cutout/stumble on an MC engine

[james accordino]

I think you might be more on target.  First day
everyone said "overboost".  Lower hose is fine, like I
thought, but the wastegate diaphragm that I had never
checked was also fine.  Holds vac. and looks fine
also.  Besides my boost gauge NEVER went over 1.4 bar.
 For a while I had a fault code and IGN fault light on
the dash from the #2 knock sensor.  I removed cleaned
and retighten twice.  I think I finally replaced it
with another knock sensor I had around.  It was off a
much lower mileage car, and just generally looked to
be in much better condition.  BUT, it was not the
correct part by spec.  Although the light and fault
codes no longer appear, I'm beginning to wonder if
these knock sensors have different design parameters,
and this might be fooling/confusing the ECU.  Today
the car pulled much better, but still not quite up to
snuff.(my observations)  Walked away from a new
Infinity QSX?.  85 to 95 I barely left him, but from
95 to 125 he disappeared pretty quickly.

Thanks
Jim Accordino

--- "Doyt W. Echelberger" <Doyt at buckeye-express.com>
wrote:
> If it isn't eager to go from 85 to 110, you do have
> problems. I'm 
> free-associating now.......restricted induction ie.
> air cleaner, throttle 
> valve; restricted exhaust producing back pressure;
> inadequately rich fuel 
> mixture; retarding of timing due to knock or
> ECU-imagined knock.
> 
> Doyt
>  >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>..
> At 06:28 PM 8/8/2001 -0700, you wrote:
> >Big thanks to all who replied.  Everyone had the
> >identical answer.  I'm not sure this is the problem
> as
> >the hose SEEMED fine.  Visual and manual inspection
> >recently.  The dash boost gauge never goes over 1.4
> >bar.  The cutout is very short.  Definitely less
> than
> >1 second.  I have about 3 or 4 wastegates laying
> >around, but have never opened one.  I will check
> the
> >diaphragm on the car and and hose and report.  One
> >other symptom I noticed is that on a long steep
> >incline with throttle wide open and 1.4 bar
> indicated
> >the car takes forever to accelerate from say 85 to
> >110.  It just doesn't seem to have any guts.  Could
> >the weather (95* Fahrenheit and 85% humidity) have
> >anything to do with this?  Is it possible I'm
> running
> >too lean a basic setting?  Maybe time for a cutoff
> and
> >plug check?  Again thanks for the responses and
> I'll
> >let you all know what I find.
> >
> >Jim Accordino
> >--- Peter Berrevoets <pjberr at home.com> wrote:
> > > Ah... the dreaded overboost cut-out; sort of
> like
> > > hitting a brick wall?
> > >
> > > Check that the big hose to the bottom of the
> > > wastegate hasn't crumbled with
> > > age and is leaking, preventing the wastegate
> from
> > > functioning properly.
> > >
> > > If that is fine, you may have a tear in the
> > > wastegate diaphragm, I don't
> > > know if wastegate frequency valve failure will
> allow
> > > for an overboost
> > > condition as well, but maybe someone else might.
> > >
> > > HTH
> > >
> > > Cheers!
> > >
> > > Peter Berrevoets
> > > 1990 200TQ
> > > Toronto, Canada
> > > http://frontpage.home.net/pjberr/
> > >
> > >
> > >
> > > > >-----Original Message-----
> > > > >From: quattro-admin at audifans.com
> > > > >[mailto:quattro-admin at audifans.com]On
> > > > >Behalf Of james accordino
> > > > >Sent: Tuesday, August 07, 2001 11:26 PM
> > > > >To: audi list
> > > > >Subject: cutout/stumble on an MC engine
> > > > >
> > > > >
> > > > >I have a slight problem that so far has never
> > > happened
> > > > >to me.  At 3/4 to full throttle and between
> 3500
> > > and
> > > > >5000 rpm the engine will cutout for less than
> 1
> > > second
> > > > >and then recover like nothing is wrong.  Any
> > > ideas?
> > > > >Plugs, wires, cap and rotor are all brand new
> > > stock.
> > > > >Injectors, filter and pump are also new or
> nearly
> > > new.
> > > > > It just seems to drop dead, but for less
> than a
> > > > >second.  It only happens once on any hard
> > > acceleration
> > > > >pass.  Never at an exact rpm.  Please throw
> some
> > > > >suggestions my way.  BTW, I'm loving the fuel
> > > mileage.
> > > > > It had been dropping for a while.  New
> injectors
> > > and
> > > > >ignition components seem to have worked
> wonders.
> > > 175
> > > > >miles to 3/4 of a tank and 500-600 per fill.
> > > > >Indicated mileage between 25 and 31 on the
> > > highway
> > > > >with some seriously hard driving.  Also no
> more
> > > 10
> > > > >sec. crank time.  Sometimes it starts
> instantly,
> > > other
> > > > >times on the second or third revolution.
> > > > >
> > > > >Thanks
> > > > >Jim Accordino
> > > > >
> > >
>