1983 944, manual

okay i ripped the engine bay appart today getting at the AC compressor,

learned alot of cool things, sometimes the porsche design is genius and sometimes it makes me want to kill whoever designed it..

anyway

everyone's favorite topic, HOSES AND VAC LINES

i need EXPLANATIONS, either personal, or external links, as to why stuff goes where it goes:

here is what i drew up, tell me if i'm wrong, and answer some questions for me.

there are two parts to this diagram, one relating to the hoses that work off the Intake Manifold

and the other part of the diagram is the system that works of the big "?" thing,

so:



IM = intake manifold
ED1 = electrical doo-hickey 1
ED2 = electrical doo-hickey 2

set of questions:

note: i realize that probably the most important part of this is the vacume needed by the brake booster, i understand that but what the hell is all the other garbage

1. after ED1 and ED2 the hoses wind up in what appears to be the vicinity of the oil seperator, where exactly do they go, and WHY do they go there?

2. what are, ED1 and ED2
3. why is there a line to the J-boot, since the system can already draw vacume from the IM


2nd part of the diagram, regarding the big "?", which is this part:


NOTE:

i believe this to be a system used for emissions purposes, to re-circulate fuel fumes and oil vapours.. maybe, i dunno, someone please confirm.

D: i guess fuel vapours from the gas tank are drawn in through D and partialy store in the charcole chamber, right?

question: what happens if i cut this off?

C: i have no clue, why is this necessary?

B: again, why? it leads to a little thing thats on top of the oil seperator, what the hell is it for?

A: i guess this is to re-distribute the fuel-fumes to the throttle body from the charcole canister and the twin pressure regulator guys,

question: can this be cut off/blocked off?

this is going to be mostly a race car and its over 20 years old so i dont care about emssions.

i can put a litte filter doo-dad on the end of the fuel tank so the vapours can evaporate.

please dont ask why i'm doing this, or tell me that i shouldnt do this, at the very least if you tell me not to do it please explain to me in detail why i shouldnt delete this or that hose.

CHEERS!

 

Edit: I see your photo now.

 

What exactly are you working on that you need to rip the bay apart to get at the compressor? I just dropped mine, replaced the bearing in the clutch, and put it back on entirely from below. It would have been a tad easier to remove the air filter assmebly to get at one of the bolts, but I just didn't feel like it because I didn't want to get into a "while I'm in there".

Not that I can necessarily help you with your other questions......

 

1. i need to replace my front bumper cuz its cracked, and i dont like it

2. i'm also changing all of the belts/pullies

3. i want to dig around and see what makes this sucker tick


BOOO

 

You still didn't tell me what year/model!!!???

And #3 is the best reason ever. Sounds like the reason for a lot of things I do.

 

word.

 

year/model is at the top of the first post...

 

I swear you must have edited that. Damn you! You did...the images are in-line now!

 

Would these help? These pics are not of my car. I collected archived them from somewhere in the event that I need them in the future. I hope they will be useful for you.

 

Good luck with everything - I do highly reccomend the Lindsey Racing silicon vacuum line kit.

 

There's a vacuum routing diagram and description for the 1985.5 and newer cars at Clark's garage:
http://www.clarks-garage.com/shop-manual/fuel-13.htm

It's going to be somewhat different from your car, but it's a start. This information
is in the factory workshop manual, and I think it's also in the owner's manual.

 

no i realize where all this information is

what i cant seem to find is WHY these components are where they are, what is their function, how will the car function without them, and if it functions poorly what has to be done to adjust for lack of a hose or two (maybe some DME tuning?)

i have read and re-read all those diagrams over and over, to me "shut off valve" and "control valve" could very well have been written "rock off valve" and "discontrol valve"

you know?

 

thanks but..

whats a cycling valve?

what is a venturi?

 

Looking at the second diagram, it seems to me the major function of those controls and hoses is to regulate the flow of gasoline vapors from the charcoal canister where they're stored, into the intake manifold.

If you disconnected hose D, for example, then the gasoline vapors from the charcoal canister would be vented to the atmosphere instead of being drawn into the intake manifold. The effect is that your car would pollute the atmosphere more than it ordinarily would. The car shouldn't run worse since the engine vacuum isn't affected, but OTOH it doesn't really make sense to cut the hose since it's not hurting performance.

Now since Hose D has the gasoline vapors, it's got to continue somewhere, and my guess would be Hose C, again based on the second diagram from Clark's garage. Looks like a vacuum signal is applied to hose B when the engine temperature is above 58C. The big ??? is probably a valve that regulates the flow of vapors based upon the vacuum signal B.

To figure out how this valve works, you could remove the hoses, apply a vacuum signal with a Mity-Vac pump to Hose B, and use a compressor to blow a little air (1-2 psi perhaps) into Hose D.

Looks like Hose A is a vacuum signal -- don't cut it since your engine will probably run like crap.

If you're trying to understand how this stuff works, why not consult a textbook? There's nothing special about the Porsche engine in this respect.

 

Austin is correct those valves along with the rabbit ears on the coolant hard pipe at the back of the cylinder head all control the flow of the fuel vapors and when that happens. They arent really central to the engine running, they just look complex.