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Rb26dett s13
01-18-2011, 06:42 PM
Why does my car keep misfiring? I have a 2000 A4, 2.8 Supercharged.

I ran the codes and I am getting intermittent misfiring on all 6 cylinders. All the air/fuel ratios are whack too. Only sometimes though....

It sounds like it is coming from the drive-train when the check engine light starts flashing and the misfiring is occurring. The misfiring doesn't discriminate either. It will happens during idle and going 120km/h and every driving style in between.

I have replaced the coil pack, all spark plugs, MAF housing, spark plug wires, vacuum lines, injectors and CTS (Coolant Temp. Sensor).

What else could it be?

I am getting tired of throwing money at my car and itís still not running properly.

Any help would be super helpful.

Thank you in advance.

Euromike
01-18-2011, 09:33 PM
First of all, Why are all the 2.8 guys getting supercharged?! I want one! Congrats man.

And about your misfire situation, Thats pretty tricky being that you replaced everything from the coils to the plugs themselves. Are you sure your plugs are gapped correctly?

When exactly does it misfire? is it near the same RPM range every time? only when the engine has load on it?

Rb26dett s13
01-19-2011, 09:48 AM
I think all the 2.8 guys are mutually tired of going slow.....[>_<]

The misfiring only happens the odd time.
Sometimes when I boost it, sometimes when its idleing, sometimes when I am cruzing at 110 Km/h
Once when I was just sitting in traffic. There is no constant behavior causing the misfiring.

It is quite a weird situation I am having here.

Rb26dett s13
01-27-2011, 09:34 AM
So I have pinpointed more atmospheric symptoms. Maybe this can help determine the problem??

1. The car never misfires when it is below -5 Celsius.
2. Today it is +1 Celsius and the car was misfiring like crazy for 5 minutes on the highway then stopped.

3. When it is below -5 Celsius and my car gets wet with snow or car wash nothing happens.
4. When it is +1 Celsius or above and the car is getting wet (car wash/puddle) it starts misfiring.

5. It doesn't matter if I boost it or not, it misfires during boost and not in boost.

Hope someone can help me out, I am really starting to hate my car.

somebody5788
01-27-2011, 09:38 AM
I hate to say it but those are classic symptoms of bad wires. Try spraying them with a bottle of water and see if it starts misfiring.

Mjan1992
01-27-2011, 09:51 AM
I hate to say it but those are classic symptoms of bad wires. Try spraying them with a bottle of water and see if it starts misfiring.


Agreed, and also sometimes you will be able to see sparks when you spray the wires with water

Rb26dett s13
01-27-2011, 10:37 AM
^^ What wires exactly? The harness? The CTS wires? What do I spray??

somebody5788
01-27-2011, 11:12 AM
^^ What wires exactly? The harness? The CTS wires? What do I spray??

Plug wires. I know you replaced them but that sounds exactly like bad plug wires.

somebody5788
01-27-2011, 11:13 AM
Though it's not normal to get it on all 6 cylinders. I suppose visually checking the harness to the coil would be a good idea.

rolsmi1
08-17-2011, 01:28 PM
I'm s/c'ed as well. Have replaced all parts you described + one O2 sensor,ignition switch, coil pack twice. Still sometimes misfires on same two cylinders intermittently, usually when starting from cold or idle. I have meth injection, so am going to disconnect the line to the manifold tonight to see if that helps. Remove your K&N filter, if you have one in. That always causes the MAF to fail.