Running issues A6 2.0 TDI Ultra

[Davidacarrick]

I am having running issues on my 2015 Audi a6 2.0 TDI avant 122,000 miles. 190ps ultra. Manual transmission. 
 

Car has been scanned with VCDD no DTC/fault codes or engine management lights.

 

To explain:

 

when I drive in 1st, 2nd and 3rd fully smooth through rev range whether I accelerate slowly or floor it. 4th is a bit intermittent until higher revs 3000+, 5th and 6th I get shaking and vibrating but also feels like it effects power. When I accelerate slowly at half throttle it’s not as bad or prominent but if I floor it in 5th/6th for acceleration anything about 1500 revs it’s a shudder acceleration (not like a flywheel failure) but more like you were going on and off throttle every second until revs increase.

 

recently had wheel bearings changed and drive shafts so not related to that, tyres are new, intake to turbo pipe has been replaced, new air filter and no obvious blockages. MAF sensor showing as measuring correctly with no faults.
 

It’s as if something is struggling (air/fuel) but no fault codes and I can’t get my head around it.

 

any suggestions or advice?

[Stevey Y]

41 minutes ago, Davidacarrick said:

I am having running issues on my 2015 Audi a6 2.0 TDI avant 122,000 miles. 190ps ultra. Manual transmission. 
 

Car has been scanned with VCDD no DTC/fault codes or engine management lights.

 

To explain:

 

when I drive in 1st, 2nd and 3rd fully smooth through rev range whether I accelerate slowly or floor it. 4th is a bit intermittent until higher revs 3000+, 5th and 6th I get shaking and vibrating but also feels like it effects power. When I accelerate slowly at half throttle it’s not as bad or prominent but if I floor it in 5th/6th for acceleration anything about 1500 revs it’s a shudder acceleration (not like a flywheel failure) but more like you were going on and off throttle every second until revs increase.

 

recently had wheel bearings changed and drive shafts so not related to that, tyres are new, intake to turbo pipe has been replaced, new air filter and no obvious blockages. MAF sensor showing as measuring correctly with no faults.
 

It’s as if something is struggling (air/fuel) but no fault codes and I can’t get my head around it.

 

any suggestions or advice?

Hi I would suspect an air leak the other side of the MAF, also check the MAP sensor and the DPF sensor I had the same on my car and ended up changing both MAP and DPF sensors to cure this as the EGR was staying open when and allowing gas recirculation when you were trying to clog it in higher gears when it needs the maximum amount of fresh air, what diagnostic reader are you using as anything other than VCDS/OBD Eleven wont necessarily flag any codes, before I bought new sensors I had already changed the EGR valve which was pretty much mint because of the design it only gets hot exhaust gas and no recycled crankcase gas because that gets fed in further down the stream only to discover it might be a blocked pipe to the MAP/EGR sensors, no blockages so it had to be the sensors, don't ask why because they all communicate with each other and I never found out what wasn't working, took me ages playing chase the ace, all part of the wonderful Ultra technology and a very complex engine management software.

Steve.

[Davidacarrick]

I’m only using VCDS.

 

i have changed the dpf sensors x 2 and the map sensor. Map sensor was changed as it wasn’t showing a correct internal air temperature reading many months ago.

[Davidacarrick]

Also air intake pipe from maf to engine has been changed. This was apparently collapsing under acceleration so changed some time ago 

Edited May 22 by Davidacarrick

[Stevey Y]

23 minutes ago, Davidacarrick said:

Also air intake pipe from maf to engine has been changed. This was apparently collapsing under acceleration so changed some time ago 

The only other thing I can think of is the low pressure EGR valve butterfly is clogged and may be slightly open, they are monitored but wont throw a code unless stuck completely, did you check the pipes were clear before fitting new sensors.

[Davidacarrick]

Changed out the MAP and DPF sensors and cleared pipe work tonight with spares I had so will see what happens if anything. Hopefully haven’t stuck the old MAP on that had the intake temperature sensor issue

[Stevey Y]

20 hours ago, Davidacarrick said:

Changed out the MAP and DPF sensors and cleared pipe work tonight with spares I had so will see what happens if anything. Hopefully haven’t stuck the old MAP on that had the intake temperature sensor issue

Hi the AIT sensor is bolted in to the throttle body and is a different element completely the map sensor wont measure temperature, but you could try taking the AIT sensor out and cleaning it as they do get coated and wont read properly

[Stevey Y]

Hi this is a diagram of the throttle assembly the Air Intake Temp sensor is number 12 

[Davidacarrick]

Steve I was advised that was the charge air temperature sensor but apparently the intake air temperature sensor is integrated into the MAP sensor on the end of the rubber tube. Have other issues too….changed my heater support pump but still getting an error. Runs fine when you test it on output tests but think it’s something else locking it up….when you look at the data intake air temperature on one is showing 44C!

[Stevey Y]

22 hours ago, Davidacarrick said:

Steve I was advised that was the charge air temperature sensor but apparently the intake air temperature sensor is integrated into the MAP sensor on the end of the rubber tube. Have other issues too….changed my heater support pump but still getting an error. Runs fine when you test it on output tests but think it’s something else locking it up….when you look at the data intake air temperature on one is showing 44C!

Hi the MAP sensor has no facilities to measure air temperature as it is the same as the DPF sensors it measures barometric pressures, the two air temperature readings come from the MAF and the Air charge temp sensor, these compare the air temperature going in, the MAF, and the temperature of the air going in to the manifold  as the compressed air from the turbo is somewhat hotter than the air going into the MAF between the two they work out what is acceptable within the boundaries of its strategy limits, as for the pump is it the aluminium one to the R/H side of the engine bay, if you could post a picture that would be helpful, only one other question when you replaced the MAF was it an oe Bosch unit as I tried two much cheaper aftermarket MAFs and both failed in short order, ended up buying Bosch again and that cured my problems.

Steve.

[Davidacarrick]

Maf was bought from TPS/Audi and is genuine part. The heater support pump I changed originally was the smaller plastic one at the rear of the engine but going to change the pump that’s at front end of the engine bay under the coolant tank, passenger side.

 

replacing the 645 relay tomorrow under the ECU 

[Stevey Y]

3 minutes ago, Davidacarrick said:

Maf was bought from TPS/Audi and is genuine part. The heater support pump I changed originally was the smaller plastic one at the rear of the engine but going to change the pump that’s at front end of the engine bay under the coolant tank, passenger side.

 

replacing the 645 relay tomorrow under the ECU 

Hi I would leave the pump at the front that is an auxiliary pump that only works in excessively hot weather when the vehicle is stopped it pumps coolant around the circuit to stop the red hot coolant from cooking the cylinder head, worst ways just clean its connections with contact cleaner.

[Davidacarrick]

I don’t understand why im still getting the fault when the smaller plastic one by the engine has been changed with genuine Audi part

[Davidacarrick]

Full coolant changed at the same time 

[Davidacarrick]

I actually can’t wait to get rid of this car next month. It’s been a disaster since I bought it: the list of faults and issues I’ve had with it you would not believe 

[Davidacarrick]

Is there a fuse for the intake air temperature sensor and MAF if so where is it?

[Stevey Y]

20 hours ago, Davidacarrick said:

I don’t understand why im still getting the fault when the smaller plastic one by the engine has been changed with genuine Audi part

Hi I had the same a couple of years ago with four clutch master cylinders all failing within a couple of months, finally bought a genuine LUK unit from ECP and that cured it, I think in an effort to make money they have been buying cheaper elsewhere to bump up profits, I don't blame you for getting rid, I was heartbroken when my one terminated itself back in January when the electronic handbrake let go and it rolled into a brick wall, l have now bought a VW Passat nice and simple as it doesn't throw up a light for every event, brilliant on diesel and adblu the bonus being any new quality branded parts are about a third of the price, example Brembo pads and rear discs £105 the set, the Audi was over £200 for the discs and another £70 for the pads, done 10k since beginning of Feb and then Passat has not missed a beat.

Steve.

 

[Stevey Y]

19 minutes ago, Davidacarrick said:

Is there a fuse for the intake air temperature sensor and MAF if so where is it?

Hi don't think there is one as both items report back to the ECU with pulse signals, with regard to the pump you fitted [not that I ever changed one] is there anything on VCDS for adapting the new unit?, from the rest of your posts I would lean toward the MAF failing again, have you tried re adapting the MAF.

[Davidacarrick]

Have readapted maf as if it was newly installed. Nothing on vcds to adapt heater pump, can only run output tests or bleed cooling and low temperature cooling circuit 

[Stevey Y]

13 minutes ago, Davidacarrick said:

Have readapted maf as if it was newly installed. Nothing on vcds to adapt heater pump, can only run output tests or bleed cooling and low temperature cooling circuit 

Hi might be worth bleeding the circuit as any air in the system will cause it to stop pumping as it registers pressure when it is working and will go to default [stop when no pressure is sensed], if you get the same temperature fault back on the MAF its knackered.

Steve.

[Davidacarrick]

Have tried doing both bleeds on vcds. Car hot, ac off, interior temperature full, fans lowest setting and on an incline but no difference 

[Stevey Y]

24 minutes ago, Davidacarrick said:

Have tried doing both bleeds on vcds. Car hot, ac off, interior temperature full, fans lowest setting and on an incline but no difference 

Hi not wishing to appear stupid but is the pump the right way round as it should have a flow arrow on it.

Steve.

[Davidacarrick]

I believe so….was done for me by a qualified engineer / mechanic and it’s sporadic when it comes up. Will clear then reappears. Sometime with engine management lights, sometimes without 

[Stevey Y]

6 minutes ago, Davidacarrick said:

I believe so….was done for me by a qualified engineer / mechanic and it’s sporadic when it comes up. Will clear then reappears. Sometime with engine management lights, sometimes without 

Hi was this what happened with the old unit, only reason I thought of the direction is that if its pumping against the natural flow that would lock it up but when you test it if there is no natural flow the unit will appear to operate as normal.

[Davidacarrick]

So interestingly I had this come on this morning when the engine hadn’t even been started…..

 

0 RPM and 0% formed load value

intake air temperature 44C? Car has been sat overnight and not used in 10 hours and was about 8C outside in Scotland. Temperature sensors have both been changed with genuine new Audi ones at intake and after intercooler.

 

coolant 44c?! Maybe but surely would be lower after sitting all that time.

Outside temperature 16.5C …. Unlikely at 5.40am

i have a feeling something else is throwing up this issue and not the pump itself