Rough driving issues

A6 All/ S6 All
#1

I’ve been having issues with my 2007 S6 for awhile. I don’t drive it all that much during the week. On a cold start it just runs rough but that’s somewhat expected. Right now I’m just living with a check engine light. Its usually a misfire on cylinders 4 and 8. I’ve got all new spark plugs and coils.
Driving with the engine at about 2200 to 3700 rpm and I give it lots of throttle causes the car to hesitate like its misfiring. If I downshift a gear or two and brings the revs up then I don’t feel it. If I’m cursing at about 40 in 6th gear in manual mode and I floor it to load the engine up at about 1500rpms then it doesn’t have the hesitating feeling. If I’ve got a vacuum leak then I cant find it. Is there some place under the manifold to maybe look? Everything before the throttle bodies is tight and the oil separator hose coming from the valve covers is new. I’m lost on what to try next.

Went to get an alignment today and before I went I was checking over things with the vagcom reader. Here are two things I’ve noticed

Notice all the failed status. Does this just point to needing new O2 sensors?

https://scontent-atl3-1.xx.fbcdn.net/v/t1.0-9/65216787_10214805119254066_7313500320565297152_n.jpg?_nc_cat=100&_nc_oc=AQlZcoF9jXbSWXp2jSited8DdQvVwb3IknW2HMGA_A0cHGON9dhKxNOey654j9utssc&_nc_ht=scontent-atl3-1.xx&oh=f5a9fe27313e75e579ab247538f2dacb&oe=5DBA9323

I also went under the measuring blocks for the engine and chose block 32 and it does not show many any numbers. It has in the past. Is the ECU ignoring O2 sensor readings?

https://scontent-atl3-1.xx.fbcdn.net/v/t1.0-9/64971296_10214805119054061_6670073464679825408_n.jpg?_nc_cat=106&_nc_oc=AQmb2S2MJGURau7x3yVaMYoUunRlIPio_pKJkW9qMJ_oEz9sJajGD0uCxNWRAnaREj4&_nc_ht=scontent-atl3-1.xx&oh=8ab7158c187095ffec061d5d34e1dcc0&oe=5D870A1A

#2

If you have reset the codes in the Engine module recently, your readiness tests for evap and O2 sensors are going to read incomplete until you go through enough of a drive cycle(s) to meet the system’s criteria.

There is a single drive cycle pattern you can go through that involves different loads being applied to the engine at various rpms but just normal driving for a day or two should be able to satisfy the requirement.

Block 32 is your long term fuel trim. if you have reset your codes recently, they will be zero.

Check these blocks for your short term fuel trims:

#3

So last weekend I did some work on the S6. I’ve had some kind of vacuum leak and its been causing rough driving issues. Idle was horrible. Cold start was horrible. about 2200 to 3500 RPM under load resulted in horrible misfiring. I finally got tired of looking at the CEL light.

Ended up doing a carbon cleaning over the weekend. I had the intake off within an hour of starting while looking for possible vac leaks. The valves were not horrible. Two were worse than the others. So far I’ve done a carbon clean at 101k miles, 112k miles, and now at 126k miles. Got everything all clean and put back together and it seems to be running a lot better. I had some gold foil on the bottom of the intake and some small edges of the foil may have been touching the gasket mating surface. So I’m just guessing that may have been causing my vac leak issue. I’ve also got the JHM intake spacers. I have not had a chance to plug in my laptop to see what my LTFTs are but I’m hoping they aren’t at the +10% that they were before.

I know this has probably been discussed before but i’m looking at all this buildup on the valves and at the bottom of the intake. Is the crud coming from inside the cylinders back into the port or is it coming from the PVC system? I’m guessing its just through the PCV system. My oil separator is pretty new ( it is a cheaper version) but is it not possible to add in another type of oil catch can into the PCV system before the oil separator? Seems like I’ve heard of talk of something like this before. Any ideas?

#4

Just went for a test drive, cold start was bad again. I did sit for a minute with my laptop in the car looking at VCDS without the car running. Cranked up and it misfired on cylinder 8. It pretty much cleared up once it was warmed up. Drove for a little while and was hard on the gas and a the coupler that goes between the upper coolant hose on the passenger side and the radiator decided to break. Thankfully its just the coupler and thankfully I was only about 1/4 mile from my house and was able to get it back into the garage before the temp gauge even moved.

#5

When was the last time you checked or cleaned your air filter and the MAF sensor?
If it’s been a while it may be worth a shot, buy the MAF cleaner and if you have K&N air filter you can buy the recharge kit… (cleaner and oil). You’d be surprised what a little more air does.

#6

Try peeling back the coil pack wiring harness at the receptacle for the coil pack, because sometimes the coil pack receptacle on the harness goes to crap. Like I mean where the wiring attaches to the clip, which then clips onto the coil pack. Maybe that’s where you’re getting your misfires.

Sometimes the coil pack wires fray and crack right before they plug into the coil pack. When looking under the hood at the spark plugs and coil packs of your Audi, it looks as if there are no “spark plug wires” on a VW, but, there is such a thing as a “coil pack harness kit” or whatever, for replacing the wires that go to your coil packs (because they crap out).

Please let us know what the problem ended up being

#7

I just did a Google search for “audi coil pack wiring problems” and there’s lots of great info/examples on there relating to how these connectors might be what is causing your misfire, including a great video by HumbleMechanic on YouTube called “how VW parts fail 2.0t ignition coil connectors”

#8

And yeah maybe the MAF? Decent idea if you’re out of ideas. If the car can’t properly meter the air, then you can get misfires. And it might not show on all cylinders because all cylinders don’t necessarily have the exact same compression.

In the B6/7 S4/RS4 area of the forum, I started a thread called “Tiptronic Transmission problem Audi transmission problem / gremlin”. Similar issue to what you’re dealing with. Either way, I was chasing down transmission issues and intermittent misfire, so it might be worth a look for additional ideas.

In a nutshell, I had the car bogging down on me with no power until I got up to higher rpms. Then maybe a month or two later, it got worse and the transmission started clunking, and then it got worse and the transmission started slamming around.

More details in thread. Audi dealer recommended transmission service. Didn’t help.

Then in one swoop, I did the following and the car was like new again:

Throttle body cleaning, changing spark plugs, changing coil packs, and changing MAF. Then the following with Vagcom:

Transmission adaptation reset, for car to re-learn driving style and shift points:
http://www.ross-tech.com/vag-com/cars/autotrans.html

Throttle position “kick-down basic settings”, for car to re-learn Throttle Position Sensor (TPS) signals sent to the Transmission Control Module (TCM):
http://wiki.ross-tech.com/wiki/index.php/Automatic_Transmission_Basic_Settings#Kick-Down_Basic_Settings_in_ECM

Do a “throttle body alignment”, for car’s computer to re-learn throttle plate positions:
http://wiki.ross-tech.com/wiki/index.php/Throttle_Body_Alignment_(TBA)

No more misfire, and no more transmission problems.

Good luck, and please let us know what resolves the problem

#9

When doing the transmission bit, what password did you enter in security Access [16] for the transmission in order to get in to Basic settings [04]?

#10

Sorry for the dumb noob question, is that the Ross tech VAGCOM interface?

#11

Looks like it to me.