10thCollector

I recentlly Came across a 2001 audi a6 2.7t quattro Rust free needing a few little thing.
the Seller just let it sit for 6 months unfortunately. It does drive well and sound amazing. the issue starts when well you try and start it it seems to Instantly drain the battery and you need a decent Jump to get it started. The battery was dead obviously so I drove it for a while Noticing all the dash lights even the taillights where pulsing rapidly. After getting it to my friends house it seemed to be ok I could turn the headlights on Ac radio adjust the seats and it was alright. when I shut it off the battery went dead almost instantly. With another Jump I headed on a 45 min drive home the Volt meter was a bit crazy while under load it would stay close to 14-15 volts the needle would drop down to 9-12 volts and shake wildly until going again.
I got it home and shut it off and it died again, after a 45 min drive at 60+mph should have fully charged the battery in it. I know the battery Is a good one It has been sitting in my truck for 2 months however it took a charge in my friends Jeep.

I Am leaning twords the voltage regulator on the alternator however since browsing this site could possibly be a ground wire or just the wrong
battery.

Anyone have seen this issue before? I could use some Guidance. this is my first Audi and have been waiting a long time to get one. this is the car ive wanted ever since I seen the topgear episode with the a6

johnkk

Voltage regulator in alternator is a decent hunch, but a pita to replace. I would get a VCDS (vagcom) scan first. You might have a short to ground somewhere or a intermittent relay issue that vcds might pick up. Of course check all the cables from battery and where they are connected.

10thCollector

It would be helpful to find a Diagram of where they are all the grounds are located, I Do not have access to Vagcom, I replaced alternators before on the same year pssats they are annoying putting the front end into Service position.

10thCollector

There Is an alternator in the trunk along with a few other parts. I Am going to be putting the front end in the air and checking the alternators connections it may be loose.

I am exited to get this on the road for me Ive owned quite a few cars and this is the newest car along with first luxury car and forced induction.

10thCollector

I Managed to aquire a copy of vagcom dianostics however I don't have the interface cable.
I had both batterys (one it came with and my trucks battery) on a trickle charger both charged up fine, the One it came with the starter solenoid would just click and dash dim and flash. my trucks battery would not make the solenoid click just dash went black.
Since removing the battery there was a rather large rats/ mouse nest undernath the battery tray.
I know the car will start with a jump off another vehicle however it should not need that much to turn over the engine right? I checked all the wires as best I could Positive wire leeds behind the ECU box the Negative just bolts to the cowl section which is fine.
I know audis are notoriously finiky but this issue should not even exist. I drove it a good 45 mins straight no issues on my trucks battery. however when I got home and turned it off it did not start at all dash went dim. Would Vagcom actually help with this issue? I am very new to audis ive only worked on them a handfull of times.
I need a car to get to work and back my daily (subaru forester) lost oil pressure and fried my rings on the freeway.

It is going to take 5-8 days to get the interface cable for my computer. I doubt the vagcom diagnostic will tell me anything as it does not start at all and ive probably rested the computer a handful of times removing the batteries.

10thCollector

Update: So I decided to fix the known issues with the Audi and after replacing cyl# 5s coil pack and giving my battery an overnight charge it seems to have cured the issues I have been having. I am not 100% sure yet on the charging up part but 10 start ups in a row with no drain and no odd flashing dash lights or fluctuations. so that might have been the culprit