misfire issue

[afilly]

Hey i have a 2000 a4 quattro 1.8t avant with a misfire issue. I was driving back from best buy the other day and as i came out of a roundabout i accelerated and then my car started shaking and running rough, after checking the check engine codes, the code reader said i had a misfire in cylinders 2 and 4, codes p0102 for mass airflow or volume circuit, which had been there previously P0300 for random misfire detected, P0302, P0304. After doing some research on here i learned that it would be uncommon for 2 ignition coils to go out at once which would cause 2 misfires. It idles rough and but rpm's bounce only slightly (because of MAF?) Could it be the spark plugs or wires, the catalytic converter, or could it be my bad MAF that could cause a missfire like that? I was going to go out and buy new coils and spark plugs today to fix it, but it would not be worth it if that was not the issue? Anybody know what this could be?

[redline380]

It's the Wisconsin air.

[afilly]

so ill just move to California and the problem will be solved? :D

[Rodgman15]

Yes

[redline380]

The only thing Wisconsin air is good for is cheese making and being drunk.


But seriously, look at the MAF. All that Wisconsin air probably fucked it up. And I'm sure like everything else in 'Sconsin, it is drunk.

[afilly]

i swapped the coils around and just have to wait till i can get a code tester and see if the misfires are different.Sspark plugs all looked ok, i disconnected the MAF and started it to see if it would run any different and there was no change from when the MAF was connected. Next step would be a new MAF perhaps. otherwise could it be injectors? Catalytic converter? i dont know what else to do.

[Radskull1]

i had this issue in my 2000 a4, the wires in the harness were starting to go, so every other time i would go somewhere and go around a corner it would randomly start missing. check the ends of the harness and see if the plastic inbetween the wires has cracked. the spark can jump over it and cause a miss its not the catalytic converter, I changed mine out when i did a turbo swap and it didnt change any issue the harness was at fault in my case, start at the harness i replaced all my coils and sparkplugs and it didnt make a difference, it wasnt until i noticed that there was a cracked "Tooth" between the wires in the harness which was fixed by taking some sculpting clay and filling inbetween it since clay is a non conductive material, after that the car runs perfect, still does but now has a bad transmission, hope this helps!

[TheGetawayCar]

I had a similar issue. Had a nagging misfire under load. I found that it was on cyl 2 only and that is usually indicative of a bad ICM. Now you don't have an ICM on a 2000 but I'll tell you how I went about solving it.

First, I shuffled the coils and the misfire stayed in the same place. Replaced the ICM but still had the stutter but a bit lessened. So, I shuffled the coils again, and the misfire started to move. I checked it on all 4 cyl and the (now weaker) misfire moved with the coil. So I replaced the offending coil and the car has never been smoother. I'd never heard of an ICM and a coil failing at the same time but it happened.

Yes, while it might have been rare in the past for two coils to fail at the same time, these cars have never been older than they are now. Also, later B5's with the 4-wire coils I believe are more prone to coil failure than the early style where it was usually the ICM that failed. So while unlikely, it's possible that you do have 2 bad coils. They are 16 years old after all. Nobody's ever had 16 year old coils in a 2000 B5 before, you might be the guy who discovers that yes, sometimes two go bad at once when they're old enough.

Some other things to think about: while I was chasing my misfire, I noticed that fresh plugs gapped very tight made it much better. For a while I thought the engine was just being a diva and demanding only the freshest plugs that it would devour in 1000 miles. It's much better with the new ICM and coil. Also you might want to check the coil grounds on the coil harness. There's a good chance it could be gross and impeding the contact for two of the coils when loads get high.