Oil pressure gauge reading off the end - too high end.

[5.0 ED]

Before i start playing around and pulling everything apart to find it i thought i'd pose the question on here, it seems i have a bad earth somewhere, its causing my oil pressure gauge to go from around 6 to off the end of high side of the gauge, Its done it for a far while now, i've redone the normal earth points under the airbox, which normally cause issues with it (normally a low reading thou).

Until now i haven't bothered with it cause its only a gauge, but in testing and tuning it, i've had this issue of my tune changing, just like the flick of a switch. And tonight i notice that it happens exactly as the oil pressure gauge changes reading. When the gauge goes higher the car run's leaner.

Anyone heard of this before?

[EvilChief]

high oil pressure can be caused by sticky/faulty oil pressure relief valve, or a malfunctioning oil pressure switch/sender, but has no direct effect or influence on the tune

[5.0 ED]

nah mines definetly electrical. Use to always to go low sometimes and then i fixed the under airbox earths and now it goes high instead.

[EvilChief]

earths to engine? earth refrence wire to sender unit?

[5.0 ED]

Yeah i was hoping that maybe someone may have had the problem before, looks like its out with the ole workshop manual and multimeter tomorrow to do some tracing, shouldn't take me too long.

Anyone with an AU want to check a voltage difference for me, i want to know what the potential difference is between the tps earth wire (black) to the car body, with ignition on and engine running.

[bodes-sh]

i had the same sort of issue on an ea years ago, turned out that the wire had fallen off the sending unit, plugged it back in and it was fine again...but i imagine you have already checked that?

[5.0 ED]

yeah i've been thru that previously, its a new oil sender and plug on it, im pretty sure from memory the AU oil sender reads low when disconnected on AU's,