1983 944 - Throttle bounce at idle + other questions.

[superjario18]

Howdy all,

Its the time of the year when you sort out some of the issues you've had over the winter months right? Right...

Well, I have one that's been plaguing me for a bit. It was stalling at idle, found the intake gaskets were shot, replace those... Now at idle it bounces, it'll drop down to ~700 rpm catch itself (the oil pressure also drops to about half of what it normally is)
Then it bounces up to about 1400~ rpm and repeats this process but never stalls.

There was a rip in the intake boot which I got a new one and replaced it, also cleaned the TB and MAF while I had em apart just in case. Upon removing the intake boot I saw some oil resting in the bottom of the throttle body lip as seen below.




Now my question is, where does that pipe with the green arrows pointing at it go? That's where the oil is coming from.

ALSO, what would you suggest checking on to get the car to idle correctly again? All input is appreciated and I'll be checking this thread back often.

Thanks in advance!!


*edit*

I also have a small list of things I was going to do since they are unknown to me when it was last done.

Control Arms + bushings
bigger sway bars + bushings
Belts
new OEM intake gaskets for gasket paper made ones
Oil pan gasket and removal to clean it up a bit (more visual and to make sure there is no sludge)

I was thinking this could be a vac issue, so I was going to get a vac diagram and replace all of the stuff with new hose which wouldn't hurt anyways.


http://forums.pelicanparts.com/porsche-924-944-968-technical-forum/515009-idle-stabilizer-valve-testing.html checking this out, cause of some of the suggestions. the OP seems to have the same symptoms as me with his being broken... man if this is it... lol

http://944foot2thefloor.blogspot.com/2010/10/erratic-idle-problem-porsche-944-square.html This as well

[Gawernator]

Sounds like vacuum... Wouldn't hurt to test the ICV and TPS. Is your vacuum hose replaced with plastic tubing connected by electrical tape?! The metal tube goes into the side of the J boot

[superjario18]

Originally Posted by Gawernator

Sounds like vacuum... Wouldn't hurt to test the ICV and TPS. Is your vacuum hose replaced with plastic tubing connected by electrical tape?! The metal tube goes into the side of the J boot

No a PO rebuilt the engine I guess... and he did it all in red and blue, including blue wire covers.

I know that goes into the J boot, but where does it come from on the engine?

ICV and TPS can't hurt to check so I'll do that.

[Chunkerz]

That pipe goes to the ISV. When you have the intake off check the hoses to/from it for splits, especially at the bends.

[superjario18]

Originally Posted by Chunkerz

That pipe goes to the ISV. When you have the intake off check the hoses to/from it for splits, especially at the bends.

Good info!! Thanks!

[Garo156]

I just got done redoing my 83 in the upper end and there are a few things you need to sort out. First, make sure all vacuum lines are secure and not split our cracked. Next make sure you replace the AOS seals I'd you are getting oil in the throttle body and air box. Go ahead and rebuild your throttle body with new seals because the oldones disintegrate and cause a vacuum leak. The 83 does not have an idle control valve, it has an auxiliary air valve and it can be cleaned with brake cleaner or throttle body cleaner. Also make sure your number 1 intake gasket is in the correct orientation be cause if it is wrong it will block the flow of fuel from the injector. torque to proper spec so gaskets are even with no vacuum leaks. New gaskets at AFM and air box. In short, if it is rubber replace it. Any more questions, please feel free to pm me.

[Gawernator]

No disrespect to chunkerz but the hose on the other end of that pipe is the AOS breather hose, I just replaced mine recently. It goes to the top of the air oil separator.

[superjario18]

Originally Posted by Gawernator

No disrespect to chunkerz but the hose on the other end of that pipe is the AOS breather hose, I just replaced mine recently. It goes to the top of the air oil separator.

So if my AOS is going it'll cause stuff like that (the oil)? (not familiar with the AOS), is that something that can go bad and needs replacing? If not whats the best to look at? Just the hoses?

Also Thanks Garo156, I was thinking I should replace all the rubber, but I might as well if i'm going to be in there doing other stuff. Time to find a list of all the specialty rubber that needs replacin...

[Gawernator]

Garo told you to replace AOS seals. That's the same exact thing we are all talking about. The two seals go bad over time, start leaking in oil which gets sucked up the top into that hose, into that pipe and eventually into your J-boot, air filter box and intake manifold. The solution is to replace those two O-rings.

[Volhv]

Originally Posted by Gawernator

The two seals go bad over time, start leaking in oil which gets sucked up the top into that hose

The o-rings don't leak in oil, if anything they leak it out. But what they do leak in, if outside air. This extra air is being pulled by the vacuum hose at the top of the AOS, and the "turbulence" causes excessive atomized oil to go in the intake.... via the breather hose. For it to work as it was intended, the engine must be sealed up nice and tight. At least that's how I can explain the phenomenon, If I happen to me mistaken, I would appreciate a clarification.

Oh, and there is one more seal in the AOS...... It's not in the PET.