Filled up Monday, and less than 10 miles ib two short trips. The car sat for 3 hours, then as soon as it started, it idled rough. Lopey idle, sounded like one of my old Barrcuda's or Challengers when the chokes would stick closed.
Drove home and acceleration had bad misfire and rough running. Yellow engine light would flash when accelerating from a stop.
Added a can of B-12 and next morning it ran much better, but not fixed. Drove the 60 miles round trip to work and the yellow light flashed a few times, then stayed on. Rest set while at work, came on leaving the parking lot.
The car runs better when the check engine light is on. Sometimes feels normal. But idles rough on start.
Topped off with gas from another station and added another can of Berryman B-12. then ran these scans. Also made an appointment to Bar Tuning for Monday in case it does not fix itself with injector cleaner.
Does this look like a bad gas issue, or do es it appear to be a real problem
ddress 01: Engine Labels: 077-910-560-BFM.lbl
Part No SW: 4E0 910 560 J HW: 4E0 907 560
Component: 4.2L V8/5V G 0010
Revision: -------- Serial number: AUX3Z0D8750390
Coding: 0007773
Shop #: WSC 02313 785 00200
VCID: 285FF7779BE9715EF37-807D

2 Faults Found:
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 001 - - MIL ON
16685 - Cylinder 1
P0301 - 001 - Misfire Detected - MIL ON
Readiness: 0010 0000

----------------------------------------------------

Sorry, the TXT file had three scans and is too big to upload. But this is the only result that was not normal. I idled the car for 20 minutes and scanned three times, the check engine light only flashes when accelerating. Idled like normal after the second can of B-12.

 

1) You should not be driving a car that's flashing CEL

2) Most likely lost a coil pack. Swap another coilpack to cylinder 1 and see if the misfire follows. Bad gas will give you misfire on all 8.

3) That B-12 stuff won't do anything, I assume it was made to clean varnish off carb bowls. If you're looking for an injector cleaner that will actually do something on modern cars, it has to contain Polyether amine (PEA). Chevron technron and 3m both make one.

 

First fault is random/multiple cylinder misfire. I hope it is gas. The B-12 was used to potentially absorb water. I am going try again Friday when back home. The 2nd fault misfire on cylinder 1 worried me. First engine faults I have had. But only have put 5000 miles on car.

 

Hi,

The first thing I would do is check the coil pack but I highly recommend not to drive the vehicle or you could create a bigger problem than you have.

What year and model is the vehicle?

 

It is a 2005, a8 Base. 4.2, 40v. It only showed the code the first scan. The next two came back clear. Ran three scan in 20 minutes or so. It idled perfectly during the scans.
Have not driven since. I should be back tomorrow evening. Will try a round the block before going to far.

 

Most obvious is a simple coil pack...or it's underlying spark plug. You should confirm your car got the coil pack service update/a.k.a. recall done. If not, an obvious trip to dealer and freebie. If already done, coil packs are relatively inexpensive now anyway.

Your description of the loping idle at one point also caused me to think about the cam sensors, but you didn't show/indicate any codes for that. Most generally, figure it is probably ignition, but could also be in some other sensors for ignition or general engine. VAG COM should point to the latter, which it doesn't seem like so far.

 

We carry the ignition coils as well as the spark plugs for the 2005 A8 4.2 V8.

Here is the link to the site for both parts:

AutohausAZ - Ignition coil

AutohausAZ - Spark plugs

Disclaimer: Make sure to check the year and model of the vehicle before placing an order.

 

Well I will take your advice and look at replacing plugs and at least one coil pack. The problem sure feels like a fuel problem. The missing when accelerating and good idle is consistent with a fuel problem. Feels like it is running rich.
I will test drive tomorrow night. It still acting up I will take it in Monday to get a local mechanic.
On the possible recall on coils, should I ask dealer over phone? I have a 200.00 key on order from them.

 

1. Ask dealer to look it up; likely a service advisor in the service dept.
2. Try contacting Audi USA: Audi Customer Service - Contact Audi | Audi USA There used to be an open service action look up on their web site at http://www.audiusa.com/us/brand/en/o...in_lookup.html, but I don't see that now. You could mention that to them on the phone.
3. Try looking under the hood for a campaign sticker; mine has a quite small yellow colored stick on label.

 

Missing when accelerating is a classic ignition problem. Like pervious post, its probably a bad coil. Check to see if your coils have been replaced under the recall with an Audi Dealer.