mcholdfast

I'm hearing a sucking sound underneath the intake of the S4. I capped off the top of the MAF and blew smoke in the vacuum line from the brake booster and smoke poured from underneath the front of the intake. Before I started pulling the intake off, I did a little exploring and found this small vacuum line running under the front of the intake that had been capped off with a bolt. Does anyone know what it should be connected to? The end that is attached connects right under the cross member on the passenger side right by the front end of the fuel rail cover. I did some searching on the list and didn't find it and the valve(?) that it is connected to doesn't exist on the GT so no help there.

worf928

Not a factory vacuum line route. You'll need to figure out what the other end is connected to. Or figure out what is not connected. Plenty of sources of info including the intake R&R tech procedure on the OC website.

http://www.928oc.org/journal/page2.html

worf928

And what's up with the blue spade connectors and the thing where your TEMP-II sensor should be (or is?)

worf928

Reading again, more carefully... What valve is missing on your GT? Air pump diverter or tank vent diverter? If I was guessing I'd say that the random line is for the tank vent. That's the only vacuum line that is close to the area in your picture. However, it would be rather weird for the tank vent system to have been removed.

You'll need to figure out what vacuum consumers are NOT missing.

You have:
fuel dampers x 2 -> 5-way connector behind MAS
regulator -> 5-way connector behind MAS
plug at 5-way connector behind MAS (except on Auto tranny)
5-way connector behind MAS -> rear-facing port on top of throttle body
tank vent line -> front-facing port on top of TB
air pump -> port under throttle body
flappy source -> 4-way at check valve

mcholdfast

Thanks for your quick reply, Dave C.
Here are some pics of what one end of the disconnected vacuum line and the blue spade connectors are (were) connected to. This part isn't found on my GT or the pics in the 928OC page you referenced. I had already read and printed that procedure in prep for removing the intake. The # printed on the part is 317-731 0415 along with "Made in USA". Any idea what this part is and where the vacuum line should go that is coming out of the top of it? This is a ROW car if that could make a difference.

worf928

Very little clue here. That gizmo looks similar to the solenoid for the flappy. Except that it's on the wrong side of the engine bay. Do you see a similar looking thing on the driver's side bolted to the belt cover?

The gizmo from your picture has two vacuum connections. One (obviously) is plugged. Any idea about the other connection?

If I had to guess, with a gun to my head, at this point...

1) Your PO broke the flappy's solenoid.
2) He was too cheap to pay $$ for the Porsche part.
3) He was smart enough to find a similar part.
4) He wasn't motivated enough to transplant the bracket from the factory part to allow OEM placement.
5) He cut the harness connector for the solenoid off of your very inexpensive (not) LH engine harness and butt-spliced spade connectors to fit the non-OEM part, along with an extension for the harness since it's too short to get to the other side of the engine.
6) After the above fit of absolute brilliance he discovered that the other end of the vacuum line snaked under the intake and gave up.
7) Your flappy doesn't work.

(Trace the spade connections - if they go to the fuel injection harness on the driver's side then that's further evidence of the above.)

Sorry for the acerbic tone above. It's been a long day and I've seen too many eff'd up harnesses in the last few weeks to not want to pistol whip anyone that cuts the head off a harness rather than make an adaptor or buy the right friggen' part. Once you cut the harness there's no going back. And replacements are NLA or $$$.

I hope my guess is wrong. And I don't want a prize if I'm right.

worf928

Wait a minute. What the heck? The gizmo in your picture has THREE connections. The flappy solenoid has two. So.... if my above theory is correct, then the third input of your gizmo must be plugged. One input goes to the 4-way and the other goes to the flappy. Which is which? You'll need to get a vacuum pump. The connection that holds vacuum goes to the 4-way. The connection that bleeds vacuum goes to the flappy. 12v on the spade connectors should reverse the behavior of the connection to the 4-way. (If I'm right and you do not have the factory flappy gizmo bolted to your driver's side belt cover. Look at your 90's. The vacuum and flappy stuff is the same as a non-messed-with GT.)

Good luck.

worf928

Lastly, as far as I know ROW vacuum system is the same as USA. It gets interesting with RHD since the brake booster is on the other side of the engine.

Do you know exactly for what part of the ROW your car was originally manufactured? Might buy us a clue.

Leon Speed

Looks like vacuum router - switches vacuum between the two bottom connections. Also it looks like it acts based on a certain temperature in the cooling fluid. Still..no idea what purpose it serves..

mcholdfast

The flappy solenoid is in place on the driver's side belt cover in the first pic below. Notice the missing vacuum line on top. One of the wires from the gizmo connects to the solenoid. The other wire connects to the temp sensor beside the gizmo shown in the 2nd pic. The other two vacuum lines from the gizmo run along side the passenger side valve cover. One disappears behind the valve cover and the other connects to the vacuum regulator(?) under the air tube as shown in the third pic below. The car was originally built for Saudi Arabia. Does any of this help solve the mistery?

worf928

I was just looking at a flappy solenoid. It also has three connections - just that on the stock part one connection is permanently capped. In your GT picture it looks like the cap is missing? Or perhaps is another clue.

I'm glad that my theory was not correct: your flappy gizmo is in place.

Not yet. But, we know from where to buy a clue. Also, your latest pictures give a better idea how things are/were/might be hooked up.

SA cars had some kind of dust trap in the air tubes and something, IIRC, to help cope with the ridiculously high average temps. PM Jim Moorehouse (assuming he's fixed his drive issue) and see if he's got any S.A. info that he's been saving up. Have you done a search on S.A.?

I'll poke around in PET later and see if I can find anything S.A.

mcholdfast

Thanks Dave. All of the pics are from the 90 ROW S4. The GT does have a cap on the top nipple of the solenoid. I assume that the ROW S4 should also have a cap since nothing was attached to it. I'll send a PM to Jim M. to see if he has any info. Meanwhile I'm going to start pulling the intake off tomorrow. I'll start another thread to see if there are any locals willing to lend a novice a hand or at least some wisdom. Wish me luck and thanks again for your help.

Leon Speed

So, to recap: the gizmo is not intended for the flappy valve (you do have to cap the flappy solenoid though). The gizmo either opens or closes above 3600 rpm with either a warm or cold engine. This triggers the air pump crossover valve and something we don't know because that vacuum line was capped with a screw. Btw it does'nt look factory to me so don't think it has something to do with SA.

mcholdfast

I wonder if it is something that was added during federalization?

marton

Must have been to start the turbo; pity they removed it

Marton