I want to sort this once and for all.

[Bandycoot]

I spent the weekend stripping out and rebuilding the inlet manifold. Put it back and I'm still getting the same problems. This is disheartening to say the least. I'm not sure which direction to go now. I'll do another scan and see what we get. I think I may do a smoke test to find out for sure there are no leaks in the inlet system. After that I'm not sure what else to do except seek more advice.

[Goran]

Sorry to hear its still not sorted. Have a go at doing diagnostic of Throttle Actuator and wiring as per Audi strict repair procedure, since the fault is relating to that.
Only other thing I can suggest is (if the car is in the UK) going over to one of the specialists, MRC or Unit 20, I have not come across a problem that they cant solve.

[Bandycoot]

We have success! I have just changed the fuel pressure regulator and bingo! No more lights and it drive like a dream. When I was taking the inlet manifold off the other day I noticed when I disconnected the fuel hose from the regulator to get the fuel rail off there was no pressure and as there was no fuel leaking anywhere I guessed this was the cause of the pressure loss.

I didn't have any idea that this could have been the cause of the problem. Nobody mentioned it at all. Audi were saying all the time it was an air leak which is why I rebuilt the inlet manifold. Anyway, I'm a happy bunny.

[HPsauce]

Originally Posted by Bandycoot

We have success! I have just changed the fuel pressure regulator and bingo!

Out of interest what and where is that?
(Part number, price and source might be useful too)
As noted in another thread I'm getting some erratic throttle responses at times, though no warning lights or error codes.

[Goran]

Originally Posted by Bandycoot

We have success! I have just changed the fuel pressure regulator and bingo! No more lights and it drive like a dream. When I was taking the inlet manifold off the other day I noticed when I disconnected the fuel hose from the regulator to get the fuel rail off there was no pressure and as there was no fuel leaking anywhere I guessed this was the cause of the pressure loss.

I didn't have any idea that this could have been the cause of the problem. Nobody mentioned it at all. Audi were saying all the time it was an air leak which is why I rebuilt the inlet manifold. Anyway, I'm a happy bunny.

Well done! good to hear it was a easy fix. This is definitely one to note down for future reference.
Its rather annoying that Audi in their own maintenance manual don't mention that fault codes on one component (throttle valve in this case) can be caused by a completely different component. I wonder why it didn't show up any injector fault codes considering the fuel pressure was low?

078133534C - its the little bu**er sitting above the fuel rail driver's side, with the little clear plastic pipe attached to it.

[Bandycoot]

Hang on guys. The problem is back again. Took the car out yesterday and to begin with all appeared to be fine. Then I decided to boot the throttle to see what happens and bang - all three lights came on again and acceleration just died away. To say I am ****ed off is to put it mildly. I haven't had chance to scan it to see what fault codes are coming up but I'll have chance later today. Watch this space.

[HPsauce]

Originally Posted by HPsauce

Out of interest what and where is that?

Thanks for the pm Bandycoot, didn't realise it was so obvious and accessible just under the plastic engine cover.
Sorry to hear your problem isn't fixed though.

[Bandycoot]

Right. Here we go! Just been out and the same thing happened again. Once the engine is warm I boot the throttle and all three lights come on straight away and acceleration is none existent. As soon as this happened I stopped and did a scan. This is what I got:

This is what the engine ECU had:

3 Faults Found:

17967 - Throttle Body (J338)
P1559 - 35-10 - Fault in basic settings - Intermittent
17972 - Throttle Actuator (J338)
P1564 - 35-10 - Under-Voltage during Basic Setting - Intermittent
17953 - Throttle Valve Controller
P1545 - 35-10 - Malfunction - Intermittent


I got these fault codes from the brake ECU

Address 03: ABS Brakes Labels: 8D0-907-389.lbl
Control Module Part Number: 4D0 907 389 E
Component and/or Version: ABS/ESP allrad D46
Software Coding: 08397
Work Shop Code: WSC 12345
VCID: 3169ED2EFBBD2196249-5140
2 Faults Found:

18265 - Load Signal
P1857 - 35-10 - Error Message from ECU - Intermittent
18256 - Please check DTC Memory of Engine Controller
P1848 - 35-00 -

Apparently, the faults codes in the engine ECU cause these.

I did a throttle body adaption and this is the readings on completion:

13:48:04 Group 060: Adaptation of Throttle Valve (TV) Controller (Ignition On && Engine Off)
15.2 % TV Sensor 1 0-10 deg
84.0 % TV Sensor 2 80-90 deg
8 Op condition 0 to 8
ADP. O.K. Adapt status RUN/OK/ERROR

To me it looks like sensor number 1 is outside accepted values. What does anybody else think.

I've looked up the fault codes in the Ross Tech Wiki and this is what they say:

17967/P1559/005465 - Throttle Body (J338): Fault in Basic Settings
Possible Symptoms
Not known
Possible Causes
Idle Switch Open or Open Circuit
Throttle Valve sticks and won't close
Speed Impuls from Engine Speed Sensor (G28) recognized
Possible Solutions
Perform Throttle Body Adaptation

So something is obviously causing the throttle body to keep knocking itself out of adaption.

17953/P1545/005445 - Throttle Valve Controller: Malfunction
Possible Symptoms
Increased Idle Speed
Bucking at Load Change
Possible Causes
Throttle Body dirty
Throttle Body Wiring faulty
Throttle Body faulty
Possible Solutions
Clean Throttle Body
Check Throttle Body Wiring
Check Throttle Body
Special Notes
Use Meas. Blocks & Basic Setting for testing
When found in the NAR 2.0l TFSI: (BPY, CCTA and CBFA) check TSB 01-09-04 or 2018652 for a wiring repair at the Throttle Body.
See Throttle Body Alignment (TBA)

The throttle body is clean as a whistle so it's not that. When it says check the throttle body wiring does that me the internal wiring or the wiring connected to it? What do they mean by 'bucking at load change'?

17972/P1564/005476 - Throttle Actuator (J338): Under-Voltage during Basic Setting
Possible Symptoms
Throttle Body Alignment (TBA) unsuccessful
Possible Causes
Battery Voltage too Low
Possible Solutions
Check Battery Voltage
Connect Battery Charger for Throttle Body Alignment (TBA)

I've checked the battery and this appears to be fine.

One thing I have noticed is that the problem does not appear to be as bad since I have changed the fuel pressure regulator. Before the light would come on straight away but now it's only when I boot the throttle.

[Goran]

Damn! sorry to hear that its back.
I guess check the throttle valve wiring for 5V feed as per ElsaWin guide, and check wiring for correct resistance. Looks like there is another page for testing the throttle valve I will try to find and attach it tonight.
If wiring is all good you could ask A8 parts to ship you a used throttle body assembly, I'm sure its cheap.

[Bandycoot]

Goran. Thanks for that. Any information gratefully received. I had A8 parts ship me out a throttle body a few months ago and the same problems were occurring. Then the potentiometer on that one failed so I stuck the original one back on.

Considering things have improved significantly since I replaced the fuel pressure regulator this could be pointing to a fuel management related issue. I'm going to get the fuel system pressure tested and see what we get and give the air system a smoke test to be sure all air leaks have been sorted.

I understand there is a way of using the measuring blocks and basic settings on VCDS to check the throttle body. Any idea how?