I want to sort this once and for all.

[Bandycoot]

Since October I have been getting a constant problem. The ABS, traction control and EPC lights have been coming on and no matter what I try I cannot cure the problem. The ABS and traction lights are bad enough but when the EPC light comes on then I only get very limited throttle response and sometimes the car will not accelerate at all. So far I have done the following:

Replaced MAF.
Replaced both rubber elbows on air intake between MAF and throttle body.
Replaced Throttle body
Replaced ABS ECU
Replaced one pre-cat lambda probe
Just replaced throttle pedal position sensor (two days ago)
Had two of the bolt holes for the throttle body on the inlet manifold helicoiled (sort of) but I think the machine shop made this worse and have created an air leak.

At the moment all three light come on straight away or very soon after starting the engine. With the EPC light on then the car is almost un-drivable. I can remove the EPC light by stopping the car and turning the engine off then on again, but it will only come back on gain shortly afterwards. However, after I have driven the car and it is well up to temperature, if I stop and leave the car for a short while the lights will not come on and I can drive normally. I have only been driving it very short distances at the moment as I don't need the car for work and can't trust it to get me there anyway.

This is what the latest VCDS scan has found. This was done this morning.

VCID: 78FF100A584730DEA37-5140
1 Fault Found:

17579 - Angle Sensor 2 for Throttle Actuator (G188) Implausible Signal
P1171 - 35-10 - - Intermittent

I also get a fault code from the ABS controller saying to check for fault codes in the engine ECU. When I clear all fault codes and do a throttle body adaption then all three lights go out, but if the engine is cold then they come straight back on again.

I been to see Audi about it and their workshop manager said it was more than likely an air leak triggering things off. Which is getting me thinking; if the lights go out after the engine is hot then maybe the expansion of components could seal any air leak in the system. My thoughts are pointing towards the inlet manifold. Could this leak internally i.e. the flaps? Speaking to an Audi specialist last weekend, he suggested it could.

Anyway, I need help on this one as no matter what I do nothing seems to work.

Thanks chaps

Steve

[Delboy]

Looks like you need to carry out a throttle body adaptation, have a google for it you will find plenty info

[Goran]

And if its not the adaptation, you can always try a smoke test, but you need to pump reasonably dense smoke in there if its a tiny leak.

[Bandycoot]

I have done throttle body adaption after throttle body adaption. I am an expert at doing them now. Doesn't work. I do one then the lights come on straight away if the engine is cold. I've just been out in the car and when I mentioned earlier that it drives normally if the engine is hot, err, no! If I accelerate hard then all three lights come on and little acceleration.

I'm still leaning towards an air leak in the inlet manifold. I've found a machine shop that can hopefully skim the mating surface where the throttle body sits. This is where I feel the leak could be. If it's not the inlet manifold then god knows what it is.

[Goran]

If it was my car I would spend more time diagnosing what could be causing it, rather than taking things apart randomly. You have a throttle actuator fault code, any others?
Starting point would be to examine throttle actuator and try to see the fault, and perhaps try to fix it first. The other faults may be cascading from that single fault and may disappear once its fixed?

[Bandycoot]

Hi Goran

I've been trying to diagnose this problem for months now. I can assure you none of these items have been replaced randomly. I've been seeking advice from people who know more about these things than I do and going from there. If the advice appears sound I will act on if not then I won't. If I'd taken all advice given I would have spent thousands and probably ended up no better off.

I understand something is triggering the fault code and this is what I'm trying to establish. I sometimes do get other codes namely for both throttle valves. I sometimes get a MAF fault code, which is odd as this is a new one.

The trouble is I am sometimes getting conflicting information. Some people say both throttle valves are in the throttle body some have said one in in there the other is actually the throttle position sensor. I was assured this was the problem which is why a changed it recently. I've been told by Audi the throttle actuator is in the throttle body but is this the case?

The current direction I'm looking is to look at the inlet manifold. I've seen two Audi specialists recently and they have both said this is a strong possibility.

If you can spread more light on this I'd be very grateful.

Thanks

Steve

[Goran]

It sounds like a tricky problem which I dont know much about.
If you already put on a new throttle body and still get the throttle error, that's very strange. Have you got ElsaWin? best 1st course of action is to follow the diagnostic steps as per Audi workshop manual.
I would have thought it would be easier/cheaper to do a smoke test of the whole intake system for leaks before removing and dismantling things? Your local mechanics surely know how to do this quick test?

http://www.youtube.com/watch?v=FfiQ7qWiG-M

here is the ElsaWin procedure for checking throttle valve sensors.

[Bandycoot]

Hi Goran

Thanks for the information.

To be honest it's not a new throttle body but a second hand unit from A8 Parts. However, it's funny I'm getting the same fault codes.

To be honest yet again I didn't know about smoke tests. Nobody over here has mentioned it. Now that I know I'll see if anyone has a smoke machine or make one myself. It could be academic now as the manifold is in pieces with one half with a machine shop to try and repair some bodging another machine shop did. Hopefully this will sort it.

As for ElsaWin, no I don't have it. I have been trying to use Bentley but that doesn't work on Windows 8, although someone did send me some information on how to get it to work, I have yet to do something about it. What exactly is ElsaWin anyway and where do I get it?

[Goran]

I didn't realise the manifold was already apart. Good luck I hope that fixes it.
I only found out about smoke tests recently too, but looks like now you wont need one.
ElsaWin is the Audi official maintenance manual used by the dealer, we aren't supposed to have access to it, but like all other software some smart guys cracked it and it is available on ebay. Audi has released a paid access to the dealer manual online for a subscription fee (for example 5 euros buys 1 hour access). This system is called Erwin
https://erwin.audi.com/erwin/showHom...902DD35BD483AA

ElsaWin is simply a hard copy of this, cracked and sold by lots of places on ebay and on the web. I got mine from ebay and its still working fine. I did have to cross reference it once with Erwin on the web, but it turned out to be identical so I wasted 5 euros.
Bentley appears to be a poorer copy of ElsaWin/Erwin for USA, I never used it but I vaguely remember some people couldn't find certain procedures.

[Bandycoot]

Thanks for that. I'll have a look on ebay.