So I went to drive my 2000 s4 today when I got back out form the store I started it up and at low rpm you can feel a vibration in the motor. when you acclerate it gets worse and there is a huge power loss and the bad smell of stinky eggs that is really strong. Motor idles fine and starts no problems. So if this is the cats, would it most likely be the regular cats or the pre-cats in the downpipes? also, at higher rpm the check engine lights blinks, it has been on due to my 02 sensors, but when it comes back down to lower rpm it stops blinking.
thanks.

 

Well, blinking is bad. Most likely you plugged up the cats driving too rich. Something is wrong with more than just the O2's.

 

you have a misfire.. find out what it is asap and you might save your cats.. when the check engine light flashes like that it means that there is a catalyst damaging misfire present.. find out what it is and repair and you might save your cats..

 

How do I find out what it exaclty is I dont have a vagcom. I brought it to my mechanic and he said that it was the cats. He can the check engine light code back in sept. and it was the o2 sensors. He said the smell of rotten eggs and the way that the engine was running it would be the cats clogged up.

 

I'm guessing Ignition Control Module/s. Exactly what happened to my car, except my idle was still rough. Also could be bad plug/s, coilpack/s, possibly injector sticking. Hard to tell if you don't have a Vagcom or something that reads codes.

 

If i go to to the audi/vw dealer they will hook it up and read the codes and i will know what exactly is going on?

 

Yep, they should be able to read the codes and let ya know whats wrong. Luckily a Vagcom fell into my hands awhile back so I can easily read the codes. So what I did is just switch stuff around to see if the cylinder misfire moved at all. And whatever thing I switched, whether it be plug, coilpack, or ICM, that was whats wrong with it. But I know its definitely harder for you since you don't have the vagcom. I'm not sure how much youre dealership will charge. But the one near me charges $65 diagnostic fee, which then they tell you whats wrong.

 

go to autozone and have them read the codes.. if there is no definition give us the numbers and we/i can look them up and tell you whats up...

 

Crap, yea I forgot about that! Definitely do that instead!

 

OK. I will go to autozone and have them read the codes. They have legit stuff to do that right? I have a buddy who works there and im sure he will hook me up. They can read all the codes that the cell spoits out right? I know there are some codes that only audi can read.