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Old Thu, Aug-08-2013, 01:06:07 AM   #21
terraphantm
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Default Re: DIY: Eliminate Speedometer Error

Quote:
Originally Posted by Bill33 View Post
Question: Does the error carry over to the ODOMETER? That is, does the indicated odometer reading reflect the 9% error? So my 95,000 miles are actually only 86,450?

Seems like some weird voodoo to have the speedo reading incorrectly at 9% and the MPG calculator running off of ?what?, and a trip meter showing...?what?, and an odometer reading...?what?
Odometer is separate and accurate. BMW deliberately introduced an error for the speed. The cluster knows exactly how fast it's going (unless you mess with the tire settings). Before the speed signal gets to the "needle", it is "multiplied" by 1.088. The odometer, mpg calculations, DME, etc. all occur before that multiplication step.
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Old Thu, Aug-08-2013, 01:57:01 AM   #22
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Default Re: DIY: Eliminate Speedometer Error

I get 5mph lower on a separate OBDII reader than what the cluster shows.
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Old Thu, Aug-08-2013, 02:01:52 AM   #23
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Default Re: DIY: Eliminate Speedometer Error

kudos! thanks for posting this DIY
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Old Thu, Aug-08-2013, 05:45:08 PM   #24
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Default Re: DIY: Eliminate Speedometer Error

Thanks, terraphantm!

Do you know by chance if the cluster is flash-count limited like the DME?
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Old Thu, Aug-08-2013, 06:45:19 PM   #25
terraphantm
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Default Re: DIY: Eliminate Speedometer Error

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Originally Posted by tallpgr View Post
Thanks, terraphantm!

Do you know by chance if the cluster is flash-count limited like the DME?
If it is, then I'm in trouble -- but I don't think it is. Any time you get a feature changed at the dealer, it flashes the cluster (even if you don't change cluster settings). If there were a limit, it'd be in the manual since the personalized settings are an advertised feature.
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Old Sat, Aug-10-2013, 10:27:25 PM   #26
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Default Re: DIY: Eliminate Speedometer Error

Feedback: Just did this today on my 2005. Speedometer speeds now almost spot on with GPS speed (maybe a percent low).

With relatively new Michelin PSS in OEM 19" sizing (225/255).

Thanks again!
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Old Sun, Aug-11-2013, 01:43:11 AM   #27
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Default Re: DIY: Eliminate Speedometer Error

This has to be one of the most practical DIYs I've ever seen. I hate the error, hate it when finely tuned machines have non-sensical errors put in by default...

What USB to OBDII cable are you using?

Last edited by pachieh; Sun, Aug-11-2013 at 02:06:35 AM.
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Old Sun, Aug-11-2013, 02:39:25 AM   #28
terraphantm
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Default Re: DIY: Eliminate Speedometer Error

I was thinking, I should probably list some 1% - 3% error configurations just to account for different tire sizes:

Code:
1%: 03 00 64 C8 00 65 CB
2%: 03 00 32 C8 00 33 CB
3%: 03 00 64 C8 00 66 C9
Also I want to mention that I still have no idea what that "C8" value does -- it might be a shift of the percent, a maximum limit to the error allowed, or something else entirely. If you want to try one with that value set to 0 as well, here's such a code. I have not tested this:

Code:
03 00 01 00 00 01 02
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Old Sun, Aug-11-2013, 03:19:22 AM   #29
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Default Re: DIY: Eliminate Speedometer Error

Quote:
Originally Posted by pachieh View Post
What USB to OBDII cable are you using?
BMW Scanner (1.4) has it's own OBDII interface, I don't think it is a standard OBDII->serial interface. I know the software won't recognize any of the standard KKL 409.1 (VAG-COM) cables I have. You also have to run BMW Scanner under one of the "supported" OS versions like Win XP. Win 7 driver interfaces appear to not be compatible.

Quote:
Originally Posted by terraphantm View Post
I was thinking, I should probably list some 1% - 3% error configurations just to account for different tire sizes:

Code:
1%: 03 00 64 C8 00 65 CB
2%: 03 00 32 C8 00 33 CB
3%: 03 00 64 C8 00 66 C9
These are to increase the indicated speed by 1-3% right? As opposed to lowering it for undersized tire circumferences...
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Old Sun, Aug-11-2013, 03:21:03 AM   #30
terraphantm
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Default Re: DIY: Eliminate Speedometer Error

Well I meant variability between tire manufacturers for a given tire size. For actual tire size differences, I would edit the impulses per KM setting
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Discussing DIY: Eliminate Speedometer Error in the Coding and Tuning Forum - Discuss all avenues of coding and tuning here! at BMW M3 Forum.com (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X)