1999 A4, 2.8L engine, 5 speed Auto.
Engine starts after long crank. Then VAG-COM gives me a message: "Multiple misfiring all cyllinders"
Above 2500 RPM works smooth, has power.
Under 2500 RPM start misfiring again.
Tested with VAG-COM.
Error message: "Multiple misfiring all cyllinders"
Anyone has any idea what's going on??
Thank you.

 

is that the entire error code? can you post everything the VAG says?

 

I would suspect that you have a vacuum leak.

 

Thank you all for your inputs.
Error codes are:
*****
2 Faults Found:
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 35-00 - -
16689 - Cylinder 5 Misfire Detected
P0305 - 35-00 - -

*****
I pressure tested the cyllinder #5.
It was 60 psi.
The cyllinder next to it was 140 psi.

It looks like it is a bad valve or broken piston ring on #5.

Is there a way to find out exactly before disassembling?

Any ideas what may the costs be?

Thank you.

 

Put some oil in sparkplug hole #5. If compression improves it's the rings, otherwise the valves.

 

I had misfiring problem with my Audi 1.8T A 4. IT took the dealership a week to figure out what the problem was!! Finally they found Mass Air Flow sensor and O2 sensor's were failing.