Speedometer tolerances - Chevy Cobalt SS Forum : Chevrolet Cobalt SS Forums
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post #1 of 14 (permalink) Old 05-26-2006, 12:23 PM Thread Starter
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Speedometer tolerances

So, I've noticed that my speedometer reads 3-4mph faster than I am actually going. Hooked up a digital obdii reader as well and it reads slightly lower than the analog gauge. My concern: If the car thinks I am going faster than I actually am, is my odometer counting faster that it should?
I understand that it's not going to be perfect, but there must be an acceptable tolerance for accuracy. Any idea what that is before I go to my dealer?
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post #2 of 14 (permalink) Old 05-26-2006, 01:37 PM
 
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yea it's 1-3 mph last time i checked. sorry the diffrence will add up after a while. just unhook the speed sensor from the tranny and take back a hundred miles once a year or something. lol
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post #3 of 14 (permalink) Old 05-28-2006, 05:12 PM
 
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Or just drop her off at GM lol. Damn, I thought SRT4 owners had it bad because the stock boost gauge always goes bad.
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post #4 of 14 (permalink) Old 05-29-2006, 01:02 AM
 
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You have a few mph variance for several reasons. PCM calibration based on OEM spec wheels/tires vs after market. The PCM tries to compensate for a margin of error within a 10% tire size range. 3 mph would fall into the acceptable range.
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post #5 of 14 (permalink) Old 05-29-2006, 02:38 AM
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Quote:
Originally Posted by West Palm SRT4
Or just drop her off at GM lol. Damn, I thought SRT4 owners had it bad because the stock boost gauge always goes bad.
lol, all cars are like this. manufacturers make cars so that the speedo will read slightly faster than you are actually going. saves them from lawsuits.


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post #6 of 14 (permalink) Old 05-30-2006, 10:06 PM
 
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lol, all cars are like this. manufacturers make cars so that the speedo will read slightly faster than you are actually going. saves them from lawsuits.
Haha lol true.
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post #7 of 14 (permalink) Old 06-03-2006, 03:12 PM
 
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Quote:
Originally Posted by iso
lol, all cars are like this. manufacturers make cars so that the speedo will read slightly faster than you are actually going. saves them from lawsuits.

I would have said cause thier lazy!
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post #8 of 14 (permalink) Old 06-04-2006, 12:39 AM
 
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That too. Engineers are lazy bitches.
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post #9 of 14 (permalink) Old 06-04-2006, 12:05 PM
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Originally Posted by wyoming_bass
I would have said cause thier lazy!
well, say you get pulled over and you think you're doing 65 because that's what the speedo says, but actually you were going 67 (or something), you could sue the manufacterer if everything on the car is factory stock. so manufacterers leave some leeway in the speedo to avoid situations like this no matter how rare it may be.


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post #10 of 14 (permalink) Old 06-04-2006, 12:06 PM
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oh, and trust me engineering aint easy.


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