ28]

I have a 2004 Adventra which has been tuned with HPTuner and is now much improved, and with far better fuel economy, not chasing max HP in this car more addressing the relatively high fuel consumption when standard.

What I have noticed is that the vehicle speed as displayed on the virtual dashboard, this vehicle only-correct speed displayed on two other vehicles, is 4% higher than actual. For example, 105 km/h on digital dash display = 109 km/h on the HPT virtual dash. The digital display in the car is correct, within 1 km/h as verified by a certified radar device used in the same vehicle. (I sell these devices so one is permanently in my car)

I don't understand how the speed displayed onboard can be different to an external interpretation of the same data. We also can connect a plug to the OBD-II connector which reads the speed data from the ALDL port to provide a +/- 2km/h window for the radar to determine a patrol speed, this function also works correctly.

Any ideas from any of the forum members?

Garry

[Magic_Chicken]

I noticed mine doesn't seem to be 100% either, the virtual dash or my speedo. I compared it to my GPS (Garmin StreetPilot III), the virtual dash is slow and my speedo is fast. I wasn't that worried about it, but since someone else mentioned it...

[arthansen]

OK, I will chime in. My GPS and HP Tuners are identical (after recalibrating, I changed rear ends) but my speedo is 1 mph low at 70 mph. :-/

[Chris@HPTuners]

I have a 2004 Adventra which has been tuned with HPTuner and is now much improved, and with far better fuel economy, not chasing max HP in this car more addressing the relatively high fuel consumption when standard.

What I have noticed is that the vehicle speed as displayed on the virtual dashboard, this vehicle only-correct speed displayed on two other vehicles, is 4% higher than actual. For example, 105 km/h on digital dash display = 109 km/h on the HPT virtual dash. The digital display in the car is correct, within 1 km/h as verified by a certified radar device used in the same vehicle. (I sell these devices so one is permanently in my car)

I don't understand how the speed displayed onboard can be different to an external interpretation of the same data. We also can connect a plug to the OBD-II connector which reads the speed data from the ALDL port to provide a +/- 2km/h window for the radar to determine a patrol speed, this function also works correctly.

Any ideas from any of the forum members?

Garry

The instrument cluster has it's own calibration capabilities. Sounds like someone has tweaked it since the PID we log for the scanner is the SAE PID for Vehicle Speed. The PCM reads the VSS sensor and outputs a signal to instrument cluster that it then uses to drive the gauges.

Not exactly sure what you mean when you plug something else into the OBD2 port and it works fine?

Chris...

[GHZ28]

Hi Chris,

as far as I know, the dash has not been recalibrated, not by me anyway, and the speed displayed agrees exactly with the radar and a GPS.

We have a device which reads the vehicle speed from the OBD-II connector that is an option for the radar, to check the radar speed agrees with the vehicles onboard speedo, and it agrees with the radar.

So far, the only different speed I am seeing is in HP Tuner, not that it is a problem, just something I noticed.

Regards,

Garry

[Chris@HPTuners]

strange, assuming we are reading the same data i don't see how it can be out... :-/

[GHZ28]

strange, assuming we are reading the same data i don't see how it can be out... :-/

That is what has me intrigued too Chris.

As I said, it is not a problem, and probably only noticed by me because of the multitude of certified speed displays in the vehicle......lol There is always at least one radar, often two, a GPS and the radar logger feed.

Now, if I could get both the logger and VCM adaptor plugged in simultaneously, maybe then I could get to the bottom of it. But I guess OBD-II double adaptors are neither available nor practical.

Cheers,

Garry