Like onepoint8tee said, go to Autozone and ask them to come out and scan the car. Out here in Colorado, Checkers lets you take the scan tool out to the parking lot if you leave your drivers license with them. They won't let you take it with you, but you only need it for two minutes anyway. Using a scan tool is so easy and straight forward.

Swap the coil packs from 1 and 2 with coil pack 3 and 4. Take note to which went where. Take your plugs out at the same time you swap the coils (making sure you put them back into the same cylinder that they came out of). Check the gap and condition of the plug and replace and or gap as needed. Go to the parts store and clear your codes. Drive around for awhile and then go back to a parts store and recheck the codes. If the codes show that you now have missfires in cylinders 3 and 4 it is the coil packs. Replace those two and enjoy. If not, you will need to do some more testing, or just take your car to a German tuner/repair shop.

 

He said the car is uninsured, which is why he won't drive to az.

 

If the misfire doesn't follow, could it possibly be a stuck intake valve? I'm not trying to scare you at all, but a buddy of mine said it could be a possibility.

 

one autozone near me lets me walk out of the store with their scanner just by asking for it, im surprised each time cause i could just as easily drive away. another autozone makes you leave your drivers licence as collateral. i doubt you need a deposit if your just pulling codes in their parking lot.


edit: ah nvm then

 

I have a 02 A4 1.8t quattro and am having the same problem. but I am having random missfires on cyl. 1,3 and 4. I also have a 0420 code. My valve cover seal was leaking coving the plugs with oil so I replaced that and put in new plugs and gapped them to .032. after the new plug were in it ran extreamly smooth and the missfires seemed to get less but a day later it was back just as bad. it still only does the missfire randomly and seems to get worse as the car warms up especially after a warm start.

Before the valve cover seal replacement I had random missfires on all cyl.

I am going to swap the coil on cyl 2 and see if the non missfire follows but I have a feeling its not going to matter. I have searched the site for quite awhile and see a lot of people seem to have this problem but I have not seen one that has actually fixed it. all the threads seem to end with no solution.

after swapping the coil and if the missfire doesnt follow I am going to check the compression. unfortunately I dont have the place or the knowlege yet to do it myself so I have to take it to a garage. I am new to posting on the site but have been searching the archives for quite awhile. As with everyone money is tight but if I am going to replace something I usually will try to replace it with an upgrade. Not thread jacking here just saying I have what sounds like the same issue.

Thanks

 

This is an old thread, but whatever, I guess. First things first: What gas do you run?

 

1- your car is a B6 not a B5, they are sort of similar but also vastly different. you may be better off asking the B6 guys.

2- try a smaller gap and see if you have the problem still, like .030 or .028.

3- you dont know if swapping the coils will do anything before you try, so go do it, dont make up your mind first that nothing will happen.

4- that P0420 (catalyst below efficiency) code is because you drove around with a misfire and melted your catalyst. you need to replace your catalytic converter now. after you fix this problem anyways.

your MAF may have failed causing part of the misfire, then after you drove around like that it ruined an O2 sensor making it worse. i would look into those two things if swapping coils doesnt do anything. or maybe one coil went, and then took out the O2 sensor after a few days of driving like that. is the P0420 code the only one you have?

lesson of the story: dont drive on a misfire, you cause more expensive damage.

 

P0420 isn't necessarily a bad cat. Fix the other stuff first and see if the code stays. Unless the cat's become a restriction. And also, it could have gone the other way around - cat becomes clogged and makes misfires happen. Also, a bad O2 sensor (usually rear, but either/any can do it) can do that. And yes, it can do it without throwing a bad O2 sensor code.

 

first of all sorry for refreshing an old thread but it the general issue seem similar to what I have. I had found the thread in searching and didnt see what section the thread was under.

I run 93 octane. I had recently bought the car and on the way home from picking it up. I scanned it and the only code that showed was the P0420 code. going the cheaper route I replaced the downstream O2 sensor. the code dissappeared for about a day and then it appeared agian. This was not due to the drive cycle as I had it done right before an inspection and I have an emissions check. So the garage drove it around until it was reading. a little while later the miss fires started. First just a little studder and then the got a little worse.

I reset the codes last night and drove around a little while (which I know I shouldnt but I have no choice) and the check engine light didnt come on until after it started to missfire. I haven't scanned it agian yet to see if it was the same cyls. I will be doing that this morning.

Thank you, next time I will pay more attention to what section the thread is in.

 

fuel injectors?