Ok, i have an 01 a4 1.8tqm. The car is bone stock. Yesterday I was driving home, I got on it a little bit and my CEL started flashing and I noticed a miss-fire. I ran the codes today and the codes were p0411 (secondary air injection system incorrect flow) and p0301 and p0303 cylinder 1 & 3 Miss-Fire. any ideas on what would be causing this?

 

Start with spark plugs, replace them.Swap coils 1 & 3 with 2 & 4.
Reset the codes and see if they return.

 

Ok i did that and the plugs looked fine, i swaped the coils and it still miss fires.

 

Did you change and check the gap of the new plugs and is the misfires still in 1 and 3 or are they now in 2 and 4?

 

the plugs have like 200 miles on em... and the gap is where its supposed to be.. the shop that did my timing belt put in the plugs. also the mis fire stayed on 1 & 3.

 

could this be caused by a vacume or boost leak?

 

Swap the ignition coils for those cylinders.

 

i changed all the coils that did not work.

 

<sigh>

P0411: Something is wrong with the system that injects secondary air during the first 30 seconds or so of startup to warm up the cat quicker and reduce pollution. Serves no purpose other than to reduce pollution.

In my particular case, I got the code and actually googled "P0411" to find out you should first check all your vac lines for leaks/holes. I didn't even have to go beyond that since I found the culprit leak right near the combi-valve. I patched it with duct tape until I can get in there and replace the hose. The code was cleared and hasn't come back.

The misfire might clear up after that but if not, the possible reasons have already been covered. Who gapped the plugs and what is it? you said it's where it shoudl be but how do you know?