924Board.org

ReMo · Joined: 14 Jul 2008 Posts: 18 Location: Netherlands

Hello i'm from the Netherlands so forgive me my poor englisch.
I still have a problem. The idle speed of my 924 2.0 ('81) was to high. The mechanic told me that in the venturi tube (petnr. 035-133-753-A) has to be something likes a piece of sponge. By my car that piece was missing so he gets to much air.

Can some one tell me if he is right?

He fixed it with a plastic cap with a little hole.

Martijnus · Joined: 29 Dec 2006 Posts: 2019 Location: Netherlands

Haven't seen that thing before... where does it go? in the intake system?
_________________
"Rule: Turbo's make torque, and torque makes fun." (C. Bell)

924 "50-jahre", 1981.
MSII/extra, LPG, ITB's, 5lug.
To be turbo'ed in a while.
Killed her at the Nurburgring, Porscheless at the moment

ReMo · Joined: 14 Jul 2008 Posts: 18 Location: Netherlands

It comes from the airfilter to the fuelhouse? en makes the vacuum on the brakes.

Ozzie · Posted: Mon Sep 22, 2008 11:25 pm Post subject:

Mine doesnt have a sponge and is straight through.
Make sure its the correct way around or it will affect brakes.

Too high idle is caused from timing, idle screw or air/fuel mix or combination of all 3.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

Rich H · Posted: Tue Sep 23, 2008 1:57 am Post subject:

I would think it will be a vacuum leak somewhere, could be there, but not likely, more likely to be the Auxliary air valve, one of the big rubber boots or injectro seals leaking air.

Martijnus: How are you working your brake servo with TBs?
_________________
1994 Lotus Esprit S4 - Work in progress...
1980 Porsche 924 S2 DITC Turbo - Original spec
1978 Homo-Sapiens - Tired spec
1953 Landrover S1 - Pensioner Spec

Ozzie · Posted: Tue Sep 23, 2008 7:11 am Post subject:

Any vacuum leak will mess with the air fuel mix.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

Martijnus · Joined: 29 Dec 2006 Posts: 2019 Location: Netherlands

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

ReMo · Joined: 14 Jul 2008 Posts: 18 Location: Netherlands

There are no leaks at all in the air/vacuum system. Yesterday i removed the plastic cap the mechanic placed. The car's idle is 1050 r/m.

I will ask if they can adjust the CO. The problems that i have is that the car will not start good enough.

Martijnus · Joined: 29 Dec 2006 Posts: 2019 Location: Netherlands

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

Thanks for the info! Looking forward to any pics, I'll check msefi for some info too.
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1987 951 - M193 Version for Japan

Martijnus · Joined: 29 Dec 2006 Posts: 2019 Location: Netherlands

pics on msefi were dead iirc.

I was sure I had a pic of the seperate thing, but I guess I lost it during formatting my uberlame camera.

Found a pic with it still mounted on the engine, hope you get the idea:

the thing beneath the tb's.
_________________
"Rule: Turbo's make torque, and torque makes fun." (C. Bell)

924 "50-jahre", 1981.
MSII/extra, LPG, ITB's, 5lug.
To be turbo'ed in a while.
Killed her at the Nurburgring, Porscheless at the moment

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

OK, I think I understand.

1. Sealed tube below the throttle body intakes is the vacuum storage.

2. Hose running from each old injector hose to the vacuum storage to build vacuum.

3. Hoses running from the vacuum storage to whichever components nees vacuum.

Very neat!

Couple of questions.

What are the hoses connected to on the vacuum storage device? Are those just regular hose barbs or are they special?

Do you still run your brake booster directly off your intake manifold?

Any pictures of your injector holes handy to show the connections there?

Thanks Martijnus, don't go outside and take any pictures, just if you already have them handy. You should be resting and recovering.
_________________
1987 951 - M193 Version for Japan

Martijnus · Joined: 29 Dec 2006 Posts: 2019 Location: Netherlands

hahah thanks

I just bought the cheapest hose barbs I could get, just regular barbs with NPT thread (iirc), the hoses themselves should have some margin for fitting tight.

The brake booster is fed from the storage plenum, because I don't have a manifold and I figured it was 'faster' when 4 cylinders would provide the vacuum instead of 1.

Plus, because it's on the same plenum as my MAP from megasquirt, MS should compensate for the brake booster air

.

Still, I don't know if my idle will rise when I kick the brakes in.

I guessed about the volume, I was told some people use an old fuel filter for a plenum, fuel resistant etc...

I bought some other hose barbs, without threads, for the injector holes.. Keeping the rubber O-rings in the bungs provided a tight fit!
I guess I was lucky choosing the right barbs, but that's not that hard.
_________________
"Rule: Turbo's make torque, and torque makes fun." (C. Bell)

924 "50-jahre", 1981.
MSII/extra, LPG, ITB's, 5lug.
To be turbo'ed in a while.
Killed her at the Nurburgring, Porscheless at the moment

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

I like it! I'm hoping to finally put the new Weber kit I bought for my 924 a few years back on the car. I'm liking this vacuum idea, I could also run vacuum to my catch can as well. Lots of advantages.
_________________
1987 951 - M193 Version for Japan