Tails

Worf928,
As promised I inspected my RHD 1990 928S4 vacuum set up and I can confirm the following.

The 4 way vacuum piece on my RHS vehicle is as follows:

1. One line connected to brake booster via a non-return valve, with the brake booster located on the RH side of the car.
2. One line (grey) connected to resonance valve (flappy valve) soleniod valve acutuator, this gray line connects into solenoid valve via the axial in line port and runs along the side of the RH fuel rail, the line to the resonance valve is at right angles to the centre axis of the solenoid valve and exit at the top.
3. One line (grey) is conneced to the vacuum reservoir located under the LH side fender or my RHD car (note: cruise control and the adjustment of the head lights are electrical controlled on my car), so this reservoir, I believe, is just a vacuum reservoir (accumulator) to maintain constant vacuum without surgers/fluctaations.
4. One line (black) is connected to the HVAC system and there is one line (white) returning through the fire wall for the activation of the heater control valve from the HVAC system.

With regards to the vacuum line to the idle stabliser valve, I believe you are right ,as I have a white line which passes under the inlet of the throttle valve in the general direction of the Idle Stabliser (unable to determine the source, however, the other end is blanked off and the blank piece is lying adjacent to the after end of the RH side camtower cover.

Your assessment of the 7 way connector is correct and I believe that ColinB set up for the GT would have of the seven outlets blanked off.

Tails 1990 928S4 Auto RHD

Tails

Worf928,

Oops, my last paragraph should have read " your assessement of the 7 way connector is correct and I believe that ColinB's set up for the GT (RHD) would have 2 of the seven outlets blanked off".

Also I noted all of my plastic tubes connected to the 7 way connector are black.

Tails 1990 928 S4 Auto RHD

worf928

Thanks tails.
I think it likely that the source of the vacuum is the port under the throttle body. The intake article on the OC site shows a picture of this port.
Whoa. This sounds startlingly similar - if not exactly like - Colin's 'mystery' vacuum line does it not?

ColinB

Dave, Tails.
Been travelling. Now back at home and I've taken some pics to illustrate what I have here. Be patient please, - my earlier attempts to post pics to the board have had limited success. (Aside: thanks Heinrich for enlightening me on this.) If I get it right the first pic will be the 7-way connector. The vac source line from the upper surface of the TB enters from the right between the damper and MAF screen. The outlets are:

Upper left - blanked at connector (presumably for A/T cars)
Upper centre - To fuel regulator (between the rails ahead of the intake manifold)
Upper right - To left rail damper (you can see it clearly)
Lower left - To air pump piping valve (at the moment this is wrongly connected to the 4-way fitting)
Lower centre - To tank vent valve
Lower right - To right rail damper

http://forums.rennlist.com/upload/vac10026.jpg

Second pic shows the 4-way fitting with the blue/black check valve and the (incorrect) vac pipe from the 7-way lower left. The brake booster is out of shot to the left. The two invisible legs of the connector feed the vac reservoir (by a long off-white pipe to the left fender) and to the HVAC.

http://forums.rennlist.com/upload/vac20027.jpg

The third pic shows (drum roll/cymbals) the mystery vac pipe which emerges from the underside of the TB near the MAF. As you can clearly see it goes nowhere and is blanked off. I've racked my brain over this and can only assume that it's there to attach some type of diagnostic tester. It may be different from US cars because this car has no cats or oxygen sensor etc. The bent white vac line on the left is the one from the HVAC control unit to the heater valve.

http://forums.rennlist.com/upload/vac30028.jpg

Looking again through the pics I took when the intake was off (which unfortunately I can't post due to acute computer ineptitude) the original and now missing grey vac pipe can clearly be seen running along the right fuel rail to the flappy solenoid. Also it appears that the 7-way fitting is supplied from the rear upper vacuum source on the TB and my flappy solenoid is now probably being fed incorrectly from the forward upper one. Big Q? now is where should this go.

Dave. Checking your OC page again now. Will post again later.

Colin 89GT "Oh, I'll get by with a little help from my friends"

ColinB

Dave
Still unable to open your OC web page. Excell says the page cannot be found. Have notified them.

Colin

Tails

Colin,
I have reviewed your last 2 posts and make the following comments:

Seven Way Connector
1. My seven way connector for the automatic is basically the same as yours and the blanked inlet would be for the automatic gear box for the auto transmission modulating valve.

2. However, I have another separate blank inserted into my 7 way connector as the black line for the fuel tank vent valve is connected under neath the inlet pipe just forward of the butterfly throttle valve. This should not make any difference as you first image shows that the 7 way connector is connected to the top of the inlet piping just forward of the butterfly throttle valve, so you will be receiving the same vacuum, whether it is from the top of the bottom of the inlet tube, so leave it in situ.

There could be one problem here, is the connection to the inlet piping blanked off, as you show that the line to the fuel tank vent valve comes from the 7 way connector and not from under the inlet piping.

3. All your other connections appear to be correct, except for the line to the air pump piping valve. This should be removed from your four way connector and plugged into the 7 way connector after removing the line for the resonance valve. The resonance (flappy) valve grey plastic tubing runs along the RH side fuel rail to the solenoid valve, which you remove from your 7 way connector should now be plugged into the 4 way connector.

Four Way Connector

1. As yours is shown, except for the change over of the air pump piping valve plastic tube and the resonance valve plastic tube.

2. The white line which has a plug one the end as shown in your last image and is located just above the cam tower cover for the RH side cylinder bank is the same connection as I have on my car and I can only assume that it is connected to the underside of the inlet piping. I cannot confirm this as I'm not able to see under the inlet piping to verify.

If this is correct then there are possibly two connections under the inlet pipe? One for this connection and possibly the other for the fuel tank vent valve (if your 89 is the same as my 90 car).

I believe this blanked off white plastic tube with the orange/red cap is a test port to measure the inlet vacuum at idle or at higher RPM by the use of a vacuum gauge, however, I am not able to verify this.

To verify that you have an air tight induction system, Porsche recomment that an aluminium disk is manufactured as per the diagram shown in the Test Plan EZK-Ignition and LH-Jetronic for 1987 928 S4s on page 2-34. This disk if fitted with a tyre valve connection and a provision for a pressure gauge and is place over the MAF inlet and held in place by 2 by 4mm bolts and nuts with a rubber seal. The test pressure is recommended to a maximum of 0.3 bar and check for leak down. This is too complicated, so if you can get a motorbike tube of around the outside diameter as the top of the MAF, cut the tube through near the valve stem and cut it again the other side of the valve stem sufficient to be able to fold it over and then seal it you can then place the other end over the MAF and by using a jublee clip seal it to the MAF. Pump the tube until it started to inflate over it original diameter and listen for leaks. If it holds at the initial inflation diameter then you have no leaks and all is good. I have used this method to test radiators using a bicycle tube.

Hope this helps.

Tails 1990 928S4 Auto RHD

ColinB

Tails
Thanks for that. I concur with your observations 1,2&3 and that the blanked white line is probably for a vacuum test gauge. My air pump is disabled so I'm not concerned about the vacuum to the air valve. I went to the shop which did the manifold job today. (They also replaced the main TB to intake gaskets so they did the air-tightness test you recommend) After their initial denial, whereupon I produced the pictures taken in their workshop with my missing flappy vac pipe still in place along the right fuel rail, they agreed they had made a mistake. I'm not too worried, they did a good job otherwise but they no longer have the missing vac pipe and you can't imagine how difficult it is to find that type of pipe here. I'll probably have to go to a breaker's yard.

Thanks again. BTW, you're a bit mysterious. RHD, so where are you, UK, Oz??

Colin 89GT

Tails

Colin,
We drive on the RHS and I have lived in two other countries that also drive on the RHS that also liked playing rugby as much as SA. As a matter of fact in one country I played 7 a side rugby for the trophy called "JocKs Pot" and at the start of the Rugby World Cup in 2003 I was in SA in JB.
Tails 1990 928S4 Auto

worf928

There was a stray character in the URL. I have corrected the original post and tested the below link to my intake article from the OC website,

wjm.schepers

Does someone know the part number of the solenoid valve actuator mentioned at bullet nr. 2? As far as I know it is shown in the PET, illustration 107-10, but no part numbers are mentioned.

Rob Edwards

They put it on 103-15, because of course it belongs with the timing belt covers. 911 618 123 01, Pierburg 7.21339.13

wjm.schepers

Yes, that's the one! Thanks.