erratic oil gauge

[Hawaiis0]

Strolling out yesterday and noticed that the oil pressure would go high and wobble about when applying throttle only.

Steady at idle.

I've gone back to 2013 in the searches and only found a possible similarity to dizzy rotation interfering with wiring.

I'll look at that later but any ideas above that?

[Lotus-e-Clan]

Well it's not likely to be a real reading otherwise something would be very wrong with either the drive to the oil pump or the big end bearings are spining (oil holes in the shell rotating)!

So there's three main investigation areas: -
1) loose/coroded engine earth strap.
2) loose sensor spade connector
3) fractured oil sensor wire (the short length from spade connector to the supported (bundled) main engine loom.

I can't see the sensor itself being faulty.

The positive 12v to the gauge is the other end of the circuit but unless you are seeing wildly variable volts with revs I can't see that's the cause either.

The dizzy wires are miles away from my oil sensor at least, so I can't help there.

How's your engine mounts? Is the engine moving more than it should in response to revs /torque?

[MetBlue]

Be interested how this thread develops. I've got the same symptoms. At steady speeds above around 3000 RPM, Rock steady. Tick over also steady. But normal driving around and through the gears, can bounce around all over the place, including going hard to the stops on full reading on occasions. I'd concluded a bad connection somewhere, but spade is tight on the sensor. Dash currently out but no signs of problems behind there.
Tony

[CID]

I also ended up buying a new oil pressure gauge. Apparently the internals of the gauge gone bad. I sometimes had to knock on the gauge to make it stable.
Also watch out to buy the right gauge/sensor combination. You have different scales which go with only 1 sensor.
When I bought the car the combination was wrong telling me 0.2bar pressure at idle when hot

Luckily.. my mechanical gauge told me the pressure was OK...

Rgds Curt

[MetBlue]

All gone quiet here, and as the consensus seemed to be the route cause of this issue is a dodgy gauge, I decided there was nothing to be lost by stripping down the oil gauge. Hopefully I'd find something obvious.

First step of the strip is to "unroll" the bezel, which wasn't too bad. Then from the rear I removed the nut holding the central earth spade - So far so good,.
Gauge internals seemed pretty well locked in the plastic housing at this point, and it was clear the other two electrical spades had been swagged open to lock in place, looking like they could be holding the internals.

Long story short - They don't....inside the gauge housing, both spades turns into a pin, that just push into the back of the gauge coil ( the yellow bits).
I now know that all I needed to do after removing the rear spade / nut and bezel, was to gently pull the internals out from the front.


Unfortunately there was no obvious problem ( signs of burning, loose wire or dry joints), so I've just had to rebuild, not expecting any symptoms to have changed when I test it.



Nothing ventured, nothing gained as the saying goes.
But at least I know what needs to be done ( and more importantly NOT DONE) to get at the workings of the smaller dial gauges.

Tony

[Hawaiis0]

Its a bit of a strange one here.

The gauge was steady at idle and erratic when driving power on.

However, now when stationary today the gauge was steady all the time - idle or pedal power on.

I have though just had the dash out to fix a broken fuel gauge light and might have disturbed something.

Going for a run out tomorrow so will monitor

[DavidOliver]

As previously indicated, I can only recommend a mechanical guage, very easy to install and not expensive, check Merlin Motorsport for types and prices.
Any reading is what you have got, great peace of mind.

Dave the cog.

[MetBlue]

Well I'm pretty sure it's the gauge, as yesterday dash temporarily fitted, engine not started, but gauge went randomly full scale when ignition turned on ( I was checking polarity for LED panel bulbs I'm fitting).

Tony

[Lotus-e-Clan]

Need to substitute the gauge for a known good one to be sure.

If the temperature gauge sensor had a similar resistance profile to the oil pressure gauge, then substituting the two gauges would shed more light on the issue. That is, you'd expect the oil pressure gauge to still act randomly when connected to the temp sensor - if the oil gauge is faulty.

Alternatively, connect the gauge through a suitably sized resistor (value equivalent to the sensor's zero value) and observe the stability of the gauge.