Away from home and losing power

Jim Green jeg1976 at
Tue Dec 24 08:00:12 EST 2002

--- Huw Powell <human747 at> wrote:
> > I drove my 1988 Audi 90 Quattro about 1000 miles
> to visit my folks near
> > Milwaukee, and now the car isn't running right.  I
> think the first symptom
> > is that the 'check engine' light started coming on
> after 20 min. or so of
> > driving.  It doesn't some on steady, but rather
> flickers at a high rate.
> > The car also seems down on power and won't rev
> over 4500 RPMs.  One known
> > problem with the car is the multifunction
> temperature switch/sender.  My
> > inside temp gauge does not read warm until after
> the car has been driven
> > for a while, and sometimes I think it reads low.
> I bought the car
> > recently and have not checked or changed the
> timing belt.  I do know it
> > has a new fuel pump however.
> Whatever it is, I think you should identify it close
> to home, and plan
> some alternate transportation for that 12/26 drive!
> It might "just" be a bad knock sensor, but I bet it
> isn't.
> Mine went bad, there were no symptoms.  Other than
> some knocking under
> hard acceleration on a hot day with a heat soaked
> engine.
> More likely, your engine is knocking, the sensor is
> telling the ecu, it
> is retarding timing - all the way back as far as it
> can - which makes
> the car rather limp in the power dept, and when the
> ecu retards all the
> way - it sets off the engine light.
> So for some reason, bad gas, overhot, whatever, your
> car is knocking and
> would like to knock hard, relatively.  The knock
> sensor/ecu seems to be
> protecting it from harm, but there must be a cause,
> you should find it
> before demanding a lot from the car.

Could be, but you would definatly be hearing it
knocking, or rattling, kind of like a noisy
distributer.  Even when I was abusing the sh*t out of
my engine at 15 psi and bad timing, I could never get
it to retard as bad as it does when the knock sensor
is disconnected or not torqued right.  The reason it
worked fine when cool is because it doesn't use the
knock sensor when it's in warm up mode I think.  I
often experienced this,  I thought I had the ignition
sorted out, then once the car warmed up the CIS-III
wants everything perfect, and it would go to hell.
You may be able to trick the car into thinking it's
cold by substituting in a resistor (don't know what
value right now) on the temp sensor input, then go for
a little drive to see if you are getting knock.  This
is what I would do, fill up your parents lawnmower, or
anything else with a Honda engine in it with your gas,
and go get some new stuff.  Or just top it off.  Then
I would really concentrate on that wiring and still a
new sensor.  I almost guarantee it's one of those two.
 You could rent a truck, tow the car home, and try one
of my sensors when you get back to CO.  Or are there
any 90q owners nearby who can lend a test knock
sensor?  Don't feel bad though, I started my car last
night for the first time in two months, and was
rewarded with a crack in my fuel rail, and a leaky
downpipe.  I'm going to put the tools away, go to the
mall and have a little chat with Santa about how all I
want for Christmas is my car back on the road!


Jim Green
'89 90tq 034EFI, Haltech IG5

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