[s-cars] Chasing a boost leak -

Mon Apr 16 04:01:54 EDT 2007

i'm not sure i'd agree with that.  to produce boost, the ECU increases
the WGFV duty cycle.  the WGFV could be working fine at low duty cycles
and failing at higher duty cycles.  that's what happened to my car.
the maximum boost started dropping and eventually, i was frequently getting
only WG spring pressure.

disconnecting the WGFV (i assume you mean unplugging the electrical 
connector) won't give you any reliable information, IMHO.

-teddy

--- Ingo Rautenberg <ingo.rautenberg at gmail.com> wrote:

> My guess is the WGV is probably OK.  Easy test is disconnecting it  
> and see.  If it's functioning properly, you should find noticeably  
> less boost (like 12-13 lbs IIRC).
> 
> What about Leaking BPV?
> 
> Ingo
> 
> On Apr 15, 2007, at 11:09 AM, Mike Claire wrote:
> 
> > re: the WGFV - I ran the Motronic diags described on Scott  
> > Mockrey's site, which includes the WGFV.  I'm talking about the  
> > test that checks the throttle pot, the injectors, the carbon  
> > canister valve, ISV, etc.  The WGFV clicks the same as it always  
> > has.  Is that good enough to eliminate it as a suspect?
> >
> > I have Samcos with breeze clamps.  The entire intake system  
> > including PVC system pretty much holds 10 or 15 lbs pressure (using  
> > a 3 inch PVC pipe cleanout with a compressor quick connect tapped  
> > into it.  It doesn't hold pressure indefinately, it does leak down  
> > very slowly.   Mostly through the valve cover oil cap.  I had to  
> > push down pretty hard on it to build pressure.
> >
> > Bob Myers reminded me to check the ECU connection in the cabin -  
> > good call because somehow I overlooked it.
> >
> >
> >
> > Thanks again guys, I'm out of ideas of my own.
> > Mike
> >
> > On 4/15/07, Ingo Rautenberg <ingo.rautenberg at gmail.com> wrote:
> > Faulty WGFV?  Have you actually removed and examined all of the hoses
> > for possible tears?  Improperly-torqued-down hose clamps - rips at
> > the hose clamps (if oem hoses).  That lower hose at the passenger
> > side at the turbo seems to be the culprit more often than not IME.
> > One that really threw me off at the track at Road America in 2001:
> > boost leak at the aftermarket VDO boost gauge!
> >
> > Hope you find it sooner rather than later!
> >
> > Ingo
> >
> > On Apr 15, 2007, at 2:26 AM, s-car-list-request at audifans.com wrote:
> >
> > > From: "Mike Claire" <mike.claire at gmail.com>
> > > Date: April 15, 2007 2:26:42 AM GMT-04:00
> > > To: "S-car list" < s-car-list at audifans.com>
> > > Subject: [s-cars] Chasing a boost leak -
> > >
> > >
> > > Gents:  After spending some time in the Home Depot plumbing
> > > department, I
> > > figured I'd make short work out of my boost woes.  But, no joy.
> > >
> > > The subject is a '93 with a metal crossover, all-metal intercooler,
> > > Samcos,
> > > and Pastore 1+ chip.  I'm used to seeing 22 lbs on full boost  
> > with my
> > > Autometer boost gauge.  Now it reads more like 16 or 17 lbs, and
> > > there are
> > > some new boost-related noises coming from under the hood.
> > >
> > > Here's my main question:  If I'm missing 5 or 6 lbs of boost, is
> > > that a big
> > > enough leak to easily find when I pressurize the plenum with about
> > > 10 or 15
> > > lbs with my compressor?  Because I'm not hearing it.  I figured a 5
> > > lb leak
> > > would be easy to hear.
> > >
> > > Now I'm wondering if it's even a leak at all, or if it's the ECU
> > > backing off
> > > boost.  I pulled the codes by blinking them out.  Results are
> > > inconsistent.
> > > I've seen 2212 (throttle potentiometer), and 2111 (RPM sensor),
> > > intermittently.  I've had no symptoms of problems with these.  I  
> > read
> > > everything on Scott Mockrey's site, and ran the Motronic
> > > diagnostics (which
> > > includes the throttle pot), no problems.
> > >
> > > I've been chasing this issue for weeks now, and sometimes I see  
> > codes,
> > > sometimes I get no codes at all.  I'm not convinced the spurious
> > > codes are
> > > even related to the low boost problem - for all I know the car's  
> > been
> > > throwing codes a long time.  The car's running well, but not  
> > perfect.
> > > Occasionally I get slight misfiring under full boost.  I've been
> > > suspecting
> > > a weak coil - but who knows.    16 lbs boost is way higher than
> > > limp home
> > > mode, so I don't know - can the ECU even be involved here?
> > >
> > > One more thing about the codes - I haven't seen any since I
> > > replaced the
> > > little rubber tee hose that connects the PCV to the underside of
> > > the intake
> > > - it was split wide open.  (I only picked up a pound or 2 of boost
> > > after
> > > fixing it.  But the boost needle doesn't flutter anymore).
> > >
> > > In general, the car pulls strong and smooth, but boost is low.
> > >
> > > So - boost leak, ECU backing off boost?  Or 3rd option - is a
> > > failing turbo
> > > a possibility?  There's a weird noise under there between 8 and 10
> > > or 11 lbs
> > > when under WOT.  I can't even describe it, but I pictured a split  
> > hose
> > > making that noise.  There are no split hoses.  But the noise is
> > > fairly new,
> > > and it's only heard at WOT, when boost is building fast.  I hear
> > > the turbo
> > > whistle just like always.
> > >
> > >
> > >
> > > Thanks
> > > Mike
> >
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> >
> 
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