I don't care what motortrend says, I hooked up a honda pgm tester to my civic and my speedo was fast only by 2 mph then actual. So I still don't see how you got 127 at 140.

 

the margin of error on most if not all speedo goes up as the speed increases.

i know in my car at 60 i'm doing about 59 but around 120 indicated is more like 110-112 ish.

also a cheaper way to find out the speedo accuracy (well cheaper than getting clocked by a police car :exnbp: ) is to borrow a GPS. most decent ones will give you the speed read out and it's 99% accurate.

 

I am going to try this. Just for sure curiosity that is.:thumbup:

 

or you could be a hondatech and have a honda pgm scanner, im going to do it today, i'll hit 138 or whatever then look at the datalist for my speed sensor and see what it's actually doing.

 

okay but don't get killed or busted for speeding

but keep in mind that would be one data point. also do you have the stock tires/wheels? I know my speedo became much more accurate when I changed tires to a slightly larger size

 

actually I have a set of 18'' on now, They will come off in a week so I will try then

 

18s ? Your a :grinpimp:

 

I tried the gps idea and figured that when my speedo said 55 MPH I was actually going 53 MPH by the gps.