Re: Boost problems, redux.

[Thomas Tornblom <Thomas.Tornblom@nexus.comm.se>]

> Date: Thu, 1 Sep 94 17:39:20 EDT
> From: glen@mass.smc.com (Glen Powell)
> Cc: listquattro@swiss.ans.net, quattro@di.com
> Reply-To: quattro@swiss.ans.net
> X-Charset: LATIN1
> X-Char-Esc: 29
> 
> 
> Interesting, now we are getting somewhere! How does the  CPU-controlled
> valve increase the boost? Is pressure supplied to the WG cap to add to
> the tension applied to the spring to hold the WG closed at higher boost
> levels? I would have guessed that the CPU would have applied vacuum to
> the WG cap to reduce the effective force of the spring to reduce boost
> when/if knock is detected, pure speculation on my part here. I'll scope
> the wires on the valve and see if the CPU sends any signal at FWO (WOT)
> as my next step and report back.....

Yes, manifold pressure is applied on top of the WG to aid the spring.

Valve open -> manifold pressure on top of WG
Valve closed -> normal air pressure on top of WG

I guess this is to make it more fool proof. If there is some
malfunction in the system, you wont be able to get more boost than
what the spring gives you.

Thomas