struggling 5kcst

[Paul Meyers]

I just fixed a problem with the check engine light coming on at anything
above 0.8 bar. It was the inlet air temperature sensor located at the exit
of the intercooler. One of the wires had broken under the boot that covers
the attachment. It didn't affect performance in quite the same way as your
problem, though.

-----Original Message-----
From: Rokas Reipa [mailto:rokas at wam.umd.edu]
Sent: Friday, September 01, 2000 10:03 AM
To: quattro at audifans.com
Subject: struggling 5kcst


Hi all. For the past month, I've been having a rather peculiar problem with
my 86 5kcst(3sp a/t), namely that it struggles when accelerating on 80mph+
highway speeds. I remember the acceleration as being deliciously brutal at
those speeds not too long ago, but now it's gone. The problem starts
appearing at the upper 3000rpm range and continues all the way to the
redline. It starts surging noticeably(feels like the ignition timing is
being retarded) and the acceleration from 80 to 100 takes quite a while now.
Here's what has been checked/replaced so far: New michelin man hose, new
bosch super 3-electrode spark plugs, cleaned out the k&n air filter. I also
took out and thoroughly cleaned the injectors(two of them were badly gunked
up) and this helped noticeably but did not eradicate the problem. Error
codes indicate a bad knock sensor but I somehow doubt this would be
affecting the engine in such a dramatic way(Doesn't the knock sensor only
retard timing by 7 degrees or so?). Also, the check-engine light doesn't
always light up when accelerating, although it lights up often when the
stock boost gauge exceeds .5 bar. BTW, when accelerating at WOT, the boost
reaches 1.4 but it really doesn't feel that way with all the surging, etc.
Is my problem a bad knock sensor or could it be something else? TIA for any
help.
 
Rokas
1986 5kcst  151k and counting......

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