[urq] Warm-up regulator questions

[urq]

First off, congratulations on the addition to the family!

I don't remember if it was the Fox or the urq, but yes, I have taken a
Control Pressure Regulator apart and reassembled it successfully.  They
aren't really that complicated inside ... I'd recommend holding off on
buying a replacement until you know for a fact that yours is unrepairable.
What might make it unrepairable?  Once thing that comes to mind is the
heating element on the bimetallic strip burning out.  It sounds as though
you have verified this not to be the case.  

Before taking anything apart though, get a fuel pressure gauge and verify
the control/system pressures are within the proper range based on
temperature.  IMO the fact that you have tried two different ones and get
similar results does tend to indicate that the CPR is working ... 

Based on your description I would wonder if the Auxiliary Air Valve is stuck
closed.  Another possible culprit is the temp sensor on the head I suppose,
but that would be a long shot.  

There's no question, the vacuum plumbing to the CPR on the WX is a bit odd
... it looks like there's a simple "Y" that connects the chambers on either
side of the diaphragm, but when I took mine apart I found that there's a bit
of a restriction in the suction line to one side.  The only thing I can
think that such a  restriction would be for is some sort of dynamic
enrichment, like an accelerator pump on a carb.  I'm pretty sure that vacuum
switch is closed when the engine is cold.  

Good luck!

Steve B
San José, CA (USA)


-----Original Message-----

My freshly rebuilt stock WX is experiencing a rough idle during the warm-up
phase. It starts very easily, hot or cold, but during the first 30 seconds
when cold I must help it survive with the gas pedal. My understanding is the
WUR is bad or dirty. I've swapped it for another one I have, same result.
Both WUR electrical parts are OK, showing continuity when tested. When hot,
the engine is fine with a nice air-fuel ratio on the rich side. The urQ WUR
part number is 0 438 140 094 or 035 133 403D.

 

Before I open one of them, I have a few preliminary questions :

1-       There are two vacuum ports on them, and both ports are connected
together via tubing and a T-piece and the other part of this T is connected
to the thermo-vacuum switch. Is this right ?

2-       Is the thermo-vacuum switch supposed to be closed or opened when
cold ?

3-       Is there a good way and a wrong way of connecting that switch ? Or
is it only a valve allowing some vacuum/boost to reach the WUR when cold/hot
?

4-       Anyone had opened a WUR before for cleaning purposes ?

 

A new WUR is a 500$+ affair, so I've looked other solutions if I must
replace it. Look at these guys, they propose a variable pressure WUR which
one tunes via a laptop. It looks very interesting, but price for a turbo
engine WUR is 600$.Ouch! 

http://unwiredtools.com/

Look for the UTCIS-PT, that's the one for turbo engines.

Brady, could this be a nice thing for tuning a CIS lightly modded engine ?