Loss of Power :/
 

Guys,

Having some trouble here, and I'm at a loss for what to do...

2008, A8 Sport, 3.0 TDI..., 100k+ miles

Car was driving fine couple days ago, pulled into the drive and switched off.

Went to go out at night and there was just no power. It accelerated and changed gears fine, but just no "oomph". Took it back home and thought I'd let it sit for the night... wasn't in limp mode and went up through the gears to 6th fine and smooth.

Anyway, this morning, wake up to go to the office - and same issue... just no power at all. Super slow to accelerate up to speed, definitely no torque.

Went to the garage, plugged it in, said the turbo is fine, the gearbox is fine and though the engine had some fault codes it was nothing that should give these symptoms. (Codes: 13128, 06256, 12597)

So we considered a blocked DPF... so I bought Forte diesel cleaner, popped that in the tank and went to go and run it on a long run. This is where it gets interesting...

Car gets up to temperature fine, but when on the motorway the temperature gauge comes down from the middle to the first quarter line, and sometimes even below (towards the cold end of the spectrum).

I pull over worried what might cause this, also considering that I was trying to put it into a low gear to keep the revs high and raise the temperature. On local roads, the temperature went back to the middle. But get back on the motorway for the return leg, and the temperature starts to go down again! And on the return leg I didn't even shift down gears incase that was the problem.

What on earth is happening!?

Suffice to say, I still have no power so perhaps the DPF cleaner didn't work, or wasn't really the problem, I have no idea.

Cruise control also won't lock on.

Final note, before all of this ever occurred, as most diesels - under heavy acceleration it used to black smoke a bit. But now, even under heavy acceleration there's no black smoke, not even any white smoke as I expected from the DPF cleaner.

Anyone had this, or any ideas based on what I've described? Your help would be invaluable.

I'm based in Birmingham in case anyone is about wants to try and help assess what's happening here.

Possibly injector issues? Have you scanned the car fully with VAGcom to see what fault codes come up?

Definitely feels like turbo not kicking in, engine seems fine to be honest.

I don't have VAGcom, but the garage had their own computer system and the three fault codes presented were in the first post but I think I didn't really make it clear... anyway they are:

13128
06256
12597

Does any of the things I mention ring any bells to you?

Also worth noting, I have no fluctuations of revs or anything like that. Stable 900 rpm at idle and steady while driving too.

Hmm none of those codes come up on the ross tech wiki

http://wiki.ross-tech.com/wiki/index...01273#mw-pages

I don't know what to suggest, pretty sure those were the ones displayed on his screen as I scrambled to jot them down on my phone!

What about the symptoms I'm describing, does that provoke any ideas?

13128- turbocharger electrical control
06256- engine mount
12597- intake manifold

Engine mount is not much of a problem but other 2 need to be investigated.

Turbo actuator stuck?
Throttle position sensor?
Fuel filter choked?
Fuel pump(s)?
Air filter?
Intercooler pipes?

Thanks, are these two likely to cause the loss of power I'm describing? As well as this curious issue with the engine temperature?

So I assume that's a list of things that can cause the loss of power, but what about all the rest of the symptoms or the nice list of fault codes that ainarssems kindly decoded? Which of those would correlate?

I must admit when it comes to these electrical gremlins, I'm at a loss for what to do - terrifically complicated cars these A8s!

It's a list of what you could easily check without throwing a lot of money at the problem. You really need to get the car plugged into VCDS and have a scan done so that you can pinpoint the fault. Generic OBD code readers don't give enough information

I understand. Is there anyone near Birmingham with VCDS?

My garage has just his OBD system :(

List of owners/forum members with Vagcom cables is here -
http://forum.a8parts.co.uk/showpost....9&postcount=79

Thanks, I dropped Singh a message, as he is the nearest person to me.

Presumably the easiest to diagnose would be the turbo issues.

Can you recommend any other thing to look for in terms of symptoms? Can we be 100% sure it's not the DPF at this point?

And finally, what about the movement in temperature at motorway speeds...

Just a note to say thanks guys for all your input, I really appreciate the community help!

Just a side note - not sure if its an update or more of an observation.

Checked all the fuses, all were okay (on both sides).

However, I lifted the bonnet and powered off the car, and noticed a clicking noise. Almost like an open/shut valve of some kind. It went on and off about 3 or 4 times, then closed.

I don't know what it is or if it was there before, but then even when I turn the ignition on, and not the engine, then switch it off - the same clicking noise is present.

It's similar to this:

https://www.youtube.com/watch?v=rDG3...ature=youtu.be

The engine being so loud, I don't know if its doing it while in operation, but it's definitely doing it when I switch everything off. Is this normal behaviour or could it be a signal?

Scan tool image attached

Turbo sounds likely. Best thing to do is clear the codes and see if they come back as the machine on the photo doesn't seem to show when they started to ocurr and how often. Maybe it was a fluke 6 months ago and therefore a red herring.

Unbeknown to me, I had a blocked DPF when I bought the car.
Some buffoon (probably the selling garage) had done a software DPF delete, and then hollowed-out the catalytic converter instead of the DPF.

It was fine when I test drove and on the way home from Birmingham to Nottingham.
The symptoms were not bad when first setting off first thing with cold engine but progressive loss of power as it warmed up.
It also ran hotter, not colder.
After a week, the turbo centre gasket blew due to the back pressure so I put a new £800 turbo on thinking that was the problem, still no power.

It took a while to find it was the DPF and another £400 later all sorted by removing the DPF and finding it chockablock with soot.

Luckily I bought the car for a great price and the dealer went bust a few days later.

Maybe your second thermostat beside the autobox is stuck open. There is a thread somewhere, and it's a £20 fix.
When you get some air through the radiator it soon pulls the temp down with this stat open.

I understand, I'll follow up on that thermostat problem ASAP as its a simple fix.

To be honest, I'm hoping it's not the turbo as thats going to cost a chunk!!

If it's just a controller or DPF needs some work, then that should be fine I'd assume (in cost comparison to an entirely new turbo!)

I was going to remove the DPF, but I'd be terribly upset should it not be the issue, and then have wasted that money that could've gone to something else. It's heartbreaking

I forgot to mention - when those codes are cleared, they instantly come back on when the engine is started.

Anyone?

It needs further investigation by someone who understands basic faultfinding procedures and has decent diagnostic tools.

I wouldn't waste your time changing parts until it's been established if you have one or more underlying faults.

ElsaWIN suggests there's a procedure for checking the actuator, which involves fitting a new link and confirming the turbo actuator is free and moves to where it's supposed to based on electrical signals received from the control unit.

This thread looks very similar in terms of symptoms and fault codes

http://www.vwaudiforum.co.uk/forum/s...den-Power-Loss

It needs to go to a proper VAG specialist with the necessary tools - the VAG tool for testing the control unit is 'Tester for E-positioner -VAS 6395-'

Thanks mate did have a look at that and will try to find a specialist in Birmingham by Friday to have a proper look at it. Central VW Audi told me £72 just to plug it into their machine... so not happy with that.

Anyway... I did some investigating...

I found that there are two actuators in my car, one at each side, and perhaps this is where I am hoping for some insight from you guys...

On one side, when the engine is off, the actuator is in the "up" position... but the other side is in the "down" position.

When the engine is on - the side that was "up" is pulled down, and only goes back up when I rev the car...

The other side however which started in the downward position does not move from its "down" position - so it remains there, and even under revving it does not move.

Could this be the issue? Or is this merely normal operation?

I'm not familiar with the Diesel engines but it would be a fair safe assumption that on v engines that actuators would behave the same on opposite sides of the engine, possibly in mirror to the other side but if one moves while revving and the other doesn't then it would point to an issue with that area.

Can you swap the items to see if the fault moves

That will probably be fault code 12597 intake manifold runners on 1 side

Okay cool info guys thanks

And yeah if that is that particular fault, would you think that this could be the reason for no power in the car? Or that there is another issue (the 13128 error?)

If the DPF was blocked, you would almost certainly have a warning on the dash and fault codes. It has temperature probes and back pressure sensors. It sounds like one of the inlet manifold flaps is broken for sure. I'm don't know if that causes your power problems, but it cant help. I have read about repair kits, but never had any experience of the problem myself *touch wood*.
http://www.fleethire.co.uk/images/bl.../DPF_light.png

Well some developments.

Definitely not DPF, as no warnings on the dash as snapdragon indicated.

I swapped the actuators for the inlet manifolds around from right to left to see if that moved the issue to the other side (thus pointing to a dodgy actuator) but that didn't do anything. The problem of the falling actuator happened still on the same side.

Took off all the ducting and pipes, and looked inside the manifold to see if the flaps were freely opening and closing when I manually moved the actuator - which they did.

It appears that the car is trying and failing for some reason to move the actuator on that one side, and instead defaults to leaving the manifold flaps open.

Again not sure if this is the issue or not -as the engine runs smooth still, and it should be turbo-ing up when I run it still. However that is not the case.

I also took off the turbo and had a look inside, its moving freely and is super clean. The actuator is also free to move around on there.

So basically, here I am - with not a clue in the world of what it could be though I know its going to be some small gremlin.

The real problem is this - I have agreed to part ex this car (before the turbo fault) for a new car. They gave me a low trade in value but I was happy as I was so excited to change car.

Now the issue is quite simple - I doubt they're going to take the car like this... and I don't have the px value they offered to me available in cash to continue the deal with them without the traded-in A8.

So I'm stuck... any ideas people? Or anyone want a bargain A8 if they know how to fix this issue?!

The inlet manifold runners do a sweep when ignition is switched on , so like you say you see the arm go up and down , in a good working condition each manifold motor does its sweep and the ecm does a signal compare between the both of them , if one of them fails the sweep test the ecm will switch that motor off line .

Biggest issue here is where the link rod attaches to the manifold arm the plastic end stops break off hence the codes .. upper limit/ lower limit not reached ....look at your code ,it's telling you just that .

There is link rod repair kits on eblag but the ones I have done always needed manifolds , the manifolds are on eblag aswell but I don't know what the quality is like ??

In the cases I have seen the manifold runners have NOT put the car in limp ...just put the management light on , depends on year and software level with limp issue

Next code ... turbo control .....
Is it vaccum control actuator or electric (hella unit)
If vaccum , with engine running take vac the pipe off the acctuator .... is there vaccum on the pipe , if yes when you put it on the acctuator can you see the vnt acctuator arm being pulled up to the stop screw.

If there is no vac on the pipe , trace the pipe back to the control solenoid , see if the control solenoid has its vaccum supply to it , systems normally have a vac resvoir somewhere which is kept under vaccum from brakes vac pump .

If the turbo control is electric , start and stop the engine whilst watching the turbo acctuator arm , it should do a self test sweep , if no sweep next tests would be wiring checks on the plug , dont want to go into that yet , just work through the procedures I have said
What year is yours by the way ?

Sorry just seen yours is 2008 , the last one I did was on a 57plate , so later models could go into limp because of the manifold runners , pretty sure it will be electric turbo acctuator at that year .
The turbo code could be a consequential code because of the manifold runner , but I still think the turbo acctuator will do a sweep when engine started and stopped , thus proving motor control is working .

Many thanks for your detailed reply.

The turbo actuator doesn't do a sweep. That's for certain. And as the turbo actuator unit and the two manifold actuators are the same part, I swapped all three around to see if the problem was systematic failure of one of the actuating units... but it isn't - the fault continued in the same place, regardless of which actuator was there.

Leads me to believe the computer (whichever one it may be) is shutting it down after start up on purpose...

I will of course have another play with it tomorrow!

Turbo actuator can cause the issues you discribed. Often intermittent however sounds like yours has thrown the towl in.
So your driving with the waste gate open all the time and not building boost pressure.

Sounds daft but could be cured with a throttle body alignment it can drop out of correlation and it relays on throttle position to give an accurate amount of boost to correspond to with throttle position/requested power.

Failing that I'd hazard a guess at a new turbo actuator motor +++

So you say the turbo acctuator the same part as the manifold runners .... definatley the same part number ??

So if you swap the motors around the manifold runner that does do its sweep correctly, if you try every motor on that bank do all 3 motors work ??

If yes ,you know its not a motor issue ....well still could be a tracking switch issue but i digress.........

Try leaving both manifold runners motors un plugged so the ecm will drop the limp status value into place for them , switch ignition off for a bit to allow for reboot then see if the turbo acctuator does its sweep .

In fact the sweeps may not take place whilst the codes are logged , the ecm can dissable the function. I assume you havent got a code reader that you can use to clear down .

Try this un plug both manifold runners plugs , dissconnect battery negative lead and hold over on to positive terminal for 30 seconds or so ...this is called HBR ...... hard battery reset ......it draws down all memory holding capacitors and any kam memory functions , then see if turbo acctuator does a sweep .

Lee

It's not identical part numbers, they have different letters at the end - but I've opened each one of them up to regrets the gears and I can confirm they are all identical parts for sure.

They have all been rotated and the fault has stuck with the same side, left side actuator - and it has always behaved the same whichever of the parts I have used at that time.

I unplugged the manifold runners as you suggested, gave it sometime and started the ignition... the turbo definitely did a sweep in this instance!

I don't have a code reader but my neighbour does - and these faults will not clear. As soon as you clear and start the ignition, they're all instantly back on.

I genuinely think there is an electrical issue and it is not as simple as I had hoped anymore.



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In other news, I've ordered the new car regardless of this trade in... I'm too tired stressing over the Audi! Welcome to the world of the Mercedes S Class :)

Sorry it's a struggle to fix.
Good luck with the S-class, I like them looks wise but never been in one, what model/age?
We used to have an 02 C-class and the quality was truly atrocious with regards to rust, electrical faults and supergluing broken clips etc.. I vowed never to buy another, but have they have since learned their lesson.
Please post back how it compares.

Thanks!

Well, I'm not too much of a fan of the brand new-new shape, because the last one was so aggressive. So I've purchased a 2012 W221 S-Class, AMG body kit, 50k miles... I get to pick it up after they complete their pre-delivery inspection, so likely Monday or Tuesday!

Some pics I took when I was there are attached here if you're interested... worth noting I took this particular one as 1) I've never had a white car, and this is a designo paint, and 2) it has a B&O sound system which quite literally ****s on the Bose of the D3 A8 I have!

Drive wise it's nice and comfortable, just kind of glides over everything. It's a strange one to describe, but it is nice, and you sit in a commanding position with a lovely long bonnet ahead of you. Space is aplenty and I just love it from every angle.

Anyway, aside from that basic overview, I have only really gone on a long test drive and played with it at the garage... so can't give anymore detail than what I have so far... once I have it here, I'll do something more detailed for you. :)

(Just blocked out the number plate in the pics) ... sorry they're so dull, wasn't exactly a sunny day when i took the pics...

I found the W221 cramped and claustrophobic, a bit like being stuck in a Mini with 5 other people. It's a big car but the interior space is pathetic IMO

Seriously?! I can only assume you went from an LWB A8 as a comparison then because by all measures the SWB W221 is far larger inside than the SWB A8 !

It was a SWB W221 I was in.

Dunno what to tell you mate, perhaps you grew between switching cars lol because by all measurements (wheelbase, interior cabin space in litres, width of cabin, height of cabin...) the W221 pips the A8...

I understand each to their own and opinions will vary on likes and dislikes, I am just contending the issue of you saying it was physically smaller and claustrophobic. Seems like a crazy observation but hey ho thanks for your constructive input :)

PS: Yes I assume you were perhaps comparing the SWB W211 with the LWB A8, hence that would make sense feeling claustrophobic! As of course the A8 LWB is going to be much roomier than the SWB competition.

I had never sat in an A8 when I tried the W221. I had a W220 at the time and comparing the 2 cars the W221 did feel a lot smaller