My engine (2000 1.8t) started missfireing about a month ago ONLY when under moderate load/half throtle or more. I scanned the ecu and it was cyl. 2. I swapped cyl. 2 coil pack with cyl. 3 and the missfire followed the coil pack. So i replaced the coil pack. 2 weeks later i get another missfire on a different cyl. so i replaced all coil packs (yesterday actually.) All of yesterday the car drove fine. Now, again, it randomly missfires only under moderate to heavyload, but this time it didnt trigger a missfire code or flashing CEL like it did before. I tried my hardest to get it to do so and it had to have missed 10 times yet didnt trigger anything. I replaced the MAF and plugslast summer. I logged block 32 for the 02 sensorand monitored things with vag com and nothing seems abnormal (at idle.) I havent yet logged anything while driving.. Last time it missfired i got a 17521 code (02 sensor internal resistance too high) along with the random/multiple missfire code. Im guessing thats because when it missed, unburnt fuel/oxygen got into the cat and caused a crazy signal. Can a bad 02 sensor cause a miss fire? The voltages seem fine for it in vag com, but im lost. There is no ICM for 00 the ecu controls the fireing so i guess it could also be the wires, which would really suck. Sorry for the drawn out question but do youguyshave any ideas? I have 84k miles btw. I just spent $100+ on new coil packs so i dont want to replace an 02 sensor for another $100+ and have that not fix it...

 

Are you chipped?

If the ECU isn't throwing any codes, I'd gradually
get on the gas. Don't accelerate hard for a few days.
The ECU may have to readjust to the new coils.

 

ya im chipped, GIAC... Is my signature picture not working or what?

 

lol its working. but that sucks that your still having probs... if it makes you feel any better my turbo has about an inch of play in it and I ordered a custom new one for $2500 and it came today but ups dropped it and bent the comptressor output and it turns out the company i bought it from "forgot" to put shipping insurance on it and i have a feeling its going to be a bitch trying to get another out of them cuz they are the ones that fucked up.... lol sorry to rank and steal your thread but maybe my misfortune might make you feel better

 

Wow sorry to hear that... Hope you get it resolved... I wonder if my injectors are bad????

 

injectors will cause a missfire. I had a 550cc injector fail on my DSM and it missed like crazy. It was very noticeable that something was wrong tho............

Maybe pull the battery and clear the car, then see what happens? It seems to me that your plugs (or a plug)are fouled but IDK cuz I'm not there. The bad coil could easily cause theplug to foul out.

 

32 is your long and short term fuel trims. The o2 readings are 34-39. Check blocks 14,15,16. Those are for misfires. 14 line 3 is total misfires. 15 is misfires on cylinders 1-3. 16 is for 4-6. Are you sure you arent getting surging. Check blocks 100-120 for boost readings and n75(wastegate control vavle) readings.

Inch of play huh. Usually when you have that much the turbo shaft has broken. Usually the cause of that is low oil flow. Make sure you replace the turbo oil feed line.

 

Thanks.. Ya im about to go out and pull my plugs. Last I checked about a month ago they looked ok though. I have a set of bkr7e that im gunna put in and see what happens. I have bkr6e in there right now which is what i really should be using. If the bkr7e helps ill just get a new set of 6e's tomorrow.
But im still trying to make sense of the 02 sensor thing.. Can a failing/lazy 02 sensor cause a missfire?

 

Well I changed the plugs to the bkr7e and it seems to be fine now. Although, as I stated in previous threads about bkr7e, they are slightly sluggish due to being one heat range cooler than the bkr6e and they arent really meant for a chipped k03 but more for a k04 setup or more.. Anyway, I took my camera out to take a pic of my old plugs and ended up taking a video instead. Here ya go:

http://media.putfile.com/00-A4-18t-
Again (ateurv8) these plugs make the pickup down low more sluggish, so this isnt meant to impress anybody... Ill try to take a new video when i put in the bkr6e's to show the difference tomorrow. At least its not misfireing anymore, andyou can hear my Milltek growling!

Oh wait wtf i forgot i took a pic of the plugs duh:
The ceramic looks pretty burned up but they dont look TOO bad i dont think? They only have about 4k miles on them if that.


[IMG]local://upfiles/10408/16D852BB78D0482BA98BEE8C36212F96.jpg[/IMG]

 

nice little vid man