VDO sensors

[david oleary]

Just wondering??
So i replaced my VDO sensors because i have different readings on my AIM dash vs the readings i have on my inline pressure gauge,
So the VDO shows 51 lbs of fuel pressure ( 3 different VDO sensors new from Germany) the inline gauge shows 56 lbs (3 new pressure gauges) so i wonder what i really have???
Has anyone seen this before???
GSXR 1000 engine

[David Ferguson]

I bet you have closer to 56 psi.

If you ever look inside the VDO can, you will find a bent brass tube that moves a wiper along a curved wire wound track. So it's counting on the pressure to straighten the tube and provide the correct resistance.

It's amazing they work at all in the vibration on a race car. I think they are only accurate to about 4-5% of the full scale reading -- so a 100 psi sensor could have a 5% error. But you found 3 that read the same -- a miracle.

We used to buy those 10-20 at a time and sort them by how close to the target 10ohms at zero psi they were. We put those onto systems where you couldn't zero the sensor -- so the customer would get a zero reading. Otherwise they might see +/- 2psi when the engine was stopped.

Solid state pressure sensors have an accuracy of about 0.5% of full scale, so a 150 psi sensor is good for .75 psi accuracy.