neilh

In the first of the 3 diagrams i sent you above, ONLY line 6 goes to the brake booster connection 26 . Check you have the correct lines on the cruise control reservoir. The booster connection is 26 in diagram below, make sure 24, 25 and 27 are also correct.
Do you have the workshop manuals? If not down load from :

http://www.2010.cannell.co.uk/manual...s_porsche.html

scroll down for the 928 section, you need to study section 1A group 24.....

RobbieStrosek

all seems to be in order, only 11 goes to the carb in my situation...
27 if red goes to an pot and the otherone (black) goes inside..

neilh

I assume you mean 11 ( which is the mechanical connection from the tempostat tank) goes to the throttle linkage, it is not an air line. Is the 'Y' from line 24 to the 4 way broken, its a common failure. What part are you calling a 'pot'?

RobbieStrosek

The red vacuum hose according to my picture..don;t have a clue whats that called sorry.

Btw could a vacuum leak inside, behind the dash cause this idle stall problem ?
Funny thing is i never touched anything .

When i have the engine running for a few seconds vacuum builds up...
when engine is not running i pul one hose from the 4-way connector and i hear it sucking air, so i asume a vacuum is build in that system.

neilh

The suction at the 4 way is a good sign.
I would pull the line going into the car and plug it, and the line to the heater control and plug it, also the lines going to the tempostat and plug them..

Leave only the red lines in the first diagram connected, they are all you need to get it to create vacuum to run. Also check the metal line coming off the front of the main metal plenum. It goes to the auto transmission, if it is broken you will also have a leak.

I have an identical 84 euro here, i can take a look tomorrow and see if anything else is obvious.

RobbieStrosek

thnx again neilh.
so in fact just pul the main hose small one from the breakbooster and plug it.
then see if it works with only the fuelvacuum system connected.
but this vacuum comes from the carb system.

neilh

Robbie,
Correct, that should take any leaking or miss-placed vacuum lines out of the problem. Oh, its not a carb, its a fuel injection throttle assembly
Neil

RobbieStrosek

Hehe Sorry Neil :0 need to learn a bit more about cars, last work i did was on a Opel GT from 1972 ..

Leon Speed

I am not familiar with your model year, but I see a loose two-pin connector coming of the engine harness. Right side (as seen from the front), near the firewall, brown wire, white connector. CPS, TPS, ISV?

neilh

Air temp sensor in air filter box, should not be the cause of this problem.

Leon Speed

Didn't know it existed. Is that part of the cold start injector system?

neilh

Aryan, on 928S not S4.
Also called Temp 1 or Intake air sensor,
Measures intake air temp and retards ign timing when air temp is to high.

GlenL

Have you done a smoke check?

Just like it sounds: blow smoke into a vacuum line and see there it comes out. A bad cigar will work nicely.

Really helps find those mistakes on reassembly when you are sure it's right.

Leon Speed

Cool, thanks for the info.

rexpontius

Problem solved :-)

I helped the OP to trace down the problem to the connection between the throttle-body and intake spider.

thanks for all the input!