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Discussion Starter #1
Has anyone with a scan tool (I'm using the predator) noticed the speedo is not the same as what the tool is showing??

My car DIC is 3mph higher than the tool. Anyone know which one to believe?
 

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Yes, it has a car seat
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My understanding is that the best way to check this is with a GPS unit and a straight highway run.
Dan
 

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Haven't tried a scan tool, but my analog is about 1mph higher than DIC, which in turn was about 1-2mph higher than GPS.
 

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Discussion Starter #4
How accurate can the GPS be? I thought the gov. scramble the signal so it wasn't accurate enough to launch a missile at the white house.
 

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Knight Errant
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mlc said:
How accurate can the GPS be? I thought the gov. scramble the signal so it wasn't accurate enough to launch a missile at the white house.
10 feet +/-
 

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My digital speedo is 1 mph lower than the analog needle reading in my cluster. So now, when the officer pulls me over, I have an excuse to tell him that I was confused....Was I going 130 mph? or 129??????

I guess I'll have time to ponder the answer while waiting for my lawyer to bail me out.

LOLOLOL
 

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I went by a Police radar control box today. Its a big read out machine to do speed control. It read 2mph faster than my digital read out. I can increase my edge limit maybe not!!!???? Who's correct

Cos :secret: :eek2:
 

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Oh my f*ck!
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mlc said:
How accurate can the GPS be? I thought the gov. scramble the signal so it wasn't accurate enough to launch a missile at the white house.
They do not "scramble" the signal. There are different codes that are used based on whether you are a commercial or a military/govt user. A receiver that can use the mil/govt code (P(Y) code) has a crypto key such that it knows how to jump to the correct code. A commercial receiver can usually only receive code L1, but there are some that can use L1 or L2. Then you have WAAS (Wide Area Augmentation System), which is an entirely different story and only works in certain parts of the US (but it works very well).
 

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May I quote you on that?
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My speedo reads 2-3 mph higher than gps or measured mile at 60 mph. Also reads higher than VSS, however I can't read VSS to a tenth with my software. Gps and measured mile correlate exactly.
 

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DOG
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This is standard among most cars. For safety reasons they want you to think you are going faster then you are. The exact amount is about 2.8 mph faster then you are actually going. This looks to be handled on the DIC itself in the GTO. As a result you can't EVER go 1mph.
 

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May I quote you on that?
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tiggerfan said:
This is standard among most cars. For safety reasons they want you to think you are going faster then you are. The exact amount is about 2.8 mph faster then you are actually going. This looks to be handled on the DIC itself in the GTO. As a result you can't EVER go 1mph.
AHAA! That must be why EfiLive says 2 mph while I'm standing still!
 

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Acording to my GPS my speedo is 1 mph fast.
Also checked it ina well known School zone with radar bill board and that also showed 1 mph faster.
 

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mlc said:
Has anyone with a scan tool (I'm using the predator) noticed the speedo is not the same as what the tool is showing??

My car DIC is 3mph higher than the tool. Anyone know which one to believe?
Mine is 3mph exactly off from what the PCM reports too.
 

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Austrlian manufacturers build in around 5% overestimation on speedo accuracy (ie 3mph at 60mph). This allows for tyre rolling diameter change as they wear, but also to help protect their customers from the ever present speed cameras. Most Australian states have a 1-2mph allowance before you will be booked, so 5% usually means you can sneak slightly over the limit without actually breaking the law.
 

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Discussion Starter #17
With the Predator you can specify the tire size and another value that isn't coming to mind right now. Do you think these can be changed so the DIC is more accurate?
 
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