Q&A Forum
Hi there,
Im running a braked dyno and which i bought second hand with yourdyno. Im trying to get steady figures from it which i cant seem to dail in. There is a rpm sensor (b5vaig) which seem to be working and feed data to the the yourdyno. Im experiencing that the rpm's are not stable. For instance if we use the tacho function in the rpm setup and use 4000 rpm, lock ratio, the rpm is only valid for this rpm. If we go under or over theshown rpm's are off.
We have moved the pulses per seconds value to a lower number and that seems to effect the error somewhat. Its currently at 46(have read that yourdyno needs at least 200)
We have tried to pick up the rpm from odb2 with the scantool plugin with works but on the run screen it does not see those rpm's a a controlling element. it still uses the roller rpm with ratio for braking and such. we could not find a way to tell the yourdyno software to take the rpm from the scantool feed. Is there a way to do this?
I hope someone can help us or point us in the right direction.
Thanks in advance!
Kind regards,
Vincent
Hi,
You have misunderstood the concept of pulses per revolution. It is not pulses per second. Pulses per revolution is how many RPM pulses YourDyno sees when the brake or roller rotates 1 rotation. So it is not a trial and error thing.
The b5vaig is a rotary encoder. I found a datasheet, but I am unsure if it is the right one, you need to give the full part number and manufacturer. If the one I found is correct, then this encoder can be had with from 1000 ppr (pulses per revolution) to 10000 ppr, which are all extremely high. You can still try (enter the correct ppr). But if you find a problem, then you know what you need to do! (Replace the encoder with one with say 20-200 ppr or so).
OBD2 is enabled only for engine RPM by design, because it is too slow for brake RPM (due to calculation of power from acceleration).
Hi there!
Thank you very much for your reply! Im trying to understand the ppr concept. For this i have taken 2 pictures from the sensor with the part/serial number on it which i will attach to this post. If i lookup those parts and view the specs i dont see any hard number(yet).
The sensor casing shows hb5m-50-313-ne-s-d which would translate to 50 ppr. Inside the casing there is HEDS-9100 and a codewheel. With the HEDS-9100 is cant find a hard number. Hope you can help find the right number.
Thanks in advance!
Kind regards,
Vincent
So that is 50 ppr, which is good. Enter 50 in the pulses per revolution option.
But a concern:
It needs a 5V +/-0.5V supply voltage. V+, the power output on the RPM port, is about 6.5V, so powering it from V+ would be very bad both for the encoder and for YourDyno.
The newest version of YourDyno has 5V output on the RPM sensor power pin. In that case the power pin is marked 5V instead of V+.
If your box has V+, then you need some way of providing 5V. Don't use 5V from the load cell output, since that is a specially filtered analog power supply, and the encoder is very power hungry (up to 85mA), so it can make noise on the load cell.
A separate 5V power supply is recommended, with the minus output connected to the RPM port's 0V pin and to the RPM sensor. The 5V is connected to the sensor only. Do no connect V+ to anything.
Hi there!
Thanks again for you very useful feedback! By this time i have changed the 5v feed from V+ to an external supply as by your advice. This does create a working situation. But, to bad, it does not create a solution for the rpm drift. For instance, i use the tacho function to set the rpm at 2000. Then i use the steady state function with the brake set at 2000 rpm and slowly go to 5 psi of boost i will and up at 2200+ rpm.
Maybe you have any further idea's?
Hope to hear from you.
Kind regards,
Vincent
Hi,
So the RPM is ok now?
If the the brake adjustment is not aggressive enough, then you need to adjust the PID parameters. Ki and/or Kp need to be increased.
Hi there!
Did not get to ramp runs yet. More doing steady state to map a car. I will increase the I and P a bit tonight to see if the drift is less. Thank you a lot for your assistance this far!
Kind regards,
Vincent