i have a 99 a4 1.8t with 80,000 on it. last week my exhaust starts to sputter and backfiring. it sounds like a motorcycle. i step on the gas and it seems to be reacting slowly. and the engine light is on. i replace the spark plugs. and i took it to a mechanic and he told me it was an a ignition coil. so i replaced that the engine seems cool. but the exhaust still back fires and the engine light is still on. i was thinking of replacing the rest of the ignition coils. but i dont know what the problem is. i don't want to take it to the audi dealership yet. please help me!!! i miss my baby!

 

might be valve timin or somthing wrong with the valves. seems like unburned fuel is burnin in the exhaust systme. it could be too rich also. feel bad about that bud. hope she gets well.

 

Best bet is to get it VAGed and find out what codes are being thrown, we all can give you ideas what it might be but a VAG will pin point it alot better like which cylnders are missfiring so you can make sure its the coil packs and not waste money.

 

the mal. function light is blinking. i read the manual and it says the catalatic converter might be damage or other emmision problems.

 

is the engine block shaking?
If so, check if all the cylinders are firing.
I got a problem like that abt 3 weeks ago. Sounds very similar to your problem.
For my 1.8T, cylinder 3 stopped firing. I had to replace the ICU since my car doesnt have any distributor.
cost me $140.. changed it myself within 15 min. (would hav been quicker but the place needed a good cleaning)

Good luck

 

thanks that might be it. my engine block is shaking. where do i find a icu and how do i install it.

 

do you mean ecu? two of my mechanics told me it was the ignition coil but they're not sure. they're not used to high tech german cars.

 

Its on the airbox, oval, held in by two hex head screws, and has two plugs going to it. You can find it at, ECS


[IMG]local://upfiles/1765/B5EC4AF48AB340E29822A45F4633EEC2.jpg[/IMG]

 

I don't mean the ECU. ECU should be fine... most don't break at all.
Look at the pic on the previous post. That is the one you need.
I got my replacement at www.stopshopanddrive.com
I needed fast so I had to pay extra shipping.
There is 2 brands for 1.8 (Huco and Bosch) and 1 for V6 (Breu).
I personally upgrade if I have the money so I got the Huco... works fine for me.
After changing it, it took me a while to start the engine.. I think I flushed the engine before (plus it hasn't been started for a few weeks).
Then for about 10 sec, the engine keep shaking.. then the shaking disappeared as I rev it up a little before it stall.
The check engine light was still on.
Regardless, everything seems fine so I went for a drive with my friend. Drove for abt 15~20 min and I found the check engine light went off.
Everything is fine until now... I changed mine on the 16th of Dec 05.

Before you buy and change it, make sure to check if every spark plug fires.
If willing to DIY, You can remove them (one by one or all the same time) and start the engine. you might want someone holding the plugs into the coil and be sure to ground the plugs.
Or you can always take the easy way and have the mechanic check it.
Unless one or more of the plugs are not firing, you don't need the ICU changed. Make sure the coils and wires are in good condition too.

Good luck

 

Pull codes.. dont drive the car... blinking CEL/MIL = dont drive your car...

im thinking your getting rapid missfires... either from the reason above.. or from bad coils..

check to see which are missfiring if any. Switch the coils around to see if that changes it. If the missfire changes when you move the coil most likely a bad coilpack.