[s-cars] Chasing a boost leak -

[Ingo Rautenberg]

Teddy,

As I recall (may be a bit fuzzy) with my 200q20v and Hoppen chip,  
this is exactly what I did before deciding to replace the WGFV.   
Unplugging the WGFV definitely reduced boost levels.  Of course, I  
don't think I had the WG spring cranked down too far at the time,  
either ;-)

Ingo

On Apr 16, 2007, at 4:01 AM, Theodore Chen wrote:

> 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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