it's still hesitating

Phil Rose pjrose at
Tue Jul 30 12:01:14 EDT 2002

>At 3:22 AM -0400 7/30/02, Audi Sport wrote:

>The hesitation is always evident no matter what the gear is or the throtle
>position. It just runs pretty rough. Like it holds back instead of
>accelerating and moving forward. Whenever I stomp on the gas instead of the
>car rocketing forward it just keeps bucking,

could be ignition-related--such as misfiring due to damp (and old)
sparkplug wires. Or a bad distributor cap. Is the problem usually
worse in rainy weather or in the morning--when the engine might be
cool and damp?

This does _not_ seem to be the more-subtle surging caused by a bad oxy sensor.

>I haven't checked any codes because I don't think
>there are any

Is that because you know that there's a good "Check Engine" lightbulb
installed, or are you psychic? :-)

>  I do know about the stock digital
>gauge being inaccurate but if the car makes 1.8 bar it should really show.

Really? What's _your_ definition of "inaccurate"? Also, are you
testing for maximum boost according to the recommended (Bentley)
procedure? [use 4th gear, cruise to about 2000 rpm and then floor
throttle--noting boost value attained by the time that 3000 rpm is
reached.] Doing this on a slight uphill grade improves your chance of
seeing a bit more boost developed.

>About the fuel filter, I have no idea how old it is. For all I know it could
>be the one it came with out of the factory. It wouldn't hurt to replace it.

Yep, probably cheaper than all those injection-cleaner treatments. A
very clogged fuel filter could cause your hesitation/bucking
symptoms. If you don't know its history, it's always wisest to assume
the worst and replace that filter.

>Which reminds me, is there
>any way to test any of these engine components that could be causing me

Well, one place to start is with the engine codes. ;-) There is also
a set of "output" tests, initiated by the ECU, which gives you an
audible indication of operation for the various components having
solenoid valves (each injector, wgfv, carbon-cannister valve,...) See
Scott Mockry's website for how to do that procedure. In my limited
experience, faulty ignition components are found usually after
trial-and-error replacing (or if you're lucky and happen to spot some
electrical arcing from a sparkplug wire, etc.)


>Antoher thing I just remembered is that the car does sometimes run
>pretty good and other times a lot worse but most of the time it just runs
>pretty ruff in general. And you haven't said anything about the bypass I was
>asking about. Do you think that could cause these problems or you haven't
>mentioned it because it's not really related?

A bad TBV (or TBV hose) could cause a loss of boost and some stalling
problems; but not, IMO, related to the hesitation symptoms you


Phil Rose
Rochester, NY
mailto:pjrose at

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