The Project is coming along

[tomc at satx.rr.com (tomc)]

Thanks Mark,

Further investigation found a big vacuum leak behind the intake manifold
at the bypass. After fixing it I can now adjust idle to 900rpm. she
stills purrs, but with a slight miss (she needs a tune-up anyway).

Thanks for all your help and keeping me inline,

Tom C.
'79 "The Project" Scirocco


On Tue, 2003-09-02 at 15:09, Mark wrote:
> > -----Original Message-----
> > From: tomc [mailto:tomc@satx.rr.com]
> > Sent: Tuesday, September 02, 2003 9:48 AM
> > To: Mark
> > Cc: Scirocco list; Texas Scirocco Team
> > Subject: RE: The Project is coming along
> >
> >
> > Ok, I don't think that's my problem then. I have a consistent 1300rpm
> > whether warm or cold,
> 
> 
> If the idle bypass is stuck, the idle will start out high (normal) AND
> remain high after the car is warmed up.  I would try disconnecting it and
> plugging the hoses before screwing with your fuel/air mixture...
> 
> 
> > I also don't have the fluctuation indicative of a
> > vacuum leak.
> 
> 
> What do you mean by fluctuation?  If you have unmetered air entering at some
> point after the airbox this will raise your idle.  As long as the vacuum
> leak is consistent, you idle speed will be smooth - just higher.
> 
> 
> > I'm pretty sure if I set my timing with no advance it will
> > idle at 900, I'll try it later to be sure. I may just need to play
> > around with the fuel/air mixture.
> 
> 
> That would be the last thing I would screw around with.  Vacuum leaks can be
> tricky to track down.  Are there any cracks in your rubber boots?  Clamps
> all tight?  Injector seals in good shape and seated all the way in?  Small
> vacuum lines free of cracks (the "cloth" material covering the ends
> sometimes hides cracks in the rubber underneath)?  Only after you're
> absolutely sure you don't have any type of vacuum leak (including a faulty
> idle bypass) would I suspect that the fuel/air mixture is too rich...
> 
> Maybe try asking your question again under a separate subject heading -
> someone else might chime in that wasn't following this thread...
> 
> HTH!
> 
> Mark.
> 80 S
> 81 S ABA/JH/4K
> 
> 
> > On Tue, 2003-09-02 at 14:16, Mark wrote:
> > > > -----Original Message-----
> > > > From: tomc [mailto:tomc@satx.rr.com]
> > > > Sent: Tuesday, September 02, 2003 6:44 AM
> > > > To: Mark
> > > > Cc: Scirocco list; Texas Scirocco Team
> > > > Subject: RE: The Project is coming along
> > > >
> > > >
> > > > Thanks all for the help, I thought that dohickey thing was
> > for the lamba
> > > > system (no really I did!). Anyway, I'll just put my fuel dizzy on the
> > > > airbox for now. I'll want a lamba system down the road
> > sometime though.
> > > >
> > > > As for my other problem, I checked my vacuum lines (what's
> > left of them)
> > > > I don't see any leaks, however I have a good vacuum at the front of my
> > > > intake manifold and nothing at the rear. Removing the line that goes
> > > > from the back to the vacuum advance on the dizzy does nothing to the
> > > > idle or timing for that matter, I was under the impression that it
> > > > should though. Is this a stuck idle bypass? and if so how do
> > I un-stuck
> > > > it?
> > >
> > > In my experience once the bypass is "stuck" it's no good
> > anymore.  To test
> > > if this is your problem, remove it and plug both hoses (PP
> > bolts work good
> > > for this IIRC).  If the idle goes down now, that's your problem
> > (or at least
> > > part of it :-)
> > >
> > > If you want to check the operation of the bypass valve, apply
> > 12 volts to
> > > it, wait for bit, and see if you can blow through it.  If you can,
> > > bypass-a-no-good...
> > >
> > > Mark.
> > > 80 S
> > > 81 S ABA/JH/4K
> > >
> > >
> >
>