luvdubs

I did it again. I’m old enough to know better and I bought another Audi with unknown history. In my defense it was only $700 and it’s purty! It gives code for cylinder 3 misfire and random misfire. It had a stored code for low pressure fuel sensor. I swapped in new high and low pressure fuel sensors and had four new coil packs which I put in 3,1,4, and 5. Cylinder 3’s coil was covered with oil when I pulled it, as was the spark plug in that cylinder which I also replaced. I replaced the valve cover gasket on that side as well, just in case that’s where the oil was coming from. The car will start with a little help but won’t idle without pressure on the gas pedal. It runs rough at lower rpm’s but smooths out above 2500 or so. The CEL comes back after clearing the code and goes from solid to flashing and back while the car is running, still the cylinder 3 code. I know this car sat for almost a year and I’ve filled it with fresh fuel. Any thoughts?

luvdubs

Duh. 2006 Audi A6 Avant Quattro, 3.2 automatic.

kelisko

The exact same thing happened to my cylinder 5. Same exact symptoms. It turned out to be a loose injector connector.

In fact I got in there to clean carbon deposits. While pulling out the lower intake assembly on bank 2, two of the injectors 4 and 5 came out with it. I had to disconnect the injectors plugs to be able to take the assembly out and I broke the plugs tabs while doing it.

After realizing I had the wrong tools for the job, putting everything back together and going on a test drive, what is happening to your cylinder 3 happened to my cylinder 5. The next day I pulled out the upper intake and I found the injector 5 plug broken and loose. I firmly connected it and it fixed the problem.

The moment I pulled the bank 2 lower intake: youtube.com/watch?v=8oGFhyIoIrg&t=0h31m20s

What happened during the first test drive: youtube.com/watch?v=8oGFhyIoIrg&t=0h43m53s

Finding the broken/loose connector and connecting it back: youtube.com/watch?v=8oGFhyIoIrg&t=0h44m54s

beep-beep

I have one of those with 210K miles on it and no problems.

hrc4u

For me it was a bad injector..
What does your fuel trim numbers say? 🤔
Cheers /H

luvdubs

I can try to figure out my scan tool so I can check that out.

luvdubs

I also found this vacuum line broken but surely that couldn’t be the source of my issues?

luvdubs

My reader shows codes: P0303, P0301, P0305, P0300, and P0306. That’s cylinder misfire on 3,1,5,6, and a random cylinder misfire.

kelisko

If multiple cylinders are misfiring, that changes everything. And if a vacuum hose is broken, you have to fix it and test the car before pointing fingers to anything else.

The picture below shows my upper intake removed. It seems the vacuum hose you are holding is identified by Hose 4. A second picture below I took this morning may help you locate where it should be connected.






Here is the video that first picture was extracted from. That may help you have a better look: youtube.com/watch?v=8oGFhyIoIrg&t=15m20s

kelisko

Another view: youtube.com/watch?v=8oGFhyIoIrg&t=46m46s