Re: high boost stumble

[Iain Mannix <mannix@privatei.com>]

FWIW, my 87 5kcsw is doing *exactly* the same thing.  I just installed
my Charlie Smith spring(so far, so good, with the exception described
below).  When mine gets to 1.5 bar for more than a second or two,
there is a slight hesitation, boost levels off & stays constant at 1.5
bar, but acceleration flattens a bit.  

My intercooler has a *slight* leak, which I've tried to recrimp - there 
is a mist of oil on the plastic shroud - my current theory is that the
i-cooler can hold the boost until that point just past 1.5bar, then
starts leaking - no additional pressure.  Have a new i-cooler on the
way, so I'll be able to test my theory - but I'm fairly ignorant,
could be way off the mark on this one.  

The car is fast up until that point, and will occasionally get to a
strong 1.6 bar, but only in higher gears/higher speeds(too high to
experiment with extensively).  I'll be curious to see responses to
this!


Iain Mannix


On Mon, 27 Dec 1999, Beer, Jerry wrote:

> Ok, list traffic is light, so maybe someone can help. Patient is a 1991 200q
> 20v, 160k.  IA3(about 2-3 years old), 2Bennett k24/26 hybrid.  When set to
> 16 psi per VDO via some spring shims(car gauge reads 1.8), car pulls
> cleanly. If I shim the spring to pull 20psi (car gauge 1.9-2.0), car has a
> flat spot anywhere between 17 and 20 psi.  Hard to describe- feels like a
> very soft rev limiter. For you "old timers". feels like a stuck needle in a
> needle and float motorcycle carb setup. If I get go pedal off the floor a
> little, it clears right up and car surges forward. The boost gauge seems to
> hold whatever boost level the car is at when this occurs.  Seems a little
> worse when car gets hot from repeated runs at boost, but it won't occur
> every time. Most runs are in the higher gears.  Both knock sensors recently
> replaced, plugs (F5dpor) relatively new.  WOT switch?  Fuel pump not flowing
> enough? (not terribly noisy).  Other than this problem, the car flies. No
> fault codes read out. Any WAGS?  TIA
> Regards,
> Jerry
>