924Board.org

[MrKrik]

so my other thread main topic is a lil vague so i made a more proper one..

So far issues coverd and checked

- timming
-cam timming
- vacume leaks
- Low compression
- binding metering plate

all Have been ehcked out adn atre oporational.

my guess so far is teh WUR as the previous owner stated he rebuilt it himself . but i cant test that theroy till i find a good used one . casue its pretty hard to lift the metering plate by hand even when teh fuel pump is on so to me that says over heigh control rpessure

77 924 NA

[Ozzie]

The WUR (control pressure regulator) is not the only pressure regulator. There is also the system pressure regulator in the fuel dist.
The WUR can only operate with a maximum pressure set by the system regulator so even if faulty or closed the pressure is set by the other.
I'd be checking the one in the fuel distributor first.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

[Smoothie]

Control pressure equals system pressure minus what's bled off by the WUR, so MrKrik's correct in thinking that the WUR could be the problem. (If the WUR's stuck closed or not bleeding-off enough pressure, control pressure would be too high, limiting movement of the air metering plate.)
_________________
"..it's made in Germany. You know the Germans always make good stuff."


'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

[MrKrik]

so then the internal regulator is jsut that lil tiny hole in the fuel distributer that runs from the control pressure inlet to the fuel return side .. where the screw with the spring and ball valve style system is locatred..
if that was stuck i guess control pressure would spike as well


i wonder what would happen if i back the distrubuter regulators spring screw out lieka wastegate

[Paul]

Buy or borrow a CIS pressure tester before doing any further guess work. In the long run, it will save you money.
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

[Ozzie]

And if system pressure is 7bar or higher? The wur would have a hard time dropping the control pressure down to a normal level.
Agree with Paul about the pressure tests.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

[Smoothie]

Absitively, check it with a CIS tester to see what's really going on.
Here's <click> a diagram showing the pressure regulator and fuel flow through the FD. I added little arrows within the fuel paths to show flow directions. The #7 more toward the lower-right is where fuel enters the control pressure area. That fuel comes from a system (aka- primary) pressure area. The WUR's job is to bleed off some of that fuel from the control pressure area, lowering it to what's obviously called control pressure. If your WUR is blocked or in any way shut off, you'll have system pressure instead of control pressure in that area above the control plunger (aka- fuel metering rod, whatever) and that will limit movement of the air metering plate.
-But, the air metering plate should move easiest after the engine's been off for while and pressure's been released. Once you turn on the fuel pumps, the system gets pressurized and the air metering plate will have some resistance. The resistance should remain, but be lesser with the pumps shut off, then as pressure leaves the system gradually over an hour or so, the plate should move easily again. If it's hard to move with the pumps off and no pressure, you more likely have a mechanical problem with the FD - it's either gunked-up (varnished) or the control plunger is mismatched to the bore. (If the PO fixed the WUR maybe he also "fixed" the FD? ) Of course if the plunger is sticking in its' bore, the air metering plate will have resistance when you lift it, then will flop up-down easily because the plunger will be stuck high-up in the bore.
If you find the plunger isn't sticking and the plate is hard to move with the system de-pressurized, Then you're left with the probability that the air metering mechanisms' pivot point is sticking...

How do you know the air metering plate isn't moving while the engine is running? Aren't things like the air cleaner in the way? -Or are you able to see it with some pieces removed?
_________________
"..it's made in Germany. You know the Germans always make good stuff."


'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

[MrKrik]

yeha i took the air filter off and watched teh plate to see if it moves . im gonna borrow a CIS tester this week sometime thanks guys