[s-cars] Need time for S4, help me fix my 200!

[Charlie Smith]

Earlier, Rich Assarabowski wrote:
>
> Not strictly S-car related, but the sooner I fix this one the more time
> I'll have for the S4!
>
> My 1990 200q suddently started running poorly.  Engine runs fine when
> cold for about the first minute, then idle becomes very rough, stumbles
> at the slightest application of the throttle and has very little power,
> car is barely driveable.

Make sure you don't have an air leak after the air flow sensor
(flapper plate assembly), before the throttle body.

On the 5kCSTQ the blowby hose which goes from the lower left side of
the block up to the intake manifold is prone to develop a split on the
backside - and it causes similar symptoms.  But, since your idle is fine
I assume the leak in in the intake before the throttle body.

If your O2 sensor system is working OK, it should correctly richen
the mixture to compensate for the leak ...  after you've held the throttle
steady for a second or so.  If the problem diminishes after a second or two
of steady state throttle, this also points to an intake system air leak.
The symptom "stumbles at the slightest application of the throttle" sounds
like this is what's happening.

    - Charlie


  Charlie Smith   charlie at elektro.cmhnet.org  614-471-1418
  http://www.elektro.com/~charlie      Columbus Ohio   USA
  http://www.elektro.com/~audi     photos & technical info

  95 S6 Quattro  -  24 PSI, RS2 6 speed, and other features
  96 Dodge Ram   -  30 PSI, w/Cummins turbo diesel