Jump to content

Calibrating The Oil Pressure Sensor


nelmo

Recommended Posts

My oil pressure gauge has never worked properly - it always shows a value off the scale. I've been told to send the sensor (or gauge?) off to be calibrated but i was wondering if this was a DIY job?

 

My feeble grasp on electrics suggests a load resistor in the signal wire from the sensor should bring the current down to a level that the gauge can actually display.

 

I've used a standalone oil pressure gauge so i know what pressure i get at idle - if i experiment with a few different resistor loads, does this sound feasible?

Link to comment
Share on other sites

Electrical gauges need to run off a stabilized supply, often 8 volts.

If connected to the 12 to 14 volts from the battery they over read.

A resistor can work but the gauge reading will vary a bit with battery voltage.

This is why the fuel gauge is always operated off a stabilized supply.

Link to comment
Share on other sites

I don't mind about the needle wandering about a little, i just want to be able to tell that i have some pressure.

 

Out of interest, where do we get a stabilised supply from in our cars? I have the standard GBS loom - is there something built into that for the fuel gauge?

Link to comment
Share on other sites

If you go down the calibration route, to ensure it is done accurately you'd have to calibrate the whole loop, sensor, cable & gauge.

It's no good doing one or the other (or both) as you may have a potential unknown voltage drop between the two in your loom, causing errors.

 

If you have standalone gauge, couldn't you do a comparison at varying rpm (almost like spot calibrations) via a temporary 'T' piece, this will give you a known offset to apply.

Simpler than trying to find a suitable resistor or full calibration (& cheaper)

Link to comment
Share on other sites

Value off the scale usually means the sensor isnt earthed to the block properly, did you use ptfe tape or sealant?

Also check wiring for continuity

 

I did have a gauge that had wires transposed same reading off the gauge as a bad earth

Link to comment
Share on other sites

Other option is to buy a calibrated sensor first-off. KA Sensors would be my recommendation. You get a spec sheet with the sensor showing voltage range and calibrated pressures at specified voltages (or temperatures/etc).

 

But then you need a specific gauge of course, or something that can be adjusted to match. So it's all a bit high-end really. Most of the time you just want to know a ballpark figure - is there any oil pressure at all :) I don't care whether it's 15 or 20 psi, as long as it's not 0 :)

  • Like 1
Link to comment
Share on other sites

Fit a mechanical one, easy to do and reliable. I couldn't find one that matched the rest of my gauges so I put it in a little housing and stuck it to my transmission tunnel under the dash with double sided gorilla tape until I had a better idea. Still there a year later.

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.

Guest
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.

Loading...
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...