I am new to the forum,but have been working on Audi 5000 and 100 series for the last 10 years.
Any help with my current problem would be greatly appreciated.

My 100 10 valve non turbo has developed a bad hesitation when taking off from a stop after a short pause (idile).This problem never occurs when the car is moving,only after a stop.It occurs with a hot or cold engine,although,the condition seems more pronounced during warm up.Once the hesitation passes I have very good power at all times.
Engine has factory rebuilt head and I have done recent tune up (new plugs,rotor button,cap,filters,timing,etc)

Any ideas? I have factory service books,but have yet to come up with any possible causes.

Welcome to Audi Forums trs6332!

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Did this problem begin right after the tuneup?
Manual or auto tranny?

Thanks for responding.

I checked the archives,but only found my post and one other.

tranny is auto and the problem developed right after or shortly after head replacement.I thought i had found the problem when I discovered a slightly loose harmonic balancer,which was causing the knock sensor to retard the timing,but I have fixed this and the problem presists.I suspect the problem is related to the injection system?

Good guess.
Also consider the tranny. I'm not familiar with your model and the systems, but something tells me that there may be a sensor that responds to throttle within the tranny. Consider that, too.

It's the fuel pump, replace it fast or it will die and you won't be able to start your car, as mine is doing now....

As I have mentioned before, do a volume and pressure test before replacing the pump. It's a PITA to get too and pump is expensive. If the problem turns out to be something else then you just wasted time and money. If the work is done by a dealer then it will be even more $$$$.

One possibility... I have the same problem with my 89 200T... The problem seems to lessen after the engine warms up. One possible cause is noisy lifters. The ticking noise can trick the knock sensor(s) into thinking that the engine is pinging. I haven't gotten around to replacing my lifters yet, but when I do I'll post on my results

Mike