Goes flat in 5th gear....

[NotNormal]

The car :

Audi A6 3.0 TDi Auto Quattro 2009 facelift
CDYA engine code

The problem :

Hold a constant 2/3 's throttle - run through the gears without deviation - 1,2,3,4 all pull strong, smoothly drops into 5th and goes flat, still accelerates, then pulls strongly again in 6th

The fuel econ is also poor, 25mpg to the tank (long range 80L tank) - mpg measure correctly from fill up to fill up.

The parts it's had recently :

Complete fuel system : hpfp, lpfp, regulator, injectors x6, rails x2, link pipes, vacuum pipes, filter, filter housing, relays, entire wiring and ECU check, tank swabbed out, front to rear fuel lines flushed out, software update, adaption values reset (fully adapted again now)

Complete auto box rebuild - new oil, new transfer box oil, new rear diff oil

Turbo inlet seal replaced

Swirl flap updated and new rods fitted (both banks) (full adaption since this also)

The car has no fault codes sorted, non pending


All the work work has been carried out at main dealer Audi


Anyone got any ideas ..... We are stumped .....

 

[a6_chris]

If you haven't already done so, get rid of it while its still working.

obviously must've been a Friday afternoon car!

 

[Nino76]

Hi NotNormal,

Are you sure it's not just how the car is intended to pull? I have the same model and also thought its a bit flat in 5th but I just put it down to the size of the car and the gear ratio not being as tall. Has a dealer/audi actually acknowledged it's a "problem"?

Anyone else here to comment on how 5th gear should pull? Should it be strong on a 3.0 tdi Quattro?

Cheers,
Nino

 

[NotNormal]

Hi Niño76,

Deffo not the way it should be as once the rpms reach the right speed to select 6th you can feel it push you back in your seat again

Checked it on my firmed v-box too - it went considerably flatter in 5th compared to the results in 4th and 6th, if he stil has the data file I'll post the picture

Yes, dealer has adnolleged the problem

 

[Nino76]

Hi mate,
Im more than happy to compare notes on what my car does just in case what your experiencing is just how the car is.
Going from an audi S4 I've noticed a difference due to my A6 being a diesel i.e the normal rev/boost range compared plus it was lighter and bi-turbo and remapped.
I do definitely note the a6 doesn't pull hard in 5th compared to 1,2,3,4 but if you use manual and go higher in 4th then change to 5th it does pull much more. Its difficult to explain but assuming my car is fine i have found dropping from 6th to fifth doesn't give u a kick of power compared to if i was in 5th dropping to 4th.

Apologies if this doesn't make sense or applicable to your issue but just trying to give my opinion that it might just be how these cars are.

When you say 'flat'. Do you mean nothing there at all?

I have some good contacts at Preston Audi. I'm more than happy to ask about it for you.

Nino/Nigel

 

[NotNormal]

That does sound quite similar - but I've tried 4 other cars now and they don't suffer / show the same characteristics

It's not as detectable in 'D' but in 'S' and manual modes it's noticeable ..... 98% of the time
On the odd occasion that it doesn't go flat it pulls strong and feels great .... But sadly this rarely happens

By going flag, I mean that the car still accelerates but if it were a petrol it would be like the map has had all the ignition pulled out of it.
That's keeping a constant throttle
It's kinda like its sat on a torque limiter and the ecu is holding it back

I've check the gear ratios and spoken to friends in various forms of the automotive industry and Motorsport and they concur that the gearing ratios shouldn't give the flatness I experience

Once it's climbed through 5th and drops into 6th it pushes you back in the seat like 4th gear does

Personally - I think it's a software issue
I need to check the revision of the firmware on both the gearbox ecu and the engine ecu the see what the level is like compare to what Audi Germany have issued
Having said this, even if my cars is running the latest level I think when it was last updated I may have had a curry put line of code or glitch in the download from Germany causing this


Tom