'90 200tqs (MC) Cold start idle stability problem

Lundy, Andrew lundy at dmww.com
Thu Oct 4 11:35:59 EDT 2001

I'm not familiar with the motor on your car but here's things that I've done
with my cars in the past.

1)  Check ISV (if equipped)
2)  Check all coil/distributor/plug connections and wires.

If I knew your car better I'd tell you to replace the coil wire (but I don't
even know if your car has one).  I had a similar problem with my 928, after
replacing the ISV, and seeing a small improvement, I eventually found that
one of the coil wires was corroded.  I replaced the wire, and coil for good
measure, and the problem was gone!  Car is running much smoother than before
too!!  I would give all your *spark-related* wires a close inspection!!

Andrew Lundy
90 80q
99 A6q 

-----Original Message-----
From: G. O'Malley [mailto:vt_grego at yahoo.com]
Sent: Thursday, October 04, 2001 10:03 AM
To: quattro at audifans.com
Subject: '90 200tqs (MC) Cold start idle stability problem

I'm looking for advice on a cold idle stability

When I start my car after a long sit (say overnight,
all day) it won't idle for the first 30 seconds or so.

The car starts fine, cranks for only 2 seconds and
catches.  If I don't work the throttle, it will not
maintain RPM and stall......  I don't notice a miss,
it just won't maintain RPM.  If I work the gas, it
runs smooth.  

After 30 seconds or so (enough time for O2 sensor to
go closed loop; other?) the idle settles down and the
car runs great.
Runs great on warm start

The problem became visible when I replaced the
injectors, before that, I had to crank a long time to
get it to fire, and I may have ignored the problem.  I
really can't say....

I have reset the mixture since I replaced injectors.  
I adjusted the mixture with a scope, tweaked the
frequency valve to about 55% neg duty cycle.  This was
up from about 40% neg. duty cycle.  Little to no
effect is noted.  

I am at a bit of a loss on this cold idle problem. 
Overall (today, knock on wood) the car is running
great with the exception of this problem.... 

Recent engine related work includes.... Michelan man,
Fuel pump, Knock sensor #1, Lifters, 

any btdt's on this problem?
Thanks in advance,
Greg O'Malley
'90 200 tqs

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