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My newly purchased car is a 1995 Audi 90 Quattro Sport with a 5 speed. The car runs great normally, has a few problems with such things as RF motor mount and the A/C system, which I'm working on. I am having a problem under acceleration that has led me to notice some other problems. Under heavy acceleration around 4000 RPM the engine will seem to hit a flat spot. The car won't accelerate, the revs will remain the same, and my foot is still on the accelerator. This led me to check out the engine some more, and I am now hearing an RPM dependent clicking, although I can't tell where it is coming from. I'm thinking valves probably. Also, during the checking of the engine, I noticed that from idle, if I hit the throttle a decent amount, the engine will make a very deep throaty sound, and some smoke will come from the tailpipes. I don't know if this is just how the engine works, if it runs rich at low RPM in order to give acceleration. There is also a whine that is RPM dependent, and I would describe it as air escaping from somewhere, but it could be anything I suppose. There is also a smell coming from the engine compartment, it gets stronger under acceleration, and is somewhat sweet smelling, but it isn't antifreeze. Any help would be greatly appreciated, thanks!!
 

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me too!

dude, i got the same freakin problem... lol mine is a 1988 audi 90 quattro, also 5-speed and it does exactly what you described except after a few monthes of driving it developed even more enigne problems ( i posted "car keeps dieing! please help" lol) id say im pretty choked at the amount of problems that this car has accumulated in such a short period of time.

good luck
 

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Hello,
a couple of questions about your symptoms:

- when you say "under heavy acceleration" do you mean foot to the floor? there is probably a full load switch somewhere on the throttle body that indicates to the computer that big acceleration is required so give more enrichment. If this is not operating or is badly adjusted then there won't be the fuel for heavy acceleration.
- is the problem evident at all engine temperatures?

The clicking could be one of a few things. The idle stabiliser valve makes quite a loud clicking noise; as you say the valves may be ticking (have you changed the oil recently, thicker oil helps the hydraulic tappets); the coil can tick but this is more audible inside the car.
The deep throaty sound is probably the second throttle butterfly opening, have you checked the air filter?
If you think there is air escaping from somewhere I would be inclined to try to pin point this as air leaks on the manifolds are bad news. I have recently devised a good method for isolating noises which involves a cheap funnel and a length of plastic tube. Fit one end of the plastic tube to the tube on the funnel, put the other end in one ear and insert an ear plug in the other ear. This has the effect of picking up noise only in the vicinity of the mouth of the funnel so point the funnel at possible things in the engine bay and see if you can find the hissing.

Good luck

Keith853
 

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Yes, foot to the floor. And it seems to happen more when the engine is warm, but I'm not real sure about that. I changed the oil yesterday after using an engine flush anti-sludge treatment, and the ticking at idle is almost gone. It still ticks at higher rpm's, but nothing major, just noticable if you have the windows closed and the radio turned way down or off. I have checked the air filter, and it looks clean. I'll try to pinpoint the leak, it is probably nothing though, just air moving where it is supposed to be. Thanks for the reply.
 
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