Audi a6 2.5 tdi endine judder! Help please ???

**graemer147** · 09-05-2010,05:11 PM

I have recently bought a 2001 2.5tdi A6 and have noticed when driving under light load (just touching pedal) in any gear between 1600rpm and 2200rpm the engine seems to have a slight shudder/judder which can be felt through the whole car. There seems to be no issues with the turbo kicking in and no smoke/ preformance issues However the shaking has started to severely annoy me. I have had the car scanned at a local garage and no faults were stored, It seems fine under hard acceleration but just a relaxing drive causes this judder to occur. I was just wondering if anyone as expierienced this before or if anyone can point me in the right direction. I have had the maf cleaned and it made no difference also when you rev the engine in neutral it seems to be faultless... Please help???????

**JohnHighfield** · 10-05-2010,11:31 PM

Hi graemer147

I have an 03 A6 2.5 TDi Multi & had a similar shudder. It was very minimal & I generally felt it going up the same hill on a daily basis. I was not sure what it was as the car scanned free from errors & this only happened on the odd occassion.

I have however just changed my ATF in my multitronic (multichronic) automatic gearbox which seems to have removed the shudder. I recently bought the car & there is no evidence of this being done before & it should be done every 40K.

Is yours an automatic?

If so do you know what type of gearbox you have. I believe in 2001 they changed from the tiptronic (which was ok) - for 2 wheel drive cars - to the multitrinic which is prone to going wrong. Quattros kept with tiptronics.

Let us know what gearbox you have ads this may be the problem.... although I am no expert!

John C

**graemer147** · 11-05-2010,03:48 PM

Hi, Thanks for the reply, i believe this is very common on the multi boxes but however my car is a 6 speed manual and i am having what seems to be the same problem. It feels like there is a misfire between those certain revs however the car runs perfectly all the way through the rest of the range and also drives perfectly when you hit the accelerator hard. It just seems to be when you are driving with your foot rested on the pedal... Which coincidently is 30mph in 4th a very "popular position". I am wondering if it could be anything to do with needing a service as it is due but i have only just bought it, Maybe the fuel filter or something i dont know. Could this affect the engine???

**mickmcvw** · 12-05-2010,11:24 AM

Have something similar in my '02 2.5TDi 6-speed manual at just over 2000 revs, slight hesitation at one particular engine rev speed. The car has been like this on and off since I got it < 1year ago and it was serviced when I bought it. It's due a service again now so hopefully I'll get to it over the weekend but my concern would be that it's a fuel pump issue which is big money...

**graemer147** · 12-05-2010,11:49 AM

When i rang my local garage which it is booked in at he told me if it was a fuel injector pump problem then it would happen at all rpms and it would have idleing problems etc. When the car is in neutral and i rev it the engine is as smooth as it gets. It just seems that just as the turbo kicks in when driving it i get a sort of shake judder like a misfire as the turbo is coming in!!! Strange but i had a similar problem on a golf pd 130 i used to have only it juddered like mad all way through the range and it was never rectified before the car was sold. I personaly thought it was a faulty pump or injector!! This one however runs so smoothly apart from the little glitch before the turbo. I really hope this is rectified but i thought i would come on here and get some advice and pointers to give to the mechanic. Another thing i need to do is the fuel filter cause the previous owner only did the oil in the last service so it has'nt had a fuel filter for 25,000 miles im hoping that is the issue and it is not anything complicated!! Another thing is i only seem to get 29 mpg round town on the on board computer over a 150 mile reading. Is this about right???

**Padwick** · 12-05-2010,12:08 PM

MAF sensor maybe? They can cause all sorts of problems if they are gone.

I've something similar (flat spot in acceleration) on mine but I've done my fuel filter.

EDIT: If you are changing your filter, then check if you need the handheld vac pump as part of this procedure. I didn't realise this when I was changing mine and must have took around 30,000 miles off the life of the fuel pump getting the car started again.

EDIT2: Sorry, never read the first post properly. It's actually like a shaking you're getting in the car then? I've seen this one once before (was a 1.9 PD A4) and it turned out to be the 4 injectors were gone, 2 of them particularly bad.

**snapdragon** · 12-05-2010,01:12 PM

Have you had a fault code read?
MAFs are usually reliable Hitatchi units on these engines of this age.
Coolant temp sensor may be duff if not already replaced.

**graemer147** · 12-05-2010,02:14 PM

Id first of all like to thank all you guys for trying to help out on this matter. I cleaned the maf with contact cleaner to no effect. When the car was scanned it was scanned with a universal scanner whichthe garage
had, However I have just purchased a cable from ebay and im going to try Vag com and see what that says. The more ammunition i have for the mechanic hopefully the less it will cost in diagnosing the fault.
Would the temp sensor cause this to happen as personally i think that with it being when the turbo is about to kick in it would either be related to something in that area although i dont really have any idea. I wll change the fuel filter and have been told to change it straight and then make sure i have jump leads and help when i start to crank it up as usually it will drain a full battery before it turns over is this correct???

**mickmcvw** · 12-05-2010,02:14 PM

Originally Posted by graemer147

When i rang my local garage which it is booked in at he told me if it was a fuel injector pump problem then it would happen at all rpms and it would have idleing problems etc. When the car is in neutral and i rev it the engine is as smooth as it gets. It just seems that just as the turbo kicks in when driving it i get a sort of shake judder like a misfire as the turbo is coming in!!! Strange but i had a similar problem on a golf pd 130 i used to have only it juddered like mad all way through the range and it was never rectified before the car was sold. I personaly thought it was a faulty pump or injector!! This one however runs so smoothly apart from the little glitch before the turbo. I really hope this is rectified but i thought i would come on here and get some advice and pointers to give to the mechanic. Another thing i need to do is the fuel filter cause the previous owner only did the oil in the last service so it has'nt had a fuel filter for 25,000 miles im hoping that is the issue and it is not anything complicated!! Another thing is i only seem to get 29 mpg round town on the on board computer over a 150 mile reading. Is this about right???

Symptoms sound very like mine alright. If you try hold it at those revs, does it continue to judder? I'd be happy if it wasn't the fuel injection pump given the cost! I'm thinking about changing all the vacuum hoses around the engine bay as maybe a slight leak in one of those could cause some hesitation on the turbo side of things? What I really need is a couple of uninterrupted days off to really 'get to know (!)' the engine like I do on my Transporter and the wife's Passat.

Don't want to hijack your thread but with VagCom/VCDS, is there a way to look at the boost requested and delivered from the turbo? Might be a pointer.

I'm averaging something similar to 30mpg but mine is an allroad Quattro (AKE engine) so would expect it to give worse mpg than a non-quattro model...

**mickmcvw** · 12-05-2010,02:29 PM

Originally Posted by graemer147

Id first of all like to thank all you guys for trying to help out on this matter. I cleaned the maf with contact cleaner to no effect. When the car was scanned it was scanned with a universal scanner whichthe garage
had, However I have just purchased a cable from ebay and im going to try Vag com and see what that says. The more ammunition i have for the mechanic hopefully the less it will cost in diagnosing the fault.
Would the temp sensor cause this to happen as personally i think that with it being when the turbo is about to kick in it would either be related to something in that area although i dont really have any idea. I wll change the fuel filter and have been told to change it straight and then make sure i have jump leads and help when i start to crank it up as usually it will drain a full battery before it turns over is this correct???

I do have a fully licensed version of VCDS and the scan shows up nothing on this unfortunately.

Fill the fuel filter with clean diesel before installing and it should reduce the cranking. However, as Padwick said, a hand vac pump would be a much better idea than cranking until the batter flattens...