starts but will not idle - What did I mess up?
 

Hiya. So my 89 2.7l 944 ran about a week ago when I parked it to clean the engine up and fix the vacuum leak I had that was causing a rough, but very driveable idle. Below is a list of what I did, something in the list is causing the no start.

-Cleaned up the engine as well as I could with degreaser, soap, water, etc.
-Removed intake, intake manifold and cleaned everything up.
-Removed fuel rail, installed new seals on injectors.
-installed silicone vacuum lines.
-checked compression (all cylinders reading about 150psi)
-Cleaned up spark plugs
-Installed new ignition rotor

I think that about sums it up. Now the car will start and fire up but dies within a second or so. I can give it gas to keep it going but it is very rough and upon giving it gas the revs hang and come down slowly then it will die right away.

The injectors are fine as I tested them all. The filter and everything else has been cleaned. Vacuum lines are all hooked up right from the handful of diagrams and help I have had but the blue/black thing near the rear of the engine has no where to hook up to. I was told it attaches to the brake booster via a vacuum hose coming from the attachment that also has the thick rubber hose running to the intake but I have no small vacuum hose attatchment coming from that piece. Very strange. Anyway, that wouldnt likely affect the idle but I do need to figure out how that piece hooks up. Spark is good. I'm getting plenty of fuel to the rail as far as I can tell because I tool off the test cap and upon starting fuel sprayed everywhere. No smoke of any kind. Lots of popping from the intake and intake manifold.

Maybe the TPS or the ICV? Everything worked just fine a week ago. I really only messed with the injectors (to reseal), the vacuum lines (to replace) and cleaned the engine. I'm thinking that maybe something became wet that should not have been and shorted out but the battery was removed and kept out days after washing so I'm assuming everything would have dried up in this near 90 degree weather we're having.

Seems to me like a fuel starvation issue, acts almost like the old bikes I've worked on that need the carbs rebuilt but the injectors are fine from my tests. Maybe some vacuum issue? FPR? Everything is clean and easy to locate so I cant see what I could miss. Ideas?

Thanks. :0)

UPDATE: Was able to start the car and have it idle but only if the AFM, TPS and some blug plug just below the intake are unplugged. The rpms hang at about 5k without touching the gas or anything once it starts up. By plugging in any of the 3 plugs the car starts to die right away unless you unplug them quickly.

My problem seems fairly specific so I'm sure someone out there can figure it out. Thanks for your time :0)

It sounds like you still have a vacuum leak to me...

Thanks for the response. I'm suspicious of a vacuum leak as well but everything is hooked up according to the digram save for the blue/black valve thing near the firewall that has one end going to the vacuum canister. Because it goes directly to the canister I feel it is keeping the system from creating a vacuum as the other end is not hooked to anything but I do not know what to hook it up to.

Let's see if I remember.....the vacuum starts under the intake manifold aqnd goes through an idle control valve then it runs up to the master cylinder on one side and the other branches off to the fuel rail...

According to the vacuum diagram here:

http://forums.pelicanparts.com/attachments/porsche-924-944-968-technical-forum/9767d1044846185-vacuum-diagram-na-vacuum.gif

I have everything correctly hooked up. The only thing it does not show is the diagram for the blue/black valve thing unless I misunderstand the diagram.

So you have the late '85 model?

I have an '89 2.7l but it should share the same vacuum set up as the 85.5+ Still stuck with a non running door stop. I can always start replacing everything until I get it going but that is costly and time consuming as I have to order all the parts when I'm sure it is something simple. Hmmm.