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'89 200TQ: control pressure regulator help needed
In message <firstname.lastname@example.org> I6941tb@aol.com writes:
> In a message dated 96-12-16 19:06:14 EST, you write:
>> The Control Pressure Regulator is a very low tech piece of equipment. It
>> consists of a pressure regulating diaphragm valve that has a heated
>> bimetallic strip which controls the outlet pressure. On your 200Q you
>> should also have some vacuum (actually boost) lines connected to modulate
>> the control pressure as manifold goes above atmospheric.
> No, it does not have, although Bentley shows them.
The 1988 MB engine in the ur-quattro also has no vacuum or boost connections
to the warmup regulator. WOT enrichment is done by the computer.
> Fuel pressure (valve on the gage is open, gasoline flows through the gage):
> at +20C = 23psi (1.6 bar)
> at +50C = 51psi (3.4 bar)
> System pressure (valve is closed):
> at +50C = 95psi (6.6bar)
Those are pretty good, especially the 3.4 bar, which is the important one.
> So, the control pressure regulator senses the temperature by it's own body (a
> bi-metal strip) and not with a separate dedicated temperature sensor? It
Two ways - its own internal bimetal strips (2 of them) and physical contact
with the block.
>> I had occasion to disassemble one of these and found that there is a slug
>> in the side of the casting that adjusts the bias on the bimetallic strip.
> I'd like to take it apart to see what's inside. Can I reuse the whatever
> gaskets I'll be taking apart or do I need to get them beforehand?
Yup. It's sealed via a large O-ring recessed into a cutout. It's basically a
rubber compression seal - you should have no trouble resealing it. Martin
at BR Motorsport cautions that you should remove the valve from the block
_before_ detaching the fuel lines - the Allen-head screws that fix it to the
block are overstressed by the torque on the fuel line bolts. Don't forget
"clean room" conditions - make sure any petrol you use for rinsing out has been
But before you start - have you set up the fuel injection properly from first
principles, detaching and plugging the breathers, turning off electricals,
Committee Member, UK Audi [ur-]quattro Owners Club