Diesel Sound, Rough Idle In Park Only, Hissing Sound, Clunk

[Indygunner]

Few questions for you professionals - I'm at my wits end.

Ok, first... its a B6 2005 Audi A4 3.0 Quattro 5-speed Tiptronic Transmission - roughly 66,000 miles. Purchased it this March... since then I've done the timing belt, serp tensioner, water pump, plugs, 4 rotors, 4 pads, oil change (0w40 mobil 1), fuel filter, model specific K&N intake filter (oem box), coolant, brake fluid, transmission fluid/filter/gaskets, front and rear diff gear oil, rear main seal... and I think that's about it.

Absolutely zero fault codes. None.

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Anyway I'm having a few issues and hope you can steer me in the right direction.

1.) When decelerating at low speed (i.e. let off the gas in a parking lot or drive through) the engine sounds like a diesel. tick tick tick tick tick tick. When I give it gas, the tick goes faster until about 1500-2000rpm and then it goes away. When I slow down, the tick comes back and slows with the RPM.

2.) When the car is in park, once it warms up and the RPM goes back down to "normal", the car shakes. Not like an earthquake, but certainly not smooth and very noticeable vs when parked in drive (at a stop light for example). Once I put it in any gear (R, D, TIP, S) it goes away. Granted, in "gear" the idle rpm is higher, but this seems strange.

3.) I just noticed recently (now that it's colder out) that I can hear a hiss/whistle sound from the center/right of the front of my car anytime I accelerate. Most pronounced around 2800-3000RPM, but if I let off, on, off, on it will still do it. Sounds like a turbo or quiet blow off valve almost, and my N/A V6 does not have either. My PCV was just delivered today, going to give that a shot. I didn't order hoses though, so if it's a leak then I'll have to get them. Hoping I can snake it under the intake manifold without removing 1/2 the engine.

4.) Most noticeable after parking, when I go from park to drive, or park/reverse/drive and take off (go forward) the front of my car makes a CLUNK sound - I can feel it in the pedals. Once I'm moving, it doesn't happen again. Was thinking it may be the brake pads, or control arms... but the pads don't show any wear from sliding around (at least externally - haven't taken them apart), and I'm not sure how to test the control arms without just replacing them.

Any ideas, tips, etc. would be greatly appreciated.

Thank you so much!!!

[imnuts]

I think the 3.0 came with 6 gears, regardless of year or transmission type, not 5.

1. Can you narrow down where the ticking noise is coming from? My first thought when you said ticking and sounding like a diesel was bad cams, but in 2005, that shouldn't be an issue.

2. Have you replaced any of the mounts on the car? Check the snub, engine, and transmission mounts, see if they're all still good. If they aren't, replace, if they are, try just loosening and letting them realign themselves, then tightening them back down.

3. Check your vacuum lines too. The vacuum reservoir is in the front on the driver's side, as well as vacuum lines running along the length of the engine from front to back. You may have a slight vacuum leak, but not one big enough to cause any codes.

4. May also be mount related. One of the previously mentioned ones, or the rear diff mount.

Sent from my DROID Turbo 2

[Indygunner]

Thanks for the info!

As far as I know it's referred to as the 5 speed tiptronic transmission (automatic) my 05 is the b6 not the 2005.5 b7. Maybe I'm wrong.

As for the noise got a decent video of it once. Between 3-4 seconds in. Sorry it was dark.

https://youtu.be/igCC7MNvv9w

[Indygunner]

Here's the clunk around 1-2 seconds in

https://youtu.be/DTEPGp6XiPo

[Indygunner]

Pcv dramatically improved idle. Honestly it's probably fixed. However... when I take the gas cap off (which I can still do fairly easily) there is still a good amount of suction. If I cover it with my hand it certainly has suction.

How much is too much? Is there a minimum? Or do I have a leak in a hose somewhere?

Thanks!

[CyberPMG]

The Tiptronic was only a 5 speed. I had a 2002 A4 3.0 Tiptronic. Check the cam chain tensioner for the ticking noise. Likely the culprit. I would also have the cam lobes inspected for any signs of unusual wear.

[Indygunner]

Local Indy shop found a leak between the throttle body and the engine. Going to have them replace the gasket, clean the throttle body a bit, and replace the vacuum lines with new 3.5mm lines while they're there. Hopefully that explains the poor performance and the diesel sound. If it doesn't - I guess the chain tensioner is next on the list. Sigh...

Thanks everyone!

[SJorge3442]

Local Indy shop found a leak between the throttle body and the engine. Going to have them replace the gasket, clean the throttle body a bit, and replace the vacuum lines with new 3.5mm lines while they're there. Hopefully that explains the poor performance and the diesel sound. If it doesn't - I guess the chain tensioner is next on the list. Sigh...

Thanks everyone!

Just so you know, its not really a gasket on the manifold and throttle body, but instead an o-ring seal. Not that it matters. Just figured I'd inform you that their just removing the oring and replacing it with a new one.

[imnuts]

Make sure they don't remove the plate on the throttle body when cleaning it, or you'll need a new one of those as well.

[Indygunner]

Thanks for the info everyone! And for the corrections - my first german car so obviously I need to be more precise in my verbiage vs my chevrolet LOL.

Took it to the indy shop and they did a VAG scan - the throttle body adaptation will not work. The error code (which I didn't think to ask for since they are friends of mine) will not clear. He said most likely the throttle body is dirty and needs to be cleaned, new o-rings, and then do the adaptation. I also picked up the breather hose for under the intake manifold since he'll be right there anyway. Also got new vacuum lines, new check valves, and a few misc clips that I noticed were replaced with zip ties by the PO. Hopefully that does it.

With that said, question... would a dirty unadjusted throttle body make the diesel sound at low rpm when on and off the gas in a parking lot? I'd imagine it's dumping fuel to overcompensate for how lean it is and essentially stalling the engine which is restarted by me moving in gear. Sounds plausible - and would be WAY better than lifters/cams/etc.

I'm waiting on parts, should get them in and get the job done early next week. Will keep you posted.

Thank you!

[Indygunner]

Couple more videos if this helps too.

Clunk: https://www.youtube.com/watch?v=KNcnkOlSMGA

Diesel sound: https://www.youtube.com/watch?v=nga710laX3s

[SJorge3442]

Thanks for the info everyone! And for the corrections - my first german car so obviously I need to be more precise in my verbiage vs my chevrolet LOL.

Took it to the indy shop and they did a VAG scan - the throttle body adaptation will not work. The error code (which I didn't think to ask for since they are friends of mine) will not clear. He said most likely the throttle body is dirty and needs to be cleaned, new o-rings, and then do the adaptation. I also picked up the breather hose for under the intake manifold since he'll be right there anyway. Also got new vacuum lines, new check valves, and a few misc clips that I noticed were replaced with zip ties by the PO. Hopefully that does it.

With that said, question... would a dirty unadjusted throttle body make the diesel sound at low rpm when on and off the gas in a parking lot? I'd imagine it's dumping fuel to overcompensate for how lean it is and essentially stalling the engine which is restarted by me moving in gear. Sounds plausible - and would be WAY better than lifters/cams/etc.

I'm waiting on parts, should get them in and get the job done early next week. Will keep you posted.

Thank you!

When you're revving the car I'm hearing a lot more rotational noise than I hear with my 3.0 It sounds like when you're revving it that the serp or timing belt is too tight. It sounds like a belt hiss(for lack of better word) to me. Regardless, that diesel sound to me sounds like it could be something going on with the exhaust. My resonator recently broke and my car is sounding like a diesel from that.

When they clean the throttle body, like ImNuts said, its important to NOT REMOVE the throttle plate. For whatever reason, once its removed, you need a whole new throttle body. I'm confused as to why the adaptation wouldn't work too. Usually when the throttle body is out of whack it causes a rough idle and sometimes misfires.

[imnuts]

If there is a stored code, I'd get that and see what the cause(s) are and ways to correct.

Sent from my Pixel XL

[Indygunner]

Great idea about the exhaust! They just did my rear main seal - as part of that they cut the exhaust, and used a new piece of pipe/clamps. Maybe that has a small leak..

And got it/thank you for the throttle plate info. Fortunately these guys are more experienced than I'll ever be and wouldn't do that. (Funny enough they were doing this job on a b6 avant when I came by to run codes. Must be the weather... lol

[Indygunner]

Didn't get the code unfortunately - should have - but it was the code saying the throttle body could not adapt. Wouldn't clear. Wouldn't adapt. He believes it is dirty. With the symptoms I'm showing of rough idle and about 14-15mpg I think he's right. Still going to re-do my vac lines and breather tubes.