P0308 Misfire Under Acceleration

[SensoRS6]

It is misfiring under acceleration, and causing the Check Engine light to flash. Any ideas? And I really would like to fix this myself. Help would be great.

[DHall1]

Plugs or coil packs

It is misfiring under acceleration, and causing the Check Engine light to flash. Any ideas? And I really would like to fix this myself. Help would be great.

[SensoRS6]

Would it always misfire if it was one of those? Or would it maybe be the fuel pump, since its only under acceleration?

[lswing]

Tuned yet or still stock? Other work done recently?

[SensoRS6]

Just the TC has been done. It was doing it before I for my tune, just got it done over the weekend, so its not the tune. IT seems to be getting worse though. First time it did it was under full throttle, then a few days later it was doing it just under hard acceleration, and now its doing it almost under any acceleration.

[Zmey]

Plugs or coils, try to vagcom, and see if it shows you which cylinder is misfiring. Swap coils and see if the misfire follows to the cylinder you swapped with.

[SensoRS6]

Whats the process for removing Coil Pack? What needs to be removed to gain the access?

[10SecS4]

How many miles are your on RS6? Does it idle and drive ok normally when not under hard acceleration? If so, my first guess would be spark plugs.

[SensoRS6]

Hey Marc!

I havent really gotten to test the Tune yet because of the misfire, but from what I have felt, its a beast!!! 96k miles, idles and drives just fine, just when I get on it. And its only on cylinder 8. No code showing for any of the others.

[Dmb408]

You have to take the airbox off to do the tune up, it is hard the first time, but once you figure out how you are going to handle the driver's side 10mm bolt, it gets a lot quicker the next time. The pictorial in the DIY is good.

[as350]

Plugs or coils, try to vagcom, and see if it shows you which cylinder is misfiring. Swap coils and see if the misfire follows to the cylinder you swapped with.

^^^ THIS

It's the quickest and simplest step in trouble shooting. It sounds like a coilpack has gone bad.

[lswing]

Just the TC has been done.

Sorry to go off topic, but you didn't do the trans at the same time, and it's the original trans with 96k?

If that's the case I wouldn't dare put a tune on it as the trans has not got much life left...just warning, I tried to sit on my older trans at 85k and it lasted another year, then the $7k trans bill...

But you will certainly enjoy it more tuned!

[ben916]

You have to take the airbox off to do the tune up, it is hard the first time, but once you figure out how you are going to handle the driver's side 10mm bolt, it gets a lot quicker the next time. The pictorial in the DIY is good.

This is the right way to do it, BUT be very careful when disconnecting both the MAF sensors as the red/pink pin alignment guides get weak with heat and crumble apart = they fall down the rabbit holes (the intakes to the turbos) and ask me how I know . Cover the intakes with a clean rag. This entire process is much easier with two people.

[SensoRS6]

Sorry to go off topic, but you didn't do the trans at the same time, and it's the original trans with 96k?

If that's the case I wouldn't dare put a tune on it as the trans has not got much life left...just warning, I tried to sit on my older trans at 85k and it lasted another year, then the $7k trans bill...

But you will certainly enjoy it more tuned!

Just didn't want to throw more money at it at the time, and they inspected to see if there was anything wrong with the tranny, seems fine. Shift great.

[SensoRS6]

You have to take the airbox off to do the tune up, it is hard the first time, but once you figure out how you are going to handle the driver's side 10mm bolt, it gets a lot quicker the next time. The pictorial in the DIY is good.

Where is the DIY Section to find the step by step?

[10SecS4]

My old Mugello Blue RS6 has 230K+ miles on the original trans and converter, the last 25K miles of which have been tuned. 11.9 in the 1/4 mile with me, 11.7 in the 1/4 mile with Tim, zero issues, knock on wood.

Sorry to go off topic, but you didn't do the trans at the same time, and it's the original trans with 96k?

If that's the case I wouldn't dare put a tune on it as the trans has not got much life left...just warning, I tried to sit on my older trans at 85k and it lasted another year, then the $7k trans bill...

But you will certainly enjoy it more tuned!

[10SecS4]

I'd swap coil pack #8 with another coil and see if the misfire code goes from cyl #8 to the other cyl. Also, while you have the intake off and all apart, I'd install 8 new plugs. Stock heat range with my tune is fine.

Hey Marc!

I havent really gotten to test the Tune yet because of the misfire, but from what I have felt, its a beast!!! 96k miles, idles and drives just fine, just when I get on it. And its only on cylinder 8. No code showing for any of the others.

[lswing]

My old Mugello Blue RS6 has 230K+ miles on the original trans and converter, the last 25K miles of which have been tuned. 11.9 in the 1/4 mile with me, 11.7 in the 1/4 mile with Tim, zero issues, knock on wood.

That is amazing, and seems like there are a few others out there with long term success. Like with anything, the amount of care and upkeep really make a difference, hoping for at least another 100k off my rebuilt one...