Running less smoothly after car is warm???

[Brett Dikeman]

At 6:00 PM -0400 6/24/02, Robert Bane wrote:
>I am driving a 1989 100 Quattro.  When I first start my car and take off it
>goes smoothly up through all five gears with no hesitation.  However, often
>after this it can be very hesitant and seems to get bogged down.  It would
>seem to me that it is more normal for a car to run better after it has been
>run a bit rather than when it is first started.  Any ideas as to why my car
>is acting this way and what could be checked to get it to run smoothly
>throughout?  Thanks in advance for any ideas.

How long does it take to get into this bogging-down condition?  It
could be that the car is running fine in what is called "open loop"
mode, but after the O2 sensor warms up, it tries to run in
closed-loop mode(which is where the O2 sensor provides feedback
re:mixture to the ECU, which makes appropriate changes.)

When was the last time the O2 sensor was replaced?

How is the idle, both cold and after it has warmed up?  Should be
smooth, fairly stable, and around 800-900 rpms(spec is usually +/-
100 rpms.)

How are hot starts?  Any different from cold starts?

Been keeping up on your regular maintenance?

Any codes from the ECU?

Brett
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