BrianG

Anyone here able to lay out a step-by-step on the vacuum connections for the brake booster and associated accessories?

pmotts

BrianG

Ummmmm thanks, but that's not quite what I was asking for.................

Unfortunately, that's pretty much everything EXCEPT the Brake booster side of things. I have the large brake-booster line and a similar sized tap in the rear plenum......... but I also have the by-pass valve, the HVAC, the CruiseControl, and one more "under the left fender along with the Cruise Control line" vacuum lines not represented on the above picture....

Also, the Evaporative Control valve on the right side is not attached to anything..... It has it's vacuum supply but not a manifold connection....???

No smog-pump on this car.






But while we have that one up....... which of the throttle-body vacuum outlets do I use? There are 2 on the bottom and another two on the top........

mspiegle

Lets see... I think the brake boosted gets vacuum from the little fitting near the bypass valve.

Also, regarding the TB, I use a fitting on bottom. All you really need to do is ensure that you're using a fitting that sees vacuum when the plate is closed. IIRC, some of the fittings are before the throttle plate and would stop seeing vacuum when the throttle is closed.

BrianG

Ok.... good start......

now....... about the little line with the check-valve...............

and the supercharger by-pass valve..........

and the Hvac and Cruise Control................

mspiegle

Do you have a BEGI? I believe the check-valve goes on the end of that to bleed off pressure

supercharge bypass sees manifold pressures (should hook straight to manifold)

EVerything else should be able to hook into the vacuum "spider"

BrianG

Thanks Mike!

I am not using the BEGI, and so don't need the check-valve in the kit...

I was refering to the check-valve that is attached, by a small line, to the brake-booster.

BrianG

How about we approach this vacuum question in a completely different way.

Is there any reason that ALL of the vacuum-operated systems could not receive vacuum from the same one source? Obviously the brake booster has an apparent flow-rate issue and will be fed by the large (3/8) line off the rear plenum. I wonder, though, if I can use the single, barbed brass fitting to feed all of the other systems??

This would certainly help sanitize the engine compartment since the S4 has nothing besides the Evap Control servo on the right side of the engine compartment.

The single manifold vacuum source would then be responsible for the fuel dampers, fuel pressure regulator, HVAC, CruiseControl, transmission modulator, and Supercharger Bypass.

Is a check-valve necessary in this system?
Is a check-valve necessary in the Brake Booster line?

Comments?

Giovanni

The 85 PS hose cleared the pulley perfectly. I also got a 57mm pulley from DR and the car pulling 8 lbs :-). The pulley he sells is almost similar as our quick change pulley. To be identical you will need to mill 4-5 mm where it sits on the SC. With the 57mm pulley the car will push the p/s hose very quick off the pulley. I tried to position the belt close to alternator belt and also tried to position it close to the SC belt, it still moves it forward almost off the pulley.

Next would be to find machine shop that can make the plate to keep the belt in place.

Giovanni

Pulley, old hose and new hose

BrianG

What's with the lack of responses on the vacuum issue? You guys have to have addressed this on your cars..................

I need to know what sees boost (uses the brass manifold port).
OEM Fuel Pressure Reg ?
Fuel Dampers?
SuperCharger By-pass valve?

Rick Carter

Brian we've already PM'd, this is for the record if anyone esle is foolish enough to DIY

The factory has one way valves in the vacuum hoses going to brake booster and HVAC. Rob replaced all the OEM hoses with a larger (I don't know the size) hose to the brake booster with a one way valve in it and also one in the HVAC hose.

BrianG

We did PM, Rick, but you didn't tell me about the FPR and the By-Pass valve.....

I'd like some rationale for the answers, too, so that I can get a better understanding of the whole vacuum system, in the bosted envrionment.

Rick Carter

Everything but the brake booster and HVAC "sees" boost and vacuum, including the FPR, By-pass valve and dampners.
Rick

BrianG

I don't understand why the CruiseControl, Evaporative Control System valve, Transmission Modulator Valve, and Fuel Dampers would want to see boost.

In fact, I wonder if it would actually be unhealthy for those actuators to see boost, since they were not seeing boost in the OEM application and may not be designed for positive pressure...........