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M1tch

Can I adjust speedo?

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Hi all,

I will be plugging my Link Xtreme into the car over the weekend, I was just wondering if there was a setting where I am able to adjust the speedo ratio so that I can run different wheels/tyres, the car doesn't have the most common tyres so it means that the alternatives aren't the best - if I am able to adjust the speedo ratio within the Link I would then be able to run any wheel and tyre combo I want.

Thanks in advance!

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17 minutes ago, Adamw said:

Yes, provided your speedo is electronic and you connect it to the ecu, then you can adjust it.  You need to connect the speedo to aux 1-8, assign the aux to "speedo out". You will then get these settings:

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That's great, thank you! I haven't yet gone into the PC link software, basically just looking to plug it in so I can unlock it etc, the ECU is being wired into a mk3 MR2, I believe its running partly as a piggyback to retain some of the stock controls but the speedo is driven electronically so it seems I should be able to adjust it. Is it a case of simply putting in a correction figure?

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4 minutes ago, Adamw said:

Yeah the offset will be used say if your speedo is out 10kmh at all speeds, the multiplier will be used if say the error is linear - for instance the error at 100khm is double the error at 50kmh

Perfect, will go into the PC link software later and have a look, with my current wheels and tyres the speedo is fine, however once I start running another 200% more power over stock I might need to look at wider tyres!

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14 hours ago, Simon said:

If you are changing tire size you would be better to rescale the digital input calibration so then the ECU is reading the correct speed and just passing it through.

I will need to see if that is even possible with the car - its an MR2 ZZW30.

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Its a function in the ECU. On the Digital input there is a calibration figure. Adjusting this allows for different wheel sizes.

 

A Digital Input may be connected to an electronic wheel speed or vehicle speed sensor (typically located near the output of the gearbox, or as an output from the vehicle dash board) to enable speed to be calculated.  These Digital Inputs can then be used to configure the Driven and Non-Driven Speed Sources.

 

  The Calibration number allows the ECU to calculate speed in km/h.

 

  Note:  In some cases erratic speed signals can occur due to unusual speed signal shapes.  Changing from Rising Edge to Falling Edge or vice versa may help with this problem.  This problem usually presents as random spikes of increased speed.

 

  Set-up Procedure:   The Calibration number is the number of pulses received over a 100 m distance.

 

  Method 1:  Drive the vehicle at a known speed and adjust the calibration number until the Vehicle Speed Runtime Value displays correct.

 

  Method 2:  Wheel Speed Sensors Only.  Calibration Number = (Number of Sensor Teeth / Wheel Diameter) * 31.83.  Note that wheel diameter is in meters (m).

 

  Typical values for speed calibration numbers range from about 170 to 280. The maximum frequency the digital input can accept is 500 Hz.

 

 

  Note:  Wheel Speeds can be checked in the Runtime Values Digital Inputs tab

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