1990 200 missing/lean under boost

[David Michael]

follow up to my previous post

I bought the coil in the top picture at:

http://www.partsgeek.com/catalog/1990/audi/200/engine_electrical/ignition_coil.html

In spite of the pic, it includes the coil, BUT you need to take the the new
coil and electronics off the frame then re-use the old frame.  Also, the
nuts into which the screws that hold the coil to the firewall thread are NOT
captive and will fall under the blower motor if you just remove the
screws......

On Thu, Jun 9, 2011 at 11:45 AM, David Yentema <david.yentema at gmail.com>wrote:

> NB is narrow band, its an afr gauge that just reads the signal the regular
> o2 sensor puts out. I pressurized my intake manifold up to like 15psi and
> found a few small leaks that I fixed. I know the injectors where replaced
> about 20k before I bought the car, and the ones I pulled had new-ish looking
> orings on them.
>
> We have a smoke machine type leak detector at work, and I really wish I
> could borrow it to see what's going on, but I'm just going to have to hook
> my compressor up to somewhere with the whole intake put together to see if I
> have any funky leaks
> On Jun 9, 2011 11:09 AM, "David Michael" <adavidmichael at gmail.com> wrote:
> > 53 psi sounds right. Problem I had was that it randomly jumped to 55 psi.
> >
> > I also replaced my dizzy because a bad Hall sensor was causing a
> mis-fire.
> > But again, it was not boost related - it happened all the time.
> >
> > Have you checked your valve cover gasket and injector o-rings - both
> common
> > sources o vacuum leaks (which will cause you to set your base setting
> > incorrectly)
> >
> > Not sure what "NB" is but at WOT, the system is running open loop, and
> the
> > 02 duty cycle goes the a fixed number (can't remember what - maybe 68%).
> >
> > A boost leak will usually result in black exhaust smoke ie - very rich
> >
> > Dave
> >
> > On Thu, Jun 9, 2011 at 10:49 AM, David Yentema <yentemad at rider.edu>
> wrote:
> >
> >> These were the fuel pressures I got last time I checked:
> >> cold control pressure 22psi
> >> warm control pressure 53psi
> >> system pressure 84psi
> >>
> >>
> >>
> >> On Thu, Jun 9, 2011 at 10:31 AM, David Michael <adavidmichael at gmail.com
> >wrote:
> >>
> >>> It's a long shot, but have you checked the control pressure? Moreover,
> if
> >>> you can safely do so, you may want to figure out a way
> >>> to monitor conbtrol pressure under boost.
> >>> The control pressure is supposed to be very steady after the car warms
> up,
> >>> but I had a control pressure regulatory go bad on me; it increased the
> >>> pressure (leaned out the mixture) by a few PSI randomly. The failure
> was not
> >>> related to boost, but if the control pressure is wrong, nothing will
> work
> >>> properly. Remember, HIGHER pressure means LESS fuel....
> >>>
> >>> Dave
> >>>
> >>
> >>
> >>
> >>
>