Speed sensor question

[ducman82]

ill will try the update.

would messing with the smoothing/vssdot sampling might help?

i only have a mac laptop, so I'm not sure how to do a sound card scope

[jsmcortina]

vssdot smoothing impacts vssdot. This looks to have a mechanical problem or an input signal problem - they need fixing before trying to bandaid it with smoothing.

James

[ducman82]

Hmmm ok, i will check the sender wiring, and wiring crimps etc... stock speedo is working like a champ, no fluctuations....

i just updated the firmware. that new MAC OS updater works like a champ FYI.

[ducman82]

after the update, it works worse...

maybe i will have to add a secondary wheel speed sensor somehow.....

[ducman82]

all the connections are good.

anyone know of a good scope i can get? nothing stupid expensive.....

[grom_e30]

http://forums.pelicanparts.com/porsche- ... sting.html

not sure if this is the same as your one but worth a read.

[ducman82]

ya, thats the sensor. ill be it a test. but I'm pretty sure it working..

maybe i should try one of this?
http://www.jbperf.com/dual_VR/v2_1.html

and not that ZEAL board i made.... maybe i messed it up some how...

[grom_e30]

that says it is a reed style switch not a vr sensor (just like my bmw) if thats the case you can probably clean the signal up with a hex inverting schmitt trigger thats what my bmw vdo clocks do with the signal before its passed on to the stock ecu.

[ducman82]

Hmmmmmm.......... would that chip replace the Zeal board? how did you wire yours up?

[grom_e30]

i didnt have to use one on my ms3 setup as its already one built in to my speedometer, but i did use one on a speedometer corrector i built for my bike(digital speedo) as the was a bit jumpy when not at a steady speed and it cleared that right up. its would be a simple circuit to build a 74hc14 (SCHMITT TRIGGER) a couple of capacitors and possibly a pull up resistor if needed.

[ducman82]

after a few months, all seems to work fine. now when at speed, its about 3-5 mph off. lag factor smoothing does not seem to change that much.. any other way to figure that small difference out?

[Laminar]

Once up to speed I had my wife play with the wheel diameter until the VSS readout matched my phone's GPS speed. Tires deform depending on load and speed so the actual diameter will vary from the "nominal" value for tire diameter that was calculated from the tire's supposed size.

[ducman82]

good point! ill give that a shot.