winy68

My 05 A8L 4.2 had a ck engine light for about a day then went out on its own. She's also been running rough for a couple weeks. I took it to local shop that plugged in a computer and looked at the codes. Unfortunately they didn't save them. he said there was a handful of codes which indicated an Evap issue. he cleared the codes and asked me to come back when the light came back on saying he would be better able to diagnose the problem and perhaps blow smoke into the system to look for a leak.
Are there any common or typical areas that I should take a look at? It would be nice to find the problem on my own with your advice.

Thanks

mishar

In order to do that you have to perform your own VCDS scan and post it here.

Johnnyb2451

Have you changed the coils and spark plugs within the last 50,000 miles or so? My car was running rough for a while and got progressively worse.

BASARAB

on my D3 the evap codes would not go away until I changed muffler flex pipes, they were loosing air .
On B6 A4 they would not go away until evap canister was changed.
So get your VCDS scan and good luck.

winy68

Yes I had the big service where they changed the plugs filters etc. like you said I got it back running not great and its progressively worse. I thought it was transmission because I'm getting quite a bit of movement in the cabin, but it doesn't seem so. I also noticed my MPG has gotten bad as well.

winy68

will do thanks

I'm taking by a local shop tmrw, I'll have them rescan it, even though I didnt get a check engine light since they cleared my codes. He mentioned he can blow smoke into the system to look for a leak.

I'll post codes if any come up.

THANKS!!

winy68

Thanks

winy68

Doesn't look like an evap issue after all. He hooked up a smoke machine and no leaks. He then plugged in the scanner and it came up with the following faults.

16684 Random/Multiple Cylinder Misfire Detected P0300 Not A Plausible signal - Intermittent

16689 Cylinder 5 Misfire Detected P0305 Not A Plausible signal - Intermittent


My mechanic thinks I should replace the coil on cylinder 5. My car had a recall of the coils and it was replaced in 2010 according to the dealer who used to take care of my car.

Do you guys agree? If I'm going to replace one, is there any justification to do the rest while I'm at it? any higher performance options?

One last thought I'm concerned that there might be another issue, since my MPG has gotten so bad. Or do you think this would account for the horrible MPG as well?

Panelhead

I had this and replaced all eight coil packs and plugs. Did it in the driveway, about 250.00 in parts.
My car has a 2010 yellow campaign sticker also. Assumed this meant the car had eight of the replacement "T" coil packs. But on removal the car had two of the T series and six original CP. The failed one was an original.
Saved the two T series that must have been installed in 2010 campaign for future needs.
Want to think the car runs smoother, quicker, and gets a little better mileage. But it really seems to run like it did before the coil pack started acting up.
Look at yours. The T series have a T in part number, plus the black part on the top is slightly recessed. The old one are flush.

winy68

good info - Thanks