speed/distance and ScanGuage II

[Digger]

When I first hooked up the ScanGuage II I noticed the speed was about 3% slower on the ScanGuage II than the speedometer read. As a result I adj. the ScanGuage II up by 3% to make them read the same. Now, the distance reads 3% more than the car odometer. Here is the question: Which one (of the car's) do you think is wrong the speed meter or the odometer?

[keithvibe]

I have noticed the the speed-o-meter is off on my car. I say this only because in PA in certain sections of the state they have a radar posting the traveled speed of your car. Each and everytime I pass by this my speed on my meter is faster than what is posted on the radar by 3-4mph.

[ColonelPanic]

My speedometer was wrong in the Vibe as well, but it was off by greater amounts the faster I drove. Due to that fact, I couldn't use the adjustment on the ScanGauge since it would be accurate according to the speedometer at the point where I did the adjustment, but once I left that speed it seemed to wander way off course. And the odometer was quite a bit out of whack then as well. So, I just left the adjustment at zero. I can't recall if the ScanGauge matched up with what my GPS was saying.I also found on the Accent that the speedometer is off as well, thanks to those radar signs keithvibe mentioned. It's about 3-4 MPH over at any speed, but the odometer is slow so at least I'm physically getting more than 100,000 miles out of my 100,000 mile warranty and the needle reading faster is keeping me out of trouble. I brought it up to the dealer, but apparently it falls within tolerance so they couldn't do anything about it. The GPS and ScanGauge with no calibration both show the same speed, so the the cluster is getting the right speed fed to it but doesn't read it correctly.If you have a GPS, bring it along with you and compare what your speedometer, GPS, and ScanGauge all say at the same time. If I had to guess what was wrong with yours, I'd say it is in the cluster. I guess most cars are likely to be inaccurate in some way or another, and everybody has a certain tolerance of just how much they can be inaccurate. There's no telling how far off the speedometers have been on stuff we've driven in the past, the only difference now is that we've got all these cool gadgets to show that the speedometer is wrong.

[RePo]

Scanguage II is accurate, don't change it. I have a TomTom GPS in the vibe, so I have three speed readings. The speedo in the vibe is accurate up to 40mph. After that the speedo reads high, where scanguage is perfectly accurate against the GPS (ultimate authority). To go 70 mph (true speed), the speedo will read 73. I've been told it's made that way to give speeders that false sense of speeding while reducing their actual excess. My other cars are dead-on accurate across the board ('97 chevy and '98 chevy).

[Digger]

I set thespeed setting on the ScanGuage II back to 0.

[ColonelPanic]

Quote, originally posted by RePo »I've been told it's made that way to give speeders that false sense of speeding while reducing their actual excess.It's amazing how well their little psychological trick works. Here I am, armed with the knowledge that I have confirmed my speedometer is inaccurate and know the exact amount... Yet every time I look at the speedometer, I'm still too stupid to realize what I see isn't how fast I'm actually going. "better slow down, dude" I'll say.. I can even have the GPS nearby and have looked at the speed I was traveling within the last minute or so, I still get fooled.

[Digger]

It seems the speed-o-meter is not concistant. it some times reads the same as the ScanGuage II. I think the dif. si the degree of error on the speed-o-meter

[Digger]

gas used was almost right on as far as what it said I used and the gas I pumped in out of the box. I put in 7.9 and it read 7.6 gal. used. that was the calibration tank. I will post the result next fill up as to how much it is on/off. MPG read 26.7 which was close to what I calc. on my own