Jerking

[James123]

My a6 jerks when I accelerate hard  after first gear if I slowly build up speed it's fine can any one help me please 

[Trevor]

Hi James

Could be a worn patch on the Throttle Potentiometer or fault in the Air Mass Meter....vacuum leak, etc

I would run a scan on the ECU to see if there are fault codes present and go from there

Let us know what you find

Cheers  Trevor

[James123]

I've had the egr valve blanked and had a new air mass sensor as light came on dash and computer showed these faults now it boosts fine just jerks when floor it also have abit of smoke when I do 

thanks 

also I have checked my service book and fuel filter has not been done since 92000 I'm now on 147000 could this have any thing to do with problem 

[Brad-B5]

Hi James

10 hours ago, James123 said:

fuel filter has not been done since 92000 I'm now on 147000

This could be apart of the issue, change it and see if it makes a difference, if so keep us updated on the issue would be interesting to see what the issue of the problem was.

Kind regards

Bradley

[James123]

Changed fuel filter drives nice now apart from I'm getting a lot of black smoke when I boost 

[Brad-B5]

Great, it just need's to filter though over abit of time, do a few high revs and take it on the motor way and hopfully will clean it self out :)

[Magnet]

Hello James,

Glad your issue is sort of fixed. You don't tell us whether your car is petrol or diesel - it would be a help to know- although I am suspecting diesel. As far as I can gather Audi do not, or at latest did not, have a specified mileage/time recommendation for changing fuel filters on their petrol cars. Things may have changed in very recent times, and I would be surprised if this ever applied to Diesel engined cars. However,  I would agree with Bradley when he says a fuel filter change was reasonably overdue, but it may be useful to know that the family owned from new petrol A3 did not see a fuel filter change until 100K with no ill effects. Not overlooked, but assumed it had been changed during the main dealer-only servicing. Not so!

Surely VAG must have an interval for diesels - we hope. Back to petrol and fuel filter changes, we had a Volvo C70 2 litre convertible a few years back and that was the most lethargic vehicle ever owned. Armchair comfort - and performance!. Again full main dealer service history and only 58k miles at the time. Changed the fiuel filter as a policy change and it actually noticeable picked its skirt up a bit, not much but very noticeable. This was the only experience until then of a fuel filter actually affecting performance - apart from yours. 

Let us know whether yours is petrol or diesel James.

Kind regards

Gareth.

 

[James123]

sorry it's diesal 

[Magnet]

Thanks James, it makes sense.

Black smoke can be a number of things from the EGR valve (blanked in your case so not that) through to injectors and the simplest of all - air filter issues. In effect, you are injecting too much diesel in relation to the volume of air intake. 

Now it seems you have possibly improved the diesel flow via. a new fuel filter, but how about the air flow via. a new air filter? If it were mine, I would go for the simple option and change it anyway, on the basis that it sets the base line for when to change it again.

What make fuel filter did you fit as a matter of interest, and what make air filter are you going to use if you are going to change it? 

Let's hope this will solve it, but if not, you might just be into getting the injectors bench tested, so fingers crossed. Change the air filter and follow Bradley's advice of giving it an Italian Tune, mind it doesn't sound as if it needs it, by your reference to flooring it! I'm set In my ways, but flooring it is a bit like waking you up in the morning, and getting you to run a marathon! OK James, only joking and perhaps enjoy it when you can, because your driving will end up with enjoyment in pace-with-grace. 

Let us know how you get on.

Kind regards,

Gareth.

p.s. Can someone enlighten us on VAG's service intervals for fuel filters on diesel engines? 

[Trevor]

Fuel filter replacement is usually around 35-40k miles although I would do a change at the lower figure if you love your car/engine.

Quality of fuel filter is imperative when choosing a replacement and it is probably the only time where I would go for a genuine OE part as there are so many inferior after-market filters out there that can cause tremendous problems with engine running on the modern HDi fuel systems.

[Marc Pizzuto]

Just purchased a 2021 Audi A6.  It was a former loaner car with just over 8,000 miles. Only problem I see at this time is rough  jerking or lurching upon hard acceleration from a dead stop. Ie. trying to pull onto a very busy highway from a side street or parking lot with cars already traveling over 50 mph.  If I accelerate slower there's no jerking but chances are I could get rear ended for not getting enough speed up quickly enough.  I've seen mostly explanations there is something wrong with the fuel/air mixture or transmission problems but the dealer had a different explanation.  That is: if car accelerates to quickly the CVT transmission is trying to find the right gear and has trouble keeping up.  Just doesn't sound right to me.  Does anyone have any thoughts?