2.0 tdi poor mpg

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sliced

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hi guys just picked up my new 2011 C6 a6 and it's absolutely fantastic, however the mpg doesn't seem quite right.

50 mile motorway journey on the way back from collecting it, was giving 34mpg at 75mph the whole way.

This doesn't sound right for a 2.0 tdi cvt, any ideas?

I gave it a scan with vcds and nothing showed up, and it's last service from audi was done last month.

Any ideas what it could be? Or is the fuel economy really this bad?
 
Doesn't sound particularly good. Check the tyre pressures, are they original alloys or larger wheels, What kind of rubber does it have, a lot of the Chinese tyres are not that good on rolling resistance.
It may have done a regeneration cycle if it's been running short journeys recently. Fill it up and record a few tanks worth to see how the trip computer compares to real world figures.
How many miles has it done ?

http://www.honestjohn.co.uk/askhj/answer/41414/why-is-my-audi-a6-tdi-s-fuel-economy-so-poor-
 
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Hi they are the original alloys 255 35 19, wrapped in new continental sport contact 5p's. Pressure is fine too on them.

Dpf regen unlikely to be causing low mpg, but will check mpg on a similar length motorway journey today.

Quite baffled by this as I have an A4 2.0 tdi that gives close to 55mpg and had a Passat 2.0 tdi that gave 53.
 
255's and 19's , that's a whole lot of unsprung weight and rolling resistance !
 
Just completed another 40 mile motorway round trip, 32mpg. not good at all. :grumpy:
 
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Comming back to think about it

The car did have a belt change and water pump done on day of collection, so might be something to do with incorrect timing?

Anyway to check this in vcds, step by step help would be much appreciated
 
How is the car performing???

If power feels low then I would look at boost leaks and MAF.


With VCDS, with engine running, go to engine and then select measuring blocks. Click "Go" and click up through until you find what your looking for. Easy.
 
Pyeman said:
How is the car performing???

If power feels low then I would look at boost leaks and MAF.


With VCDS, with engine running, go to engine and then select measuring blocks. Click "Go" and click up through until you find what your looking for. Easy.
Click to expand...

No option for measuring blocks, it's greyed out for CR engines :-(
Car seems to be performing fine, no obvious faults
 
On EDC17 ECU's they use the advanced measuring option. You get a lot of things to measure.
On my 3.0 TDI the cam timing is shown as the synchronous vangle. You just need to find it in the list of measuring values.

Synchronous angle


Usually the sync angle is something like 0 +- 3 degrees .
 
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desertstorm said:
On EDC17 ECU's they use the advanced measuring option. You get a lot of things to measure.
On my 3.0 TDI the cam timing is shown as the synchronous vangle. You just need to find it in the list of measuring values.

View attachment 97701

Usually the sync angle is something like 0 +- 3 degrees .
Click to expand...

Hi thank you very much, just had a quick check and it's showing -0.83 degrees

Is that a cause for concern ?
 
Last edited:
That timing value sounds fine to me. I would try logging the DPF differential pressure sensor readings to see if that is looking OK.
 
desertstorm said:
That timing value sounds fine to me. I would try logging the DPF differential pressure sensor readings to see if that is looking OK.
Click to expand...

Had a look around the DPF readings, all seem fine :weary:
This is really bugging me, tempted to pour some redex or BG244 into the fuel
 
Edit: Turned out to be a split boost hose, replaced and all sorted :)
 
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Glad you found it in the end. So many things that can cause these kind of issues. Surprised you couldn't hear it hissing
 
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