Ok I have a 99 A6 2.8. The check engine started blinking and the car started sputtering. The codes are PO305 PO300 PO301. The car has near 200K on it so I started replacing parts for my own piece of mind. It got new plugs, wires, coilpack, and injectors. After replacing all that it didnt change anything. Still runs rough and the CEL is still blinking. What else am I missing or what else could it be?

 

Since it's only one cyl on each side, can pretty much rule out any cam timing concern. My next step would be to do a compression test and see if those two cyl's are significantly lower than the other four. Another thing to check is make sure those injectors are actually being triggered. A quick way is use a piece of hose as a stethescope. Put one end on the injector and the other to your ear, you should hear the injector clicking. If not, check the voltage to the injectors (should be B+, 12V on one wire) and then check the other one for a pulseing signal (best to use a test light). The ECM grounds the injector to fire it, all the injectors have a common battery voltage circut with a constant 12-14V whenever the key is on. Aside from that, you've covered the common causes (plugs, wires, etc). There's no common problems or failures with the 2.8 that I can recall off the top of my head right now.

 

Thanks so much for the reply and the help!!

So I can just turn the key on and check if the injectors have voltage?

I will check it out in the morning. Thanks again.

 

Try replacing your ignition modules.

Bob

 

Sorry to sound dumb but what and where are those?

 

If I'm not mistaken (brain a little fried right now), the are the little boxes on top of the intake air filter box

 

I have nothing on my filter box?

 

Looks like your ignition modules are part of your coil pack and you already replaced that, so, never mind!

You can turn the key on and the injectors should show 12v on one side of the connector. The other side is grounded by the ECU. Since you have issues in two cylinders, and since injectors are fired in pairs (but I confess I don't know the pairing in the Audi) you could have an issue with the injector driver on the ECU. Have you tried the stethescope test suggested above? Can you hear the injectors cycling?

Bob

 

I did check the injectors for 12v and they all have voltage. I tried to listen to the injectors and they are all clicking. I am stumped?