Syvecs Forums

Hi,

For some reason I'm now getting very spikey readings (logged) for Vehicle Speed - See attached log... and this is causing some issues with my DCCD setup.

I do not have the filtering on, and the upper and lower voltage thresholds are 1.25v, 3.75v.

Would turning on the filtering cure this (its simply on/off for vehicle speed yes?)? I havent looked real time to see what the sensor is outputting, but it seems stable at times :S Those times match when vbat is above 13.5v



Also, The speeds seem sonsense, not mph or kmh from the speeds I know I will have been doing. Radar is set to 1.6 for diameter. Anyone have a better value off the top of their head (pavlo?)?

upload the map, although those readings look pretty wild.

What age car ?

Does it have a sender in the box, or does the speedo run via cable and the speedo head send a signal to the ecu ?

map uploaded, its a 98 sti4, with an RB320 6speed dccd box.

No idea on actual wiring. Its has a speedo pickup in the box, and clocks read in kmh

I think first off it would be worth logging AN05 raw values at a highish rate to see what the voltages/signal is actually like, then you could play with the settings to try and make it more stable as you know what you're working with.

But you could try turning the filter on on radar too.

As for actual displayed speed, you'd need to adjust the relevant tyre circumference until displayed speed is correct for the tyre in use. Your numbers there seem very low.

ta, added AN05v to logging config, and will capture some data on sat.
I've turned the filtering on for now anyway, but cannot test on the road.

Sitting at idle, on the trailer, without wheels turning - 4.95v with small fluctuations +/-0.3v

TrackScotland wrote:ta, added AN05v to logging config, and will capture some data on sat.
I've turned the filtering on for now anyway, but cannot test on the road.

Sitting at idle, on the trailer, without wheels turning - 4.95v with small fluctuations +/-0.3v

log at a decent rate, say 100Hz

yup, will do.

Just had another look, as I saw from another log that the speed was spiky even at idle. With the car idling and filter off - the gauge for vspeed in SCAL was showing 0-40. Changed to filter on (radar) - flashed and started up again. Let it idle for a few mins but speed showed as a stable 0.

Hopefully thats taken care of that, but will look into trying to stabilise it anyway.

ta

At the track and tested. Speed seems stable with the filtering, but logging on thermister / an05 shows massive fluctuations.

See pic. At constant speed or idle the voltage is flipping from 4.98 to 0.1 for example.

obviously the voltage at speed will be switching high and low, that's just how the sensor works.

When stationary though it definitely should not be.