Re: Help ! WGFV - How does it look, FCO, and fault modes for boost-gauge.

[Greg & Britt <image_one@earthlink.net>]

Kenn Thyrsted Nielsen wrote:
> 
> Hi, all.
> 
> Experiencing FCO, maybe caused by overboost, AND having a periodically
> malfunctioning WOT switch, i suspected the WGFV.
> 
> Tracing the vaccum hose from the WG led to --- NOTHING...
> 
> This *could* explain the FCO, - but at warmer temperatures i haven't
> experienced FCO.  But also less performance, wich might be caused by the
> WOT-switch.
> 
> Maybe i reached overboost due to the fact that the air is cold, and
> therefore humidity is lower causing the WOT switch to engage fuel enrichment
> ?
> 
> BUT, I now have two (obvious) problems :
> 
> First:  How does the WGFV look like ?  I thought it was a small cylindric
> valve placed on the firewall, with the word "DUTY SOLENOID" and the number
> 035 906 203 some-letter on it. But both the hoses are connected to some
> other hoses..

Should be mounted next to the ignition coil on a rubber isolator.

> Now, -as i understand the function of the WGFV, it switches between vaccum
> (turbo intake) and pressure (intake manifold), wich gives three hoses. There
> are only two on the darn thing.

The vent line connects to the turbo inlet elbow which is very close to
atmosheric pressure, not vacuum. Correct on the other line that connects
to the intake manifold, AFTER the throttle plate which can be vacuum or
pressure, depending on throttle plate position. This is also where the
BG gets its vacuum-pressure sourced.
 It should indeed have three hoses connected. One hose to the turbo
intake boot, one to the WG and one to a fitting on the back of the
intake manifold. Note this discription is for my 87 MC. My 84 KH is a
slightly different animal.  It does use vacuum from the vac reservoir to
quickly open the WG.

> Seccond: What is the most common failuremode for the boost-gauge. Could it
> be causing FCO ?

The gauge itself is totally independent of FCO, further inside the
controller the signals may use a common source but I don’t have that
info. Might some one in Q-land have that info?

GT

84 5KT
87 5KCST