Well, only had the car two weeks, but have two constant issues and a new potential problem popped up this morning that scares the hell outta me.

1) Constant droning sound at 1500rpm w/ A/C on. Any ideas?

2) Diesel sound at start-up. I changed oil & filter and it's much shorter now - only a sec (use to be about 3), but I know that's usually a lifter issue. Expensive to fix? Is it something I should be worried about or is it okay to be left as is?

3) Alright, the new one this morning. Started the car up and put in reverse to back down my driveway. It took about 2 full seconds to go in reverse - that struck me as odd. Then, when backed out and put it in Drive, the car slammed into gear - hard enough to jerk my head back. It was also verrrrry sluggish to accelerate. I put it in neutral, back to drive - same thing. I stopped, put it in park and then back to drive - same thing. That's when I noticed the PRNDS indicator in the center display didn't show any gear selected. I shut off the car, restarted, put in drive and this time it showed the car in Drive (lil box around the D). Car ran & shifted great and after multiple restarts, the problem hasn't repeated itself yet.

It sounds like a limp mode, but I thought the PRNDS flashed or something when there is an issue? Is this just a freak accident or should I be worried?

 

1) Does it do it without the AC on?
If it doesn't, maybe your blower motor needs either cleaned or...replaced.

2) Diesel -like sound at startup that goes away is caused, according to Bentley manual, by the two check valves in the valley pan.
It surely can also be the lifters. If that's the case, they're actually fairly easy to replace (they just slide out and back in), but you'll have to take the camshaft(s) off. It makes also for a wonderful opportunity to change AT LEAST your cam seals, plug(s), if not the TB, T-stat and Water Pump.
If are the non-retention valves in the valley pan, you only need to take the manifold out (good opportunity to change the intake manifold gaskets - manifold to cyl heads).
The noise also can be caused by a slight disparity in the angles of the cams (something as little as 0.03-0.05 % can trigger the noise; -I think I have that in mine)

3) The recommendations for previous similar problems raised by others were linked to either a TSB related to reflashing (update) the ECU, or to a faulty TCM. I'm sure keving can chime in better on the subject.

 

Mine sounds like a POS when it starts. It takes time for the oil to reach the heads and shut it up. Total BS form such a nice car. They probably strung that engineer up by now. Never heard a ricer do that, not even a Ford drives me nuts.

The Trany problem could be the TCM have the codes pulled see what turns up. Sounds that way because it went away when you restarted.

If the droaning turns of when a/c turns off that could be a good thing. See if it does it with the fan on with no A/C if so I would have a look at the blower. A/C systems screw up everything when they turn on.

 

2)If you have a 3.0L engine, engine chatter is normal upon cold start. Its a design flaw where the oil drains out of the four cam tensioners after a while and it takes a second to build the pressure back up in them. The thinner the oil you use, the faster the noise will go away.
Now if you have a 2.8,2.7, or 4.2L, then something is wrong and needs to be checked out as chefro said.
3) could be TSB related, but it sounds like you have a bad TR (transmission range) switch. There are little magnets that read the contact when selecting gears, the magnets fall out or get stuck, so it goes into limp mode. To cure that you change out the TR switch. Check TSB's first though. A fault code will be stored if it has a bad TR switch.

 

0w-40 is your friend. Prolly need a good oil system cleaning too.

1) does the noise go away above and below 1500 rpm? Prolly a loose (ish) bracket.

 

Sorry, it's a 2002 A6 quattro w/ 3.0 - 59k miles

I'm using Amsoil 5w40. As for an oil cleaning, I ran SeaFoam for 40 miles and drained the oil as soon as I got home - almost got 3rd degree burns from that!! I'm going to run the Amsoil for a few thousand and do another change before I go to the yearly / 10k mile intervals. I also sent off a sample (old oil prior to seafoam) to Blackstone Labs, so I'm interested to see what that turns up.

Yes, it is the 3.0. The sound sucks b/c out of 19 vehicles I've had - it's the only car that's ever done it and also the nicest car - not a good mix IMHO. If you guys say it's "normal" though and not causing extensive wear, then I'll deal w/ it - it's only a second.

The A/C issue is only at 1500. I can faintly hear it around 1300-1700, but it peaks at 1500 and it definitely seems mechanical - not a blower b/c that would be steady wouldn't it? (I mean, the fan is always spinning the same speed at all rpm ranges b/c it's electric). Anyway, I can actually feel a slight vibration through the steering wheel due to this noise - that's how bad it is.

So, this car can throw codes and not cause a light to turn on? What kind of engineering is that? How are you to know something is wrong - when it just stops moving? I guess I'll order a Vag-com and see what's up.

AudiTech79 - that's what it seemed like to me too. I've dealt w/ this same issue on my Jeep before w/ their NSS (neutral safety switch), but the isue resolved itself after a restart, so maybe it is a computer issue?!?

Aren't the computers on these things ridiculously expensive? Also, where is a good place to get replacement parts if it turns out I need a TR, or valley drain plugs, etc?

Oh, one other thing. When I was changing the oil, I noticed a motor bracket at the front of the motor and the bushing was so bad, when I touched it, it crumbled. Needless to say, I stopped touching it, but I guess I need a new one of those too - or at least the bushing. Hmm. Maybe that could cause my noise? Bad vibration at 1500 that harmonizes through the body?!? Maybe there are several bad bushings on motor mounts? Is this common too?

Thanks to all!!!!

 

There's another thread about shake at idle; supposedly bad bushings in the motor mount causing a bad shake at idle.
Well, in my opinion if the engine mounts are bad, the car should shake or vibrate constantly, not only at idle. It's only logical...
I think the Non-retention valves in the valley pan are 078 103 175D. I don't remember where exactly I came across it (ECSTuning or GenuineVWAudiparts.com) and they are about $ 48/piece. - that's in case it turns out those are causing the noise.

As far as the blower motor, mine did it right when I purchased the car, in my way back home and I got "scared" for a little bit. "Wtf is wrong with the car? I just bought it"
Well, is coming and going and so far I didn't do anything about it; so no, it shouldn't do it necessarily all the time, or constantly. And by the way, it isn't about the blower (the plastic fan), but about its motor.
Anyway, you say you can feel vibration through the steering wheel from the noise. Well, that may be something else. Have you checked the tighteness of your drive belt?
Did you have someone getting the rpms at 1500 while you are outside leaning over the engine bay to notice where the noise occurs? Maybe is your AC Compressor or its pulley.

 

There is nothing to wear, the only thing thats chattering are the tensioners. I have never replaced a 3.0L tensioner, so i think you are in the clear. We did extensive testing with oil pressure gauges hooked up and what not (because the engines would do it right from the factory) and found that sufficient oil pressure was built in the motor in less than 1 second so the rest of the motor was getting oil just fine. If you did a seafoam then i would say don't worry about it, unless they chatter for a longer period of time when you start it.

As for the TR switch, its a dealer only part. Its more likely the problem VS the TCM. Although once you get your hands on a vag com we can diagnose it in seconds.

The motor mount in front of the engine is called the snub mount, it basically holds the motor in place for longitiude movement when you step on the gas. If the bushings gets toasted then you can replace just that one bushing mount, they even have upgraded poly eurathane replacements. As for the two main motor mounts, they are hydraulic mounts, so unless you see RED fluid leaking from them then they are ok. When they leak it kinda looks like dried up blood on the bottom of the mounts. A bad snub mount could cause more of a bang when you accellerate, but it could cause a metallic noise if the bushing is worn to the point where its hitting the brace instead of pushing on the bushing.

 

Thanks for the help and reassurance. I've never given a second thought on buying a used car before, but being this is my first Audi and things tend to be more expensive, it causes me excess worry.

My Vag-Com will be in tomorrow, so after work I plan on playing around w/ it. I have no idea what I'm doing though, so if anyone (hint, hint Auditech79) wants to chime in w/ what to check out to diagnose this tranny mishap (so far still an isolated incident - fine all day today) please do.

 

Lots of folks on this forum know how to use a vag com, if there is something you can't figure out and im not available or anyone isn't helping you PM myself, or Jackmup. I know for a fact that his skills with the vag com are advancing at a very fast rate.