Speedometer Problem

[Drew707]

Hey guys/girls. So i was driving on the freeway the other day with my GPS with me. my gps shows my accurate speed. my Speedometer Reads 65mph, but the GPS reads 77mph. I was wondering why i was in the fast lane passing everyone when my speedo only read around 60. Whats the problem here? Im on stock wheels and tires so why would it be so inaccurate?

 

[Drew707]

sooooooo anyhelp?

 

[russiansohcf23]

I also have this problem too, when my speedo says 65, the gps says 60. Not all cars are perfect.

 

[finch13]

My post didn't show up?

Double check the tire sidewall, they should be 195/65/15 in size. Also make sure they're inflated correctly (~35psi or so).

If it's not the tires I would suspect a corroded connection between the speed sensor and the ECU/gauge or a faulty gauge.

What is your engine RPM when the speedo reads 70? It should read, correct me if I'm wrong guys, 3000 at 70 mph for the auto and 3000 at 80 mph for the manual.

 

[russiansohcf23]

Im at 3000 RPM's at 80mph and im auto. But I do agree with finch13 about the tire pressure, might wanna check on that.

 

[finch13]

Maybe I don't know my car as well as I think... us manual should be a few hundred lower than you at cruising speed since we have 5th gear.

 

[Drew707]

My post didn't show up?

Double check the tire sidewall, they should be 195/65/15 in size. Also make sure they're inflated correctly (~35psi or so).

If it's not the tires I would suspect a corroded connection between the speed sensor and the ECU/gauge or a faulty gauge.

What is your engine RPM when the speedo reads 70? It should read, correct me if I'm wrong guys, 3000 at 70 mph for the auto and 3000 at 80 mph for the manual.

yea my tires are all 195/65/15 and inflated to 40psi. 44max. my rpm is at 3k but my speedo says 60ish. using a automatic. when im at 70-75mph on my speedo my Tach says 3500 about 4k.

 

[finch13]

Interesting...

It's late and I may be overthinking this, but I wonder if the tranny is slipping and the computer isn't locking up the torque converter like it should. I would verify the rpms vs. speed thing with the GPS though.

 

[Drew707]

Interesting...

It's late and I may be overthinking this, but I wonder if the tranny is slipping and the computer isn't locking up the torque converter like it should. I would verify the rpms vs. speed thing with the GPS though.

i guess i forgot to mention that my tranny slips pretty bad from 1-2, 2-3. ill verify the rpms vs speed with my gps 2morow wen i drive again

 

[RedAccord02]

damn 3k for me is about 75 -80 somethings def wrong