Cruise Control vacuum line issue on 1980SC Targa

[targa80]

I have started working on the cars ancillary systems that have stopped working over the years and naturally create a challenge to get them working again.

1. Seat Belt light and Key in ignition buzzer
2. windshield washer pump and reservoir
3. Windshield washer delay
4. Cruise Control

The first three are now working.

1. Seat Belt/Key Buzzer - Cleaned all circuit connector contacts, re flowed solder on relay circuit board contacts adjusted relay variable resistor for time delay. (I know why use this annoying function in the car, Answer because I can)
2. Windshield washer pump and reservoir - Freed stuck washer pump motor, cleared clog on one way pickup valve in the reservoir.
3. Windshield wiper Delay - Broken terminal connector on Delay switch.

I have done the prerequisite search on the cruise control system for the SC model years looking for information. Gathered a wealth of knowledge but still have a nagging question on the vacuum line routing for the tempostat servo motor.

First some history, cruise control worked with a very slow drop in speed over time while driving. (research shows that this may be an issue with capacitor C19 deteriorating with age). In the late 90's I did an engine rebuild and after installing the motor the cruise no longer worked (Fast forward to now, (I Know, what took so long, Poop happens, but now I'm retired with free time on my hands).

After doing all of the multi-meter tests I found the clutch switch needed adjusting. The cruise will engage with switch Set activation and car will accelerate but will not hold speed once Set switch is released. Before I start troubleshooting the tempostat control unit, I need to verify the vacuum connections between item 15 tempostat Servo Motor and the tee connector between item 13 Deceleration valve and item 1 throttle housing as noted in the Vacuum Line Layout for the 1980 911SC model below.



The Porsche repair manual diagram shows item 15 Vacuum Limiter (Deceleration Valve) connected directly to item 4 Flap Nozzle (Throttle housing)



This is a picture of my motor after my rebuild and it clearly shows that the vacuum line on the Deceleration Valve is connected directly to the Auxiliary Air Valve.



I did connect the Tempostat Servo Motor vacuum line directly to the open vacuum connector on the throttle housing after the engine was installed. The open connector is in the middle of the picture next to the frequency valve.



Can anyone provide a picture of the engine vacuum line setup between the two valves for a 1980 model or provide info on how theirs is setup. The only thing I can think of with my setup was that I got it wrong when I put all the ancillaries back on the engine. As a side note the engine CIS system runs as advertised with no issues. If I am right in my setup then the pubs are not accurate. Your thoughts and insight would be appreciated.

[smarens]

I have a 1980 SC Targa, just dropped my engine, I don't know what the two valves are, I have a lot of pictures of the engine out of the car, can you give me better detail and I can get you some pictures of that area

-also can you post some pictures of your car, mine is Mocha Brown also but was repainted, I'm changing it back to Mocha Brown

[targa80]

The first picture in my post shows the two little flying saucers (Brass Discs with hoses attached. I believe the lower one is the Deceleration Air Valve and the top one is the Auxiliary Air Valve. There is a small vacuum line connecting the two together on the oposite sides of the larger hose connections.

[targa80]

The two air valves are indicated by the arrows I believe the upper is Auxiliary Air Valve and the bottom one is Deceleration Air Valve. As you can see the two small vacuum lines are connected together is this correct for an 1980SC 3.0L engine with cruise control?

[targa80]

I'm Starting to think that someone prior to me owning the car replaced the the Auxiliary air valve with a Deceleration valve. Any search I have done shows the Auxiliary Air Valve without the small vacuum nipple.

[uwanna]

Originally Posted by targa80

After doing all of the multi-meter tests I found the clutch switch needed adjusting. The cruise will engage with switch Set activation and car will accelerate but will not hold speed once Set switch is released. Before I start troubleshooting the tempostat control unit, I need to verify the vacuum connections between item 15 tempostat Servo Motor and the tee connector between item 13 Deceleration valve and item 1 throttle housing as noted in the Vacuum Line Layout for the 1980 911SC model below.

Given that the cruise will activate with the set switch but not hold speed is assurance that the vacuum to the servo motor is working correctly however the electronic control module is not.
You are having a problem with the electronic control module. I have worked on many cruise modules and that is a very common fault. My advise is to send your module to the guy mentioned in this thread.
Don't bother with trying to replace capacitors or other components
and stuff. Several folks have had great results from this guy and at his price, it's not worth messing with the module yourself.

New Cruise control repair guy on the block

[/QUOTE]

[targa80]

Originally Posted by uwanna

Don't bother with trying to replace capacitors or other components
and stuff. Several folks have had great results from this guy and at his price, it's not worth messing with the module yourself.

New Cruise control repair guy on the block

[/QUOTE]

Uwanna,

Thank you for the advice and at some point I may move in that direction but for now I would like to resolve the issue that I have with how the vacuum lines are connected to the Decel and Aux air valves on 3.0L motor. In my own situation things are just not adding up with the configuration I presently have even though the engine runs great. Once I get the vacuum lines issue straightened out then I will tackle the tempostat control unit. I do not shy away from troubleshooting component failures on electronic modules, in fact I derive a little bit of satisfaction from repairing faulty equipment that I own.

[smarens]

so far from everything I see I think my car is pretty original and not tweaked much, this is a picture I had saved, can get you any picture you need tomorrow, don't forget to post pictures of yours, I want to see Mocha Brown

[smarens]

ok found this one too, you can see where the vacuum line on lower vacuum pot runs to

[smarens]

Originally Posted by targa80

I'm Starting to think that someone prior to me owning the car replaced the the Auxiliary air valve with a Deceleration valve. Any search I have done shows the Auxiliary Air Valve without the small vacuum nipple.

my pictures show only one of the pots with a vacuum nipple on it

[targa80]

[QUOTE=smarens;10299593]ok found this one too, you can see where the vacuum line on lower vacuum pot runs to

Looking at your last picture the vacuum line from the decel air valve runs directly to the throttle housing with no tee in between for cruise control. Question is do you have cruise control in your car? If you do where did the vacuum line from tempo stat servo connect to?

[smarens]

Originally Posted by targa80

Looking at your last picture the vacuum line from the decel air valve runs directly to the throttle housing with no tee in between for cruise control. Question is do you have cruise control in your car? If you do where did the vacuum line from tempo stat servo connect to?

my car does have cruise but when I took the engine out 2 weeks ago only the cable from the cruise servo was connected to the throttle, nothing else, servo is still in the engine compartment but I didn't even know it had a vacuum port on it

-do you want pictures of my cruise servo or anything else?

[targa80]

Originally Posted by smarens

my car does have cruise but when I took the engine out 2 weeks ago only the cable from the cruise servo was connected to the throttle, nothing else, servo is still in the engine compartment but I didn't even know it had a vacuum port on it

-do you want pictures of my cruise servo or anything else?

Do you have an open vacuum port on the throttle housing like I have in the second picture from my original post?

[smarens]

Originally Posted by targa80

Do you have an open vacuum port on the throttle housing like I have in the second picture from my original post?

no, my port on the top has red vacuum to the distributor, the lower one on the throttle housing goes back over to the lower vacuum pot with braided vacuum on my previous picture

[targa80]

Finally found another picture of a 80SC with both the Decel and Auxiliary Air Valves having a vacuum line port. In the picture the upper unit (Auxiliary Air Valve) has no connection. The bottom unit (Decel Air Valve) has a vacuum line attached with a tee connector branching off to the throttle housing and the open end would be for the Tempostat Servo Motor.

[pmax]

The engine pics above do not show the CC connection ... it wasn't a standard feature on these cars (I think). That hose from the TB goes to both the DV and CC actuator. Many have the DV plugged so that's another mod to be aware of.

[targa80]

After doing another internet search it seems there is an older version Decel Valve.





There is also a different set up with the newer Decel Air Valve and the normal Auxiliary air valve without the small vacuum line port.



In essence having the two small ports connected together on the Decel and Auxiliary Air valves in my configuration eliminates the Decel valve from operating normally by not supplying a vacuum to it. The throttle body vacuum port was connected directly to the Tempostat Servo Motor so there was no open vacuum port.

Now that I have that figured out its time to look at the Tempostat Control Unit.

[smarens]

keep us posted, I want my cruise (and everything else) on my car some day to all work

[targa80]

Originally Posted by pmax

The engine pics above do not show the CC connection ... it wasn't a standard feature on these cars (I think). That hose from the TB goes to both the DV and CC actuator. Many have the DV plugged so that's another mod to be aware of.

I marked where the tee connector is located and coming from the Decel Air Valve, one end of the tee goes to the throttle housing and the other end of the tee goes to the Cruise Control (CC) Tempostat Servo Motor (not shown)

[gazzerr]

Pat I have an '82 and that's how my lines are connected also.

That top flying saucer is definitely wrong. That looks like another decel valve to me. It should be an AAV that looks like:

this




It gives an extra puff of air on start and closes on vacuum. Check for holes in the metal pipes. The airbox rubber mounts sag and the pipes rub on the engine shroud.