Vacuum Diagrams

  • ahspros
  • ahspros's Avatar Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
07 Aug 2013 14:30 #15547 by ahspros
Vacuum Diagrams was created by ahspros
Where can I find a vacuum diagram for my 86.5 928?
I have a leak some where as my cruise control will not work properly. It tries to work but seams that it does not have enough vacuum. Did a vacuum check on the modulator and it works just fine. Removed the inter fender housing looking for a loose line, not there. When I push to set the speed I get a small bump in speed but will not hold. Put in a different controller with no change.

Walt:confused:

Please Log in or Create an account to join the conversation.

More
08 Aug 2013 10:27 #15552 by emmanuelli
Replied by emmanuelli on topic Vacuum Diagrams
s287999742.e-shop.info/online/templateme...LINE+DIAGRAMS+S3.pdf

click that link. it contains the original vaccum line diagram with the 928 motorsports simplification overlay on it. my mechanic used when i did an intake refresh on mine.

Hope it helps

Please Log in or Create an account to join the conversation.

More
09 Aug 2013 10:50 #15558 by wallyp
Replied by wallyp on topic Vacuum Diagrams
Go to the vacuum brake booster. Find the small black/blue check valve, and the four-way vacuum connector. Find the line that disappears into the firewall - this line feeds the HVAC system. Disconnect this line and plug the opening on the connector. Try the cruise control - if it now works well, the problem is a vacuum leak in the HVAC system, usually a split diaphragm in an actuator.

You can test the actuators, and temporarily plug the line going to the leaking actuator to make the cruise control and the HVAC system work better.

Wally Plumley
928 Specialists
www.928gt.com

Please Log in or Create an account to join the conversation.

More
11 Aug 2013 21:31 #15587 by mm928
Replied by mm928 on topic Vacuum Diagrams
I have gotten everything to work except my cruise with regards to vacuum and we have refreshed all vacuum lines and connector I believe in the engine bay. So thanks Wally for that simple test so identify the HVAC cabin-side leak! I will check it out.

Walt - do not be disheartened though if your Cruise is hard to get going,,,almost all of our cars leak vacuum! But it also could be a something in the cruise control brain, I understand they sometimes just flake out. So if Wally's test does not help you might also look there. You can pick up a used module sometimes fairly cheap to test it out.

1983 928S - 16v 4.7L L-Jetronic
Dark Grey w/ Blue Leather
85/86 exhaust manifolds
Y-Pipe
SS Hi-perf Cat
S4 springs
Bilstein shocks
Air pump delete
VIN: WP0JB0926DS861180
- - Isn't Life great? - -

Please Log in or Create an account to join the conversation.

  • ahspros
  • ahspros's Avatar Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
17 Aug 2013 15:55 #15661 by ahspros
Replied by ahspros on topic Vacuum Diagrams
Found a bad leak in HVAC, new part on order. Tried the part of closing off the vacuum to the AC. Now have around 17wc on lines going to the actuator and vacuum canister. Now when I push the lever the speed will increase, but when I let go of the lever speed will not hold. Tried a second controller with now luck. Now think it is in the actuator. Have a used unit coming.

Walt

1986.5 928s

Please Log in or Create an account to join the conversation.

More
17 Aug 2013 17:01 #15662 by mm928
Replied by mm928 on topic Vacuum Diagrams
Mine does soemthing similar, I think I should have enough vacuum, but it will engage and go to about 72 every time...no matter what I try to set it to. So I think have somethings else going on as well. I have a spare newer module though I will try when I find some time. Keep us posted....

1983 928S - 16v 4.7L L-Jetronic
Dark Grey w/ Blue Leather
85/86 exhaust manifolds
Y-Pipe
SS Hi-perf Cat
S4 springs
Bilstein shocks
Air pump delete
VIN: WP0JB0926DS861180
- - Isn't Life great? - -

Please Log in or Create an account to join the conversation.

More
21 Aug 2013 20:18 #15684 by ROG100
Replied by ROG100 on topic Vacuum Diagrams
Vacuum diaphragms are available for the center and footwell actuators.

Please Log in or Create an account to join the conversation.

Moderators: Rich928mm928billvvOC

Don't have an account yet? Register Now!