[urq] [Bulk] Re: Oil pressure warning at 2800 rpm, 1988 90Q

[tlum at flash.net]

Hi Steve,

Only 1981 MY 4000S had the gauge sender with the 0.3 bar switch.  All later Audi gauge sensors have a 1.8 bar switch.  I'm using a 1981 sender in my T43 5000S because the block only has one place for the switch.

Tony


= = = Original message = = =

I would expect the switch in the pressure sender for the gauge would be used
as the low pressure sender ... that is how most similar sending units are
set up.  The high pressure sender would be the one on the spark plug side of
the block.  This sender is also reverse logic from the low pressure switch,
it is open at low pressure and closes at higher pressure.  I suspect that
the circuit to the high pressure sensor is open or the sender is bad, this
would cause a situation where the monitor module is expecting to see the
switch close, but it never does, and you get the warning at higher RPMs.  

If you have an oil pressure gauge it does tend to make the high pressure
monitoring module of little use ... 

Steve Buchholz

-----Original Message-----

> ...  It gives me a loud beep and a
> flashing oil pressure symbol every time I exceed 2800 rpm or so.  The
light
> stays on as long as I keep it above 2800, disappears only if the engine
> slows down.
>

BTDT


> My understanding is that there is a low and a high pressure sensor on the
> car, but looking at the engine block I only see one, brown.


There are 2, one above the other, both screwed in the block.


>  Is the pressure sender (the big barrel) acting as the high pressure
> sensor?  It's disconnected right now, actually the terminals broke off due
> to rust, awaits fixing.
>

IIRC, the 2-wire is the high pressure, the single wire is for low pressure.
Huw can correct me

>
> I would greatly appreciate some sort of reassurance that it's the
> sensor, rather than actual low oil pressure!
>

It was in my case.  It is important to get a new one with the exact same
part number and rating - there are 2 pressure ratings listed on the
regulator.  Otherwise  the light keeps on coming with new regulator.
Several kinds were used as seen, for instance, at <autohausaz dot com>
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