924Board.org

[Rhubie]

Im pretty sure if I look ill find it, but just to stay safe where is the metering screw?

[Paul]

It applies pressure to the metering plate arm. You will need a long allen wrench.

https://tse3.mm.bing.net/th?id=OIP.OK0EjKMzX3TUQZRvgRZp8gEsDI&pid=15.1

Its labeled "idle mixture adjustment screw" in the above diagram.
_________________
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.

[Eric P]

Unless somebody messed with the metering screw, it shouldn't be out of adjustment., or at least very far. Keep track of how many turns you put on the metering screw so you can go back to where you started if need be.

If that fails: Inside your fuel distributor, there is a piston that moves up and down with the flow sensor plate. The piston opens and closes fuel ports in a small sleeve or cylinder in the fuel distributor. These ports have an o-ring that seals the sleeve to the upper half of the fuel distributor. It sounds complex but is surprisingly simple once you see it. Here is a picture of the o-rings in question:


Photo taken from this thread:http://www.924board.org/viewtopic.php?t=24789

If your car has been sitting for any length of time, there's a probability that these o-rings are cracked and torn and need to be replaced. Three out of four of my o-rings were ripped when I bought my 924. A lot of people will tell you not to tear into the fuel distributor, but I disagree. Even if you're meticulous (and you should be when dealing with fuel systems), it should only be a 20-30 minute job. O-rings were not designed to last 35+ years and replacement will need to be done on all these cars eventually.

It ended up costing me about $10 to fix mine after buying a handful of o-rings and a bottle of indian head shellac to reseal it. It's also a good chance to clean all the crud out of your fuel distributor that has accumulated over the years. Mine had a lot of black crumbly stuff that fell out. I'd hate for that to get into my injectors.

Please note: if you take the fuel distributor off, do NOT drop the piston. It's machined to very close tolerances. If the piston drops, chances are you'll need a new distributor as the piston and cylinder are matching pairs and are not interchangeable. There is nothing holding the piston in once you remove the distributor, so keep your hand under there to hold the piston in when you remove it from the car.

Or you could send it off and pay $500+ for somebody else to rebuild it

If you decide to have at it, I can give you more tips. It isn't very hard at all if you have a basic mechanical understanding of how it works. There are a few good youtube videos that describe it fairly well if you're curious.
_________________
1980 924 NA, US model
1987 924S, US model

[Rhubie]

So I think i'll dig into the distributor just for safe measure considering I need to drive this thing 300miles in augest for moving. I will also fiddle with the arm just to make sure the previous owner didn't do anything stupid to it.

I have an idea of the type of o rings

8mm x 2mm four of those

14mm x 2mm and that one on top right? Viton too?

And that piston... Drop it on the floor or? Little confused and don't want to drop 500$

[Rhubie]

Okay.. after some research those o rings help regulate the amount of fuel given to the engine based on the MAF and the amount the arm moves due to air flow.

Correct?

And because they are cracked/shrunk due to age, they leaked fuel constantly allowing the injectors to spray without the MAF.

Correct?

[Rhubie]

That would also explain the very small resistance the pressure plate gives off

Explains that