Jump to content

Filter for speed input/output


Recommended Posts

Ok, so I am having issues with the speed signal on my EF Falcon, but only when the signal is run through the Link. Direct to dash it works fine, so it seems the dash doesn't like the Link's output signal.

I have it wired through the Link (DI 1, Aux 4) so I can calibrate the factory speedo for changed diff ratios. (And gauge sweep is cool AF)

The signal is being provided by the factory VSS on the transmission. (625 pulses per 100m)

At lower speeds it is fine, but above around 80km/h the needle starts to wander a bit and gets worse as speed increases. At 100km/h for example it will jump around +/- 6 or 7km/h.

The runtime value doesn't help much as the numbers change so fast it's hard to tell what it is reading.

I have tried changing the active edge between high/low side but no difference.

A filter on the signal, or an option to average the output/input may be what I need, as using the average speed on the factory trip meter seems to give a near perfect reading. 




Link to comment
Share on other sites


It may worth recording a log so you can look at the digital input speed and frequency at your own pace. The digital input channels are designed to accept a maximum of 500 Hz, by my rough calculation you shouldn't be hitting this limitation until about 290 km/h.

Is the sensor a hall or reluctor type sensor?


Link to comment
Share on other sites

I should have thought of that. Thanks.

I'll add the input and output to ecu logging. That should give me a better idea of what's going on. 

It's a hall sensor, and now I think about it I should check the power side of it as the power comes from the dash.


Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...