Speedometer 11mph off

[fulanititoo8198]

I have 245/45/17's (falken azenis) With a 25 1/4" Diameter. Stock is 24.88 from what I've found. About a 3% difference in diameter so wouldn't that lead to a 3% speed calculation error? My speedometer should read slower not faster I don't get it.

IE: If I am going 30mph my speedometer will show 41mph and dsmlink shows about 30mph as well. So my question is what causes my speedometer to read 11mph off when dsmlink is logging accurate mph? Don't they work together? I've never removed the needle on the speedo.

Thanks,
Cristian

 

[Defiant]

I wonder if you're running an AWD speed sensor, but I'm not going to put the thinking into figuring out if that would make it faster or slower. AWDs are geared lower than FWD, and... ow.

I knew I shouldn't have tried that.

 

[TurkF26]

I may be wrong here but in DSMLink you can put what size tires you have, rims, etc... and if im not mistaken, it will correct your gauge cluster or does it only affect what DSMLink is logging???

 

[fulanititoo8198]

I wonder if you're running an AWD speed sensor, but I'm not going to put the thinking into figuring out if that would make it faster or slower. AWDs are geared lower than FWD, and... ow.

I knew I shouldn't have tried that.

Hmm I've never changed the sensor so it should be fwd. I do have an awd ecu though.

 

[fulanititoo8198]

I may be wrong here but in DSMLink you can put what size tires you have, rims, etc... and if im not mistaken, it will correct your gauge cluster or does it only affect what DSMLink is logging???

It does have that setting but it's for other purposes. Even then I have it set correctly to my wheel setup.

I was messing with the car yesterday and I noticed that the car is reading about 100 rpm lower then dsmlink as well.

 

[TurkF26]

Ya with my DSMlink i have also noticed that the RPM's are a little off too compared to the stock cluster. I do not though have any problems with the MPH being off.

 

[fulanititoo8198]

Update I fixed my problem, took of the needle went a certain speed on a logger and made the needle match the log. Works great now.

 

[Raph]

just so all you guys know.. speedos in cars generally are accurate to 30mp.. any faster and there all wrong..its normal because of the dynamic changes in your tires circumfrence at speed ..

and all the guages arent precise measuring instruments .. its normal for the tach to be a few rpms off.. ive seen as much as 800 rpm difference before

 

[Boostmonkey]

I have the same thing happening in my car, my speedo is ~10mph faster than it should be.
Does this mean the odometer rolls over faster as well? i had gotten used to the speed, but i never paced it to see if the odometer was wrong. i have the same size wheels/ tires as the OP also... Strange.

 

[redyute1]

got me a 92 1.8 and the speedometer reads 5 mph faster than the car is actually going looks like this is a common thing with the 1g's