Has anyone else been having problems with there speedometer being inaccurate? I have had 2 people follow me on the highway. When my speedometer says I am going 75 I am really going 70. And when it says I am going 85 I am really only going around 79. I have taken it to the dealership and they pretty much said that there was nothing that they could do. Does anyone have any suggestions?...besides kicking the service manager in the nuts

 

BTW, I have also checked it with one of the police radar guns that they put up on the side of the road to show you your speed. Gauge said 45 and I was only going 43.

 

Are you on stock wheels and tires?

 

That's a new one, never heard anyone complain of it before
It really cant be out that far, unless somethings changed like tire size.
What do you run for tire pressure?
All the dealer can do is reflash your PCM (where the speedo calibration exists) in case it's corrupted somehow. (assuming you are using the factory tune of course and not HPT or something like that) or maybe replace the speed sensor in the transaxle but if the speedo's working the VSS is as well. Weird
Wop

Edit: Come to think of it- I would have someone maybe use a scan tool to compare the PCM parameter for Vehicle Speed to the indicated speed on the gage in the cluster. Maybe there's something wrong with the cluster

 

Well, it'll save you from getting a ticket, are your tires stock or at least the stock size? Clutch slipping?

 

Yes, everything is stock. I will have to call tomorrow and find out what they did. But they said something about using a scan tool. I will have to call and see exactly what might be the problem. But it is definitely inaccurate...

 

Ohh, tire pressure is the recommended 32 psi. But like I said everything is stock. There would have to be something majorly off to account for the 10% discrepency (sp?).

 

i like my front tires at 36 and my back at 34

 

Don't need to worry about that, that is what the radar detector is for.

If I knew that my speedometer was off by 5 miles an hour, I probably wouldn't have bought it.

 

32 psi on 18's... where are these specs at? last time I checked when I had my 245/40/18 on my grand prix my psi needed to be at about 40

 

specs are on your door...mine are at 26-27 psi right now (oops) but im going back up to whatever it says on the doorpanel tomorrow.

 

youve been showing a 3-5%79 when 85...or else it would be about 76 when 85

 

You have anybody that can GPS confirm your speedo being off??

 

I used my LS1 scanner and the speedo and tach are dead on.

 

Mine reads to fast as well, I was reading 130 and friends were at 122 or so.

It's just a **** off cause km's are going on quicker then they should, which is the reason my next tires will be a little bigger 225/35.

 

I havent bought a car mag in forever,but all of the bike mags that are worth a damn give you the speedo error at 30 and 60 mph.Sometimes at 60 its around 3-4 mph and just keeps going up the faster you go.Now ,as to our speedos, I have no clue how acurate they really are.Ask a cop to help test it.

 

car companies dont make speedos to be accurate above 55mph for the most part, they could really care less
think youre really doing 145?? doubt it