'91 200TQ - 'hiccup' when accelerating?

[Tom Donohue]

----- Original Message ----- 
From: "Bart Oleksy" <barto at nerdshack.com>
To: <quattro at audifans.com>
Sent: Tuesday, March 28, 2006 2:30 PM
Subject: '91 200TQ - 'hiccup' when accelerating?


> This is the long-running saga of my '91 200TQ (10-valve) that's had some
> hard-starting problems for a long time now...but something new has
> appeared lately.
>
> After replacing my Michelin-man turbo hose (and some other vital part,
> will confirm that later - oh, TPS!) the car was running better and not
> stalling at lights (!), but I noticed when accelerating hard, the car
> would give a very quick 'hiccup' at around the 3000-3500 rpm mark in
> 2nd, 3rd, and I think 4th as well...by 'hiccup' I mean the engine would
> just cut out for a split second and then continue as normal.
>
> It's *possible* it was doing this earlier and I didn't notice, as it's
> pretty close to where I usually shift to the next gear anyway.
>
> Also doesn't seem to do it with a gentler acceleration into that same
> rpm zone, nor have I managed to get it to do the same hiccup in 1st
> gear, which I brazenly got up to 5500 rpm with no side effects.
>
> Hard starting symptoms: Latest is that when it's been sitting outside
> overnight (Edmonton, Canada, so freezing to lower) it starts very
> quickly, but after several hours of sitting in a heated underground
> garage at work, it can take a LONG time of almost-catching-but-not-quite
> to get it to finally *start*.  Usually starts up right away within 10-15
>  min. of turning it off as well.
>
> Mechanic has replaced a number of things related to the hard starting
> thing (fuel pump check-valve, throttle position switch, some intake hose
> that had a small hole in it) with only minor difference, and is now
> suspecting that the injectors are leaking down.  These were supposed to
> be *very lightly used* injectors when replaced about a year ago by
> another shop, so I was hopeful that those wouldn't be the problem.
>
> Oh, and fuel pressure as measured "right off the head" stays steady,
> says the latest mechanic.
>
> Any thoughts/suggestions on things to look at for the 'hiccup' thing and
> hard starting issue?
>
> Thanks to all.
>
> Bart
> '98 A6 QA
> '91 200 TQ
> '86 CGT


Bart...I have been wrestling with a similar problem in one of my '91 TQA 
20-valves (I have 3 at the moment).  Have not come up with an answer but 
would be interested in finding out whether this is a known symptom in both 
the 10Vs and 20Vs.  Tom