black smoke no power help

[minty0_10]

hi all just bought a 1999 a4 tdi problem with the car is the lack of power.
when the turbo suposed to kick in it just blows out black smoke so im guessing the turbos dead.
but while driving today i had no power from the turbo at all (there was a little before) but also no smoke the car was struggling to pull past 60 and also had a slight miss at the higher rev range but not all the time. then sometimes the black smoke comes back and a ever so little bit of turbo pull,

so if it is the turbo how much am i looking at for a new one and how much work is involed in fitting it

sujestions anyone thanks

[Huweth]

Have you ckecked the boost pipes? Sounds like one is very loose!

[minty0_10]

yes ive had a look around nothing that i can see. i would have thought if a pipe was holed or off you would be able to hear it?
what would cause the black smoke to come and go?

[Huweth]

I would have thought you would have heard a big pop when it came off but if you bought the car already like it then you wouldn't have! Some of the pipes are probably very hard to see/access properly, maybe a knowledgable mate could have a look? If no pipes are off, then it could also be that the intercooler is blown. The black smoke could be caused by overfuelling when the turbo should be boosting but can't. Of course, it could be something else entirely. Can you get it on VagCOM?

[minty0_10]

it only smokes when the turbo coming it theres not a lot of power when it does mind. but then a lot of the time theres no power from the turbo at all when that happens theres no black smoke either in other words

when the turbo tries to work there smoke
when its not working at all no smoke

whats vagcom?

[minty0_10]

just been out to the car now and checked all the intercooler pipes cant see any holes or splits. ive also taken the inlet pipe off the turbo cant feel any play in the shaft either.

[Huweth]

Hmm this is strange. It's still sounding like boost pressure loss.
VagCom is the software you connect to the using a laptop that can tell you all of the electronic functions of the car. If there are any faults detected it will highlight them, and you can also see various readings from different sensors which can help you diagnose faults.

Ah, I just thought. You might also have a severely blocked intake manifold. It can cause fuel/air starvation issues giving similar effects. If you are mechanically minded it's not too difficult to remove the manifold and check it. Should take a few hours to do and is always worth cleaning. Don't try to clean it on the car as any debris that gets into the engine will be catastrophic!
How many miles has the car done?

[minty0_10]

the cars done 150k i have found a small vacum pipe off at the back of the engine i conected it back up and there was a diffrence made in 1st and 2nd gear. rest of the gears still flat with no boost. its not smoking as much now either but its a still long way off runing as it should be.

[Huweth]

At 150K miles the intake manifold could very well be sooted up. The fact that a pipe was off at the back suggests someone has been prodding around. I reckon the first thing to do is get the intake off. All it will cost is some engine cleaner and maybe some tools.

[minty0_10]

ok i,l have a go at that is that a coman problem then?
i also have a 98 tdi passat with 260k and still pulls well.

[Huweth]

Yeah it quite common. The EGR (exhaust gas recycling) valve shunts gas into the intake. If that gas is sooty (which it is on a Diesel) then it gradually clogs the intake, sometimes to the point where it causes what you've been experiencing.
Some cars get it, some don't.

[minty0_10]

wheres the EGR valve

[Huweth]

It will be on the top of the engine poking through the plastic engine cover probably. It's a round disk/mushroom shape and is silver/goldish in colour.

Here's a pic I just stole from another site.
http://pics2.tdiclub.com/gwillie/VW/Sballintake/INTAKEMAN101_files/sm000106.jpg

And here's a pic of the crap that can come out...
http://pics2.tdiclub.com/gwillie/VW/Sballintake/INTAKEMAN101_files/sm0000g2.jpg

If you want a link to the 'how-to' on another site PM me and I'll send it to you. I don't want to post the link publicly as I don't want to advertise 'the other site'...

[minty0_10]

ive not got that valve on my engine. its the older coman rail type not the pd. i have been driving the car around today and the more i have been driving it the better it seems to be getting. its like flicking a switch with the turbo coming in and out.

no power then all of a sudden power the turbo also seem to work better if the throttle peddle is not push to the floor.

[Huweth]

Thats what comes out of the manifold.
Is the turbo coming in at about 2000 RPM? Thats what it should do. You might now be cleaning all the pipes and intake crap out slowly if the problem was the vacuum pipe. I'd drive it around for a while, pushing the car hard from 2000 RPM up to 4000 a few times a day. Getting the turbo hot and the pressures up will help keep everything clean. I push my car everyday on the same slip-road for about 20 seconds.
Does the turbo not seem to work at full throttle? Thats odd, but of course might improve with time. Give it a while to see how things go before you go spending money.

[minty0_10]

1st and 2nd gear are fine now just starting to get some boost through the other gears. but not throughout the rev range after say 2,000 then stops at 3,000 revs and feels like its holding back.

something seems to be telling me fuel starvation or low feul pressure

[Huweth]

In that case it could be the vane adjuster, or very possibly the fuel filter.

[minty0_10]

i was thinking filter. what and wheres the vane adjuster! what ever happend to simple engines!

[Huweth]

The vane adjuster is to control the amount of boost from the turbo. It changes the angle of the vanes in the turbo to provide more/less boost according to it's speed.
The fuel filter should be very easy to change. Parts are cheap (£15?). If you do change it, use new seals as the old ones damage easily and will leak. Since it's pre-PD you need to prime the filter by filling it with Diesel before you fit it. Other that that they are just 'plug and play'.

[ini]

If your turbo is a VNT and has not been operating properly for a long time (not many long journeys), there will be a build up of crud around the variable vane mechanism.

This will generally cause a loss of boost in 3rd gear upwards over 3000rpm & under high load (hills etc).

Go for a very long drive and give it some welly, or dismantle the turbo and scrape out the soot.

[minty0_10]

now thats seems like whats happening. whats the vane look like.

[ini]

They are little pivoting aerofoils inside the body of the turbo.

[minty0_10]

would it be worth spraying some wd40 up the air intake of the turbo.

[ini]

Dont spray WD40.

You can buy a spray specifically for this purpose from the USA, but i never trust any of these kind of products not to do bad things to oil seals/gaskets etc.

After many years use, i am now allergic to WD40 and 'back to black'.

[snapdragon]

Back to basics, you are getting black smoke, you get a sudden boost of power that throws you back in the seat, it is possibly the EGR valve being stuck open when it shouldn't be and when it closes, you get the sudden power. This is why you get black smoke too. Usually a weak turbo doesn't give this as the air is metered anyway, so less air = less fuel. Can you disable the EGR by disconnecting the vacuum pipe and blocking the pipe to stop there being a vacuum system leak?

Also, you found a vacuum pipe, off this causes dirt and dust to get drawn into the vacuum system, whereas a vacuum system really just pulls air around in a closed system, you had an open system, so it was pumping air insead of pulling a vacuum. This can cause the dust to ruin pressure converter valves and non-return valves.

[minty0_10]

theres no smoke at all now since i coneted the pipe back up pulls like it should in 1st and 2nd. im going give it a long run tomorrow to see if i clears its self up at all.

[I_am_stealth]

I believe you had two problems, you fixed one of them..
The second problem you might have seems to be the variable geometry of the VNT turbo. That is a common problem..The vane control mecanism may need cleaning, and that is all.

[minty0_10]

i dont think its going to mater much now if there a hole or not there.
i was hit up the back side tonight by a landrover discovery. must say through what a well built solid car the a4 is. back hatch has had it. but rear quaters and boot floor are un marked!
still down to the insurance to sort it out for the time being.

[I_am_stealth]

Sorry to hear that....

[minty0_10]

mmm gutted was a nice car with all the toys to.
no sure if it will be repaired or not from what i can see its going to need
back hatch and glass
1 rear quater glass
bumper
and rear light.

[Huweth]

Gutted, do you think the turbo has been damaged in the crash also? ;)

[minty0_10]

if only

[barney2]

hi Minty,
what a great pity your car's dead. I followed your symptoms with exitement, my car's a audi a6 1.9tdi avant. and has the exact symptoms. Smoke with little turbo power pulls in 1st and 2nd dies off in 3rd. No smoke and no power at all. I've changed everything apart from the turbo. Each time work is done on the fuel system it runs well for a while,then nothing.
please help.

[I_am_stealth]

Well, have you checked all the piping from the turbo-intercooler-inlet manifold?
If you are getting black smoke you should not be running excess of fuel/shortage of air... I strongly recommend you to check the thick tubing coming from the turbo-inlet manifold. Very likley that to be the reason.
Alternatively you could do with a log using VAG com, that way it will be obvious if your required pressure values are not achieved.
What do you mean by "it runs well for a while, then NOTHING?"

[barney2]

thanks for that stealth,
I would have to get that checked out at the garage, only i do think there is something wrong with the fuel system dragging in air..i did have a garage change out the fuel filter afterwards the turbo worked fine for a few minutes then nothing ...no turbo power no kick in the back feeling. I have read somewhere on here where a guy changed out the deisel lift pump cause it was dragging in air is this possible?
thanks.

[I_am_stealth]

Barney, I think what you are describing there is a limp mode. If the ECU detect a pressure difference between required/measured values will go into limp mode. That might take a few minutes, depending on load. I have a VAG com interface, if you live around Leeds/York ( I work in York) I might be able to help you. If you replace your fuel line with a transparent one, you will be able to tell easily if you are getting bubble there. ;)
The rule is: if you are getting air, you are NOT getting smoke ...You said you were getting smoke too.
I strongly believe that your problem is a simple one...Don't start replacing parts unnecessarily...

[barney2]

hi stealth,
when i floor it in 2nd sometimes the turbo kicks in and i feel power all be it not that much and there' s black smoke out the back. At other times the turbo doesn't kick in there's no power and no smoke out the back. In both cases it will reach 90+mph so i don't think is in limp mode.

[I_am_stealth]

Hmm, is it the VNT15 turbo on yours?
110 PS model? Non-PD?
I am wondering if your turbo actuator does not stick, or your geometry is stuck on vanes closed (high reving)...
That means you will not feel the boost, only at high rev. That would mean not enough air at low rev too, therefore maybe black smoke. However, you might have two separate issues, from what I understand.
What is your milage? Have you ever cleaned your turbo?
Your turbo works all times, you will start feeling the boost only when its value is more than the atmospheric pressure. The boost mot reaching higher values might be:
stuck actuator(even dirty turbo if VNT), N-75 valve not behaving properly all the time( not likely ), hole in the tubing( pressure loss), faulty MAP, faulty MAF.
I can't think of something else likely to give you the "dead" turbo feeling. OF course could be a limp mode, but if you always can go at 90mph, it is not the case.Have you notice a difference when is cold /warm outside, engine cold/hot?

[barney2]

hi Stealth, is a 1.9 tdi 130pd don't know what type of turbo all i can see is inlet from exhaust, oil pipe ,discharge pipe and vacuum pipe...i can't see the turbo actuator is it underneath? bought it at 111000 miles has now done125000miles. i haven't cleaned the turbo. where is the N75 valve? i changed the MAF. there is no difference if it is hot or cold. it seems to run ok if left on a level surface for an hour or so. strangely, the brakes feel stronger when it runs well...i've had all vacuum pipes checked at audi garage. brake works at higher point in travel and uses less throttle. might be a red herring...

[I_am_stealth]

Right, as far as I am guessing you have a variabile geometry turbocharger, I imagine it will be a GT1749V turbocharger ( AKA VNT 17 ). Engine code AWX or AVF i think.
The variable geometry vane cleaning job is not trivial, however it can be easily perfomed easily by someone who knows what he is doing :) .
But before you decide to do that ( if you do) you HAVE to diagnose it with something like VAG com interface. Like I said, If you are in the Leeds/York area, I could help you with that. Before you think about the turbo, you have to eliminate everything else though. If the milage was done in city driving, your turbo variable geometry might be dirty.
It is very strange what you are describing about the brakes. Some people report water getting into the servo drum through the vacuum inlet. I could check that if I were you. Have you ever found water in the battery compartment? If so, you have to clean/unblock the bottom holes!
I can's see how it can be related to the smoke...
N-75 valve controls the boost and connects the Turbo actuator with the air filter hose and the post turbo hose. It is a three hose going into "something" ;) , one at the bottom the others on the top/sides probably. I am not sure what is the model for yours, but I could find out if I am sure of all your car details..


brake works at higher point in travel and uses less throttle. might be a red herring...
did you mean accelerator ? not sure what you mean by "higher point"

[barney2]

hi Stealth,
The car has been checked via vag.com stationary and on the move....no faults found. I would need a garage to strip the turbo. I forgot to mention it has had a remap in process of finding the fault this has made it more responsive but i know it is still not right. It has had a recall on the plenum chamber and audi removed the rubber bungs below the battery and servo.
thanks for your help so far.

[I_am_stealth]

If you can send me the turbo log from the Vag com I might be able to help more. However, if you had it remapped things can go funny sometimes, particularly for a car with 125 k and particularly regarding smoke ... It depends a lot on the map. Who did it? Any idea how aggresive was the re-mapping?
I have no more ideas on what to suggest. I have to see pressure values, etc in order to be able to draw any conclusions regarding your turbo.
I would be happy to help as soon as you come up with any more info.
Good luck.
But before doing anything else I would check the hoses coming from turbocharger and going into the inlet manifold, maybe there is something you haven't notice before :approve: