A6 tdi 2,0 2007 vibration. Timing issue?

[edfl]

Hi! I have a 2007 A6 TDI 2.0, manual, 90.000 miles with perfect service record, no error codes and no noises from the engine. However, when standing still in neutral at temperature, theres an irregular judder/wobble at 1200 rpm which turn into a constant regular shaking when it reaches 1600. After 2000 rpm it goes away. The judder at 1200 is non existent at cold start. The shaking at 1600 also faint when cold. There is also a noise when driving and pressing down the clutch, like something scraping that's winding down.

Last week a non Audi shop said it was the DMF so I had that and the clutch replaced. However, fun surprise, the shaking and the noise was exactly the same. Day after that the regular service was done at Audi and the car seems ok except for the shaking. (Should mention that the DMF was in fact bad but not the cause of the symptoms.)

Visited the shop that fitted the DMF today again and had them check the timing. The cam belt was replaced last year so I was hoping maybe they botched it a bit. The engine is smooth at idle and also above 2000 rpm.

At idle it read +8,16 on the intake (torsion value) and went down to 1,53 at 2800 rpm. The exhaust was -2,94 constant at all rpm.

My question is: what values should it read and could this be the cause of all my problems?

Thanks!

PS
Later edit here, the torsion value was -2,94 the 8,16 was injection duration.

[Novica]

I remember that on PD engine (1.9 tdi, AVF code was mine, with 8 valves only) you can check timing with VCDS. You go in engine address 01, select measuring blocks, select channel 004 and in field No. 4 you should see timing. It should be 0.0 degrees, tolerance value should be between +3.0 to -3.0 (but I think that 0.0 should be if they have made timing belt correctly, mine was always 0.0 as I did timing belt service). Reading must be done when engine is at operating temperature and on idle (coolant temp above 80 degrees). There should not be fluctuations more then 0.5 degrees (steady is preferable), if there is fluctuations more then 0.5 it means that belt is loose or tensioner is loose or not good. If your reading are out of range (+3.0 to -3.0) then you have to readjust timing for sure. But I am not sure if timing issue can be cause of this vibration.

[edfl]

Thank you for the reply! That is really good to know. As I said mine was at +8.16 (at 90C and idle) however at idle it did fluctuate constantly between 7.65 and 8.16. The exhaust was at -2,94 constantly through any rpm. Still the engine runs smooth on idle.

[Novica]

I think it is too much out of range, should be adjusted. I do not know will it cure the issue but if I am in your shoes (regardless this issue) I will adjust the engine again. They can try adjusting without putting it in service position (removing bumper and other stuff) moving the hub of each camshaft but I am afraid that they have to do all over again (locking the crankshaft with special tool and adjusting both camshaft).

[edfl]

Thanks! It is at least a good start I think. And an easy one, the adjustment. Quite pleased to have discovered this since nobody had a clue to what might be wrong. I had it checked for this problem at a shop a year ago and they couldn't say what it was. Stupidly I chose an independent shop that was closest to where I live and all these thrust values seem to be some sort of state secret. Talked to three Audi shops today and none of them could or would say what the thrust value interval should be. But I was welcome to book a diagnostic check.

I'm not too keen on paying for another check right now after the DMF and clutch expense. But the timing is at least something to go on so I'm cautiously optimistic.

[JoeAudi16]

Hi, did you get your issue sorted out? I have exactly the same issue. Even the readings are the same (8.16 and 7.65) apart from minus value which mine is -0.89
My engine shakes at 1300 and 1800 RPMs and goes away when over 2000 RPMs.
Also had my DMF changed although I have got multitronic gearbox (cvt).

[edfl]

The mechanics that fitted the new DMF and clutch are right now working to set the belt correctly. However Audi says that the injectors should be set as well after timing belt change and that is something I think only an Audi shop can do properly. In retrospect it would have been better to go to Audi directly since there is little knowledge out there about what all the correct values should be for different items. If this won't help there's the EGR valve that's the next likely suspect.

How does your drive otherwise? The Audi mechanic that looked at mine and drove it thought it was a bit weak on acceleration, as if it wasn't getting enough fuel.

Will post back in a few hours and update on the situation.

[JoeAudi16]

Hi, mine doesn't run very well neither. It only goes well around 2000 RPMs. I changed the fuel filter, but no change there. I will blank the EGR for a while, clean the intake manifold if needed and if that won't help, I will most likely take it to Audi dealer, let them to check all measurements coz I'm fed up of garages telling me that thay don't know what the right measurements should be. Not even audi independent specialist know.

[edfl]

The car is back, runs possibly a bit worse now with the timing belt set properly with pins. It was just half a cog on the intake that was off. The values are the same though, so something else is wrong and the indie mechanics are clueless.

The thing is I fiddled a bit with the belt myself this weekend, very carefully but it's still a bit foolish. However, I did manage to get rid of the shaking at 1200/1300 completely and the car ran well. It started first at 1500 after that. That's why I was hopeful that a proper correction might do the trick. It didn't, now the shaking is back at 1200 also.

But since it made a difference when I did it and the values are still off after the adjustment I bet there's something above the head that's causing this.

Another weird thing it does when starting cold and revving up to drive off is that sometimes the revs jump down for a millisecond and back up again even though the accelerator is in the same position. Just a few times, only after start. Anything like that on yours?

[JoeAudi16]

Oh that's not good. I've been in two garages today and when I told them about timing belt values they didn't even know them, not even independent audi specialist garage. My car run quite ok in the morning when engine is cold apart from today when it wasn't that cold outside. This afternoon around 15:00 car was really struggling, outside temperature was 21 degrees. Basically it runs better when cold. Yes mine loosing revs sometimes as well, but only tiny bit. Mine also doesn't ever have the same starts, I mean sound of the engine. Sometimes start up like nothing and sometimes makes very weird noise. I phoned up audi garage today and booked my car for diagnostics for next monday. It will cost me £60 but they at least know the values for measurements. I expressed that I want them to check timing belt and injectors as car isn't running well. They said that they will check it. I'm leaving car there until they find the problem no matter how much it gonna cost coz I'm fed up now. I'll let you know results. Befor that I will take off air intake manifold and EGR valve and see if they are not clothed.