Pelican Parts
Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   Pelican Parts Forums > Porsche Forums > 911 / 930 Turbo & Super Charging Forum


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Registered User
 
Join Date: Jul 2006
Location: S. Florida
Posts: 7,274
The vacuum solenoid has nothing to do with boost retard.
Nobodies gonna loose any sleep if you wanna think so though.

The vacuum solenoid is kind of like a single pole double throw switch. It has 3 vacuum hose connections so it can be hooked up and used two opposite ways when voltage is applied while the 3rd remaining connection is vented to air.

In the origonal configuration it blocks air from flowing through the 2 vacuum hoses connected to it when voltage is applied so there is no vac retard on cold starts and the timing advances and the idle raises.

After a couple minutes the voltage is taken away and the spring loaded internal solenoid valve relaxes and opens and lets intake manifold vacuum through to the inner distributor pot and retard the timing at idle and during deceleration, in the origonal configuration.

Now the one in my car has a much more useful purpose.
I use it with the hoses hooked up differently so it blocks air when no voltage is applied and passes air between the 2 hoses connected to it when voltage is applied and I'm using it as a "boost clamp" on the WUR with an adjustable rpm switch.
The remaining hose connection is vented to air with a downward curved hose to keep rain water from getting in.
Old 04-06-2010, 03:57 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #121 (permalink)
Rocket Scientist
 
Join Date: Jun 2008
Location: Detroit
Posts: 896
I tested the following:

10 psi air to both sides - no change of the actuator rod length
10 psi air to back side only - no change of the actuator rod length
10 psi air to the front side only - rod extended (retarded) 4mm

20 In Hg vacuum to both sides - no change of the actuator rod length
20 In Hg vacuum to back side only - 4mm extension (retarded)
20 In Hg vacuum to front side only - 2mm retraction (advance)



I dug out the solenoids and tested them:

No Power - Distributor port is connected to source port. I checked with both 20 In Hg vacuum and 15 psi air.

12V applied to solenoid - Source port is shut off and distributor port connects to atmosphere. I checked with both 20 In Hg vacuum and 15 psi air.



I did all this work. Is it asking too much for somebody with a stock car to run a couple of wires back to the solenoid with the car under boost and check for voltage?
Old 04-06-2010, 07:10 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #122 (permalink)
sudo apt-get purge 930
 
equality72521's Avatar
 
Join Date: Jul 2006
Location: Brandon, FL
Posts: 4,840
If I had solenoids I would.
__________________
Mark 1979 930 Euro ***GONE AND DON'T MISS IT AT ALL***

"Worrying about depreciation on your car and keeping mileage down is like not ****ing your girlfriend so her next boyfriend finds her more appealing"
--clutch-monkey
Old 04-06-2010, 07:13 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #123 (permalink)
Registered User
 
mark houghton's Avatar
 
Join Date: Jul 2008
Location: Central Washington State
Posts: 3,775
I love emperical data! Keep it up guys, the mystery shall be unravelled.
__________________
Mark H. 1987 930, GP White, Wevo shifter, Borla exhaust, stock everything else. The result of a massive Pelicanite good will fire recovery effort. Truely an open book, ready for the slippery slopes to modification.
Old 04-06-2010, 07:27 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #124 (permalink)
Registered User
 
Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
Speedy Squirrel,

Great work.

So we have confirmation the dist can not advance with pressure to each side.

So how do we get retard?

The 2mm w vac to the boost side is probably nothing as the is going to see positive pressure at cruse.

If the solenoid dose block, it might be from changes at the TPS or RPM as you have noted.

I do not know if any system that monitors boost level in the electronics.

New thought, I do not see how but is there a way to configure the ported vac/boost connections at the TB so the dist would only see boost at advanced throttle angle?

Is the pot in good order, no leaks?
Old 04-06-2010, 08:06 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #125 (permalink)
Registered User
 
Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
Quote:
Originally Posted by Speedy Squirrel View Post
I tested the following:

10 psi air to both sides - no change of the actuator rod length
10 psi air to back side only - no change of the actuator rod length
10 psi air to the front side only - rod extended (retarded) 4mm

20 In Hg vacuum to both sides - no change of the actuator rod length
20 In Hg vacuum to back side only - 4mm extension (retarded)
20 In Hg vacuum to front side only - 2mm retraction (advance) ...

I dug out the solenoids and tested them:

No Power - Distributor port is connected to source port. I checked with both 20 In Hg vacuum and 15 psi air.

12V applied to solenoid - Source port is shut off and distributor port connects to atmosphere. I checked with both 20 In Hg vacuum and 15 psi air.
If pressure (boost) to both sides of the pressure box dose not effect timing, how are we getting retard?
Old 04-08-2010, 08:42 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #126 (permalink)
 
Registered User
 
Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
I might see an opportunity from SS's info if we can get it to advance with vacuum. If we get 9 deg with 4mm, just ruining with the outer pot connection might get us 10 deg boost retard and 4-5 deg vac advance.

Must be attached to a ported connection at the throttle body that sees vac at curse but not at idle.

Staying with stock timing for now, that would let us run close to 11 at idle (disconnected so no vac retard ), -17 on boost (apx 9 deg of retard) , and about 29 on cruse (+4 deg of vac advance).

We could advance this to about -15 at idle, -21 on boost and -34 at cruse.

Just a thought.
Old 04-08-2010, 08:50 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #127 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 12:55 PM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.