Audi A3 - Diagnosing the problem turbo or dpf - Free-man

Anyone any experience with this?

If an exhaust is badly fitted or if it has a blocked dpf, can it cause a rapid failure of a turbo? Trying to figure out if I need to replace a turbo or an exhaust.

When the engine is started white smoke pours out of the exhaust and some bluey tinted smoke slowly rises from around the turbo.

I was planning to remove the turbo, check its vanes and clean it, then if good maybe it is the exhaust is the problem?

Edited by Free-man on 22/03/2019 at 01:23

Audi A3 - Diagnosing the problem turbo or dpf - Oli rag

I would say it was most likely that the turbo oil seals and possibly bearings have failed, to cause that much white smoke.

Edited by Oli rag on 22/03/2019 at 06:30

Audi A3 - Diagnosing the problem turbo or dpf - paul 1963

Turbo is toast .....

Audi A3 - Diagnosing the problem turbo or dpf - Free-man

Ok thanks I'm gonna have a go at taking it off this morning might be able to part trade it fir a recon one. Should I be worried that if I replace it and the exhaust is dodgy it will break the new turbo?!

Audi A3 - Diagnosing the problem turbo or dpf - galileo

Ok thanks I'm gonna have a go at taking it off this morning might be able to part trade it fir a recon one. Should I be worried that if I replace it and the exhaust is dodgy it will break the new turbo?!

If the exhaust is clogged up enough to restrict flow through the turbine housing, the increase of pressure might reduce the life of the seals/piston rings at that end.

However, a blockage of that degree should badly affect starting and running anyway.

Edited by galileo on 22/03/2019 at 10:30

Audi A3 - Diagnosing the problem turbo or dpf - Gibbo_Wirral

Replacing the turbo could just end up in another dead turbo in the future.

Its possible that the car has other problems which has caused damage to the existing turbo along the way.

Audi A3 - Diagnosing the problem turbo or dpf - Free-man

So am thinking a good place to start is taking off the turbo and checking for damage. I'll drain the oil first then give it all a good clean and replace the turbo. Then see how its driving and any fault codes appearing. At that point I'll probably be able to tell if the DPF is a problem. So far I've the air flows off and found a small dried leaf in there that got through the filter somehow. Theres a little bit of a watery substance in the air flow tubing off the turbo, no idea what that is. Now looking for the oil pressure switch. Panicked earlier and rang a few garages for quotes. More than I can afford I'm afraid. Figure I can pick up a turbo from a breakers yard for 150 and give it a good clean, stick some new gaskets on it and fresh oil etc hope will do it.

Audi A3 - Diagnosing the problem turbo or dpf - Free-man

Took off the air flow manifold to the turbo and exhaust on other side, vanes appear perfect and everything is moving freely and feels normal.

Put everything back on bar the exhaust side and ran it - white smoke poured from the turbo. There is a smaller hose going from the middle north most part of the top of the engine to join into the turbo main manifold, like a spigot, and when removing that it had some oil in it. Is that supposed to be there? The turbo itself had a small amount of fresh oil in it.

Also, after turning off the engine, about 10 seconds afterwards there is a small sound at the front which sounds like a release of air.

Audi A3 - Diagnosing the problem turbo or dpf - Oli rag

Took off the air flow manifold to the turbo and exhaust on other side, vanes appear perfect and everything is moving freely and feels normal.

Put everything back on bar the exhaust side and ran it - white smoke poured from the turbo. There is a smaller hose going from the middle north most part of the top of the engine to join into the turbo main manifold, like a spigot, and when removing that it had some oil in it. Is that supposed to be there? The turbo itself had a small amount of fresh oil in it.

Also, after turning off the engine, about 10 seconds afterwards there is a small sound at the front which sounds like a release of air.

I know you said it feels normal, but I still suspect that the oil seals are worn causing the excess white smoke.
Audi A3 - Diagnosing the problem turbo or dpf - Free-man

I sure hope you're right oil rag! Wouldn't that mean I'd just need to replace the gaskets between where the turbo flanges meet the engine block

Audi A3 - Diagnosing the problem turbo or dpf - focussed

Basic turbo diesel design characteristics are that the turbo is sized for an engine to run the exhaust turbine at a safe temperature and nominal exhaust backpressure. An increase in backpressure, such as a blocked DPF will increase the exhaust temperature in the turbine beyond it's designed limits. Whether that will result in failure depends on how close to critical temperature the turbine is when running with normal backpressure.

Audi A3 - Diagnosing the problem turbo or dpf - S40 Man

Does the Audi have a DPF pressure sensor? My 04 Volvo s40nl and now 08 mondeo have DPF and both had a pre and post DPF sensor so the car knows when the filter is full and needs a Regen or to at least warm the driver via dash light.

Would that be a good place to start?

Audi A3 - Diagnosing the problem turbo or dpf - Free-man

I think I need diagnostics done on it.

So with the exhaust, my presumption is that if I've disconnected it from one side of the turbo, and the smoke is still pouring out of the turbo, then it rules out the exhaust as a problem?

I'm also wondering that if, when driving, the turbo went off, maybe protected by 'limp mode' (no idea if it is in limp mode, just presuming), then how is the turbo still responsible for the white smoke?

Why would leaky oil gaskets produce white smoke? Is it because they pull air into the engine where there shouldnt be normal air?

I want to give a history of this problem for clarity -

1. Picked up car, lots of smoke from exhaust and through bonnet

2. Tank near empty, filled with diesel.

3. Driving ok, sucking effect of turbo audible as if rain lashing windscreen when kicking in.

4. After driving for 50mph mostly over an hour, brought it up to 70mph on motorway and heard a small pop or something. Glow plug (coil) light began flashing on dash and car lost all power bar power enough to drive another 30 mins.

5. On starting now, glow plug light not flashing however have pulled the battery so maybe a reset.

Audi A3 - Diagnosing the problem turbo or dpf - dieselnut

White smoke gets produced by the turbo when oil leaks past the bearing seals due to wear.

If it is leaking on the inlet side ( not so likely ), the oil gets blown into the inlet & partially combusted in the engine which could come out the exhaust as black or white smoke, depending if it get completely combusted.

If the turbo leaks on the exhaust side, the oil hits the hot turbo casing & hot exhaust gas & gets vapourised causing white smoke.

So if it smokes straight from cold it's unlikely to be leaking on the exhaust side, as the turbo will still be cold.

But bear in mind that the engine may be trying to regerate the DPF, so will inject extra fuel after combustion, this also gives white smoke to burn in the DPF to heat it up.

You certainly need some diagnostics done before you go any further.

Limp mode only reduces the engine fueling, the turbo still spins & leaks oil if the turbo is faulty.

You would probably be best to go to a diesel specialist as there are other causes for a diesel engine to produce white smoke, they will have all the specialist test gear.

Audi A3 - Diagnosing the problem turbo or dpf - Free-man

Ok so I've bought an old vagcom cable and software. Hopefully works, going to plug in tomorrow morning.

I've put a video up on YouTube of it too. Have a look. youtu.be/Y2In6dbwcts

Audi A3 - Diagnosing the problem turbo or dpf - dieselnut

That engine sounds really rough, plus you can see it rocking back & forth due to the poor running.

I would guess the smoke is from the engine itself.

If you've just bought it, take it back for a refund.

Be interesting to see what the diagnostics reports.

Audi A3 - Diagnosing the problem turbo or dpf - Free-man

I wish I could take it back. Privately bought I'm afraid

I've been under the car today and it is absolutely covered in oil. Theres a felt cloth guard under the engine block soaked in oil. Maybe the sump is leaking or is full or too much oil put in it. The dipstick says lots of oil.

I also ran the car while watching the coolant tank. Not one bubble but maybe it only shows when hot enough.

Still scratching my head as to what this could be. Taking off the turbo would be a right pain to get at the nuts.

Pity I cant upload pics on this forum. Going to do the vagcom shortly.

Audi A3 - Diagnosing the problem turbo or dpf - Free-man

As you can see the turbo to DPF clamp is not doing its job as is leaking smoke.

Audi A3 - Diagnosing the problem turbo or dpf - elekie&a/c doctor
I’m with mr dieselnut on this. The engine is not running evenly on all cylinders. You could have excessive crankcase pressure or oil blow by in the cylinders. You are going to need a miracle to fix this with vag com. I would check cylinders compression before throwing any money at this
Audi A3 - Diagnosing the problem turbo or dpf - Free-man

Ok so just ran the diagnostics using vag com vcds with the engine running.

01 engine status malfunction

3 faults found

4817 leak in air intake system. Engine speed 2136.5/min. Normed load value 91.8%. Vehicle speed 105kmh. Coolant temp 83°c. Intake air temp 13°c. Exhaust gas temp sensor 1 -0.0°c.

10065 Mass air flow sensor G70. Intermittent. Fault priority 2. Engine speed 921.5/min. Normed load value 100%. Vehicle speed 0kmh. Coolant temp 12°c. Intake air temp 13°c. EGR solen. Val actual value 99.5%. Charge air pressure specified value 864 hPa. Charge pressure actuator acknowledgement 18.23%. Air mass specified value 699.7mg/stroke. Air mass actual value 3276.7mg/stroke.

4986 Cylinder 3 Glow plug circuit Q12 electrical fault. Engine speed 910.5/min. Normed load value 100%. Vehicle speed 0kmh. Coolant temperature 5°c. Intake air temperature 6°c. Preheat time 2500ms. Glow status bits 0-7 0. Glow status bits 0-7 112. Outside air temperature 5°c.

There were also 4 faults found in the Auto HVAC which I am thinking are probably related to the main problem.

Audi A3 - Diagnosing the problem turbo or dpf - Free-man

Removed the connector to the MAF sensor and the smoke has stopped on one side. The shaking is a bit better too. Trying to figure out why now.

Audi A3 - Diagnosing the problem turbo or dpf - madf

MAF sensor covered in thin dirt layer. Clean carefully using aerosol Carb cleaner- do not touch wire..

Audi A3 - Diagnosing the problem turbo or dpf - Free-man

I sprayed it with electrical cleaner and put it back on. The VCDS isn't picking it up as a fault now and the smoke isnt as bad.

But I also unplugged 2 glow plugs and immediately noticed smoother running and less smoke. As the engine warmed up, the smoke returned to normal. There is clear fluid pooling in the exhaust tip.

I've cleared DTC in VagCom and the engine is now reporting no faults however I then unplugged the MAF and cant understand why an autoscan in vcds is not showing the MAF sensor and the glow plugs now? Does clear DTC tell the car to ignore the faults so they are no longer reported? I presumed they would be there continually as long as theres a fault.

Still have smoke from the v band clamp from the turbo to DPF. Maybe can wrap some tin foil around it or something.

Audi A3 - Diagnosing the problem turbo or dpf - dieselnut

I take it this is either a 1.6 or 2l common rail diesel.

You have reported that the oil is over full.

This is probably due to uncombusted diesel adding to the sump oil & diluting it.

Be very carefull, the engine could just run away on its own oil if it gets too full & self distruct.

On one of your readings it reports " Exhaust gas temp sensor 1 -0.0°c", so this sensor can't be working if the engine was running. This alone could prevent the DPF from regenerating.

The rest of the faults won't cause all that smoke.

Use your VCDS to look at Injection Quantity for each cylinder, i'm sure they will be all over the place.

I really think you should take it to a Diesel Specialist & get an estimate from them before spending any money on this.

Edited by dieselnut on 31/03/2019 at 19:53

Audi A3 - Diagnosing the problem turbo or dpf - Free-man

Thanks dieslnut.

So I realised with the VCDS that those readings are from a week before I got the car.

After doing the work on the glow plugs and MAF sensor today the VCDS autoscan is reporting no engine malfunctions.

I actually took the car out on the motorway this evening and turbo is working fine. Not noisy, plenty power. However when driving it fast the coil symbol light (engine control malfunction light) blinks and there is no power although it still drives. This goes off when the engine is turned off, and when back on the turbo works fine again. Someone suggested sticky vanes due to carbon buildups and to spray Mr muscle in?

I think you are right that he oil is a problem. It has been over filled and I think the sump needs to be drained, cleaned and resealed. New oil and fuel filter and general cleaning.

I'm afraid of what a garage will charge me just to look at it. They'll likely say hey need to keep it in a few days and will come back to me with an astronomical quote. I figure If I fix the obvious bits first then if no joy send it in.

Audi A3 - Diagnosing the problem turbo or dpf - dieselnut

I'm pleased you've got it running better, but if the coil light is flashing & going into limp mode, it must be throwing up some codes.

You may need to scan it before you switch off the ignition.

Check that No1 Exhaust Temp sensor again & check the DPF Carbon Mass.

If the DPF gets too full it won't regenerate at all.

Certainly see to getting the oil & filter changed.

If it's diluted with diesel it won't be lubricating nearly as well.

Audi A3 - Diagnosing the problem turbo or dpf - Free-man

Ok so had a chance to take it out for a bit tonight and then scan the codes while idling afterwards. Made sure to get it into limp mode again.

2 engine faults showing - 4817 leak in air intake system, and 4986 cylinder 3 glow plug circuit.

The dates and times coming up in these are different which is throwing me a little.

The exhaust gas temp sensor is still showing as -0.0 so maybe it is faulty or needs a good clean. No idea how to check the DPF carbon mass?

Going to try cleaning everything over the weekend and changing the oil.

The error information for the air leak are

MIL ON

Date 2019.03.24

Time 04:27:23

Engine speed 2222.00/min

Normed load value 98.8%

Vehicle speed 86kmh

Coolant temp 78°c

Intake air temperature 16°c

Ambient air pressure 1010mbar

Voltage terminal 30: 14.780 v

Coolant temp at radiator outlet actual value 51.5°c

Bypass valve for EGR cooler status Bits 0-7:1

Exh.gas recirc shut off conditions Bits 0-7:0

EGR cooling function status Bits 0-7:0

Exh.gas recirc (EGR) cooler pump specified value 94.84%

Temp sensor for EGR after cooler raw value -270.6°c

Exh. Gas temp sensor 1: -0.0°c

Audi A3 - Diagnosing the problem turbo or dpf - dieselnut

You havn't stated what engine this is, what is the engine code.

What code reader are you using, VCDS will give the best results.

From your diagnostics there are a few anomolies:-

Voltage terminal 30: 14.780 v - shouldn't be more than 14.4v. Check the battery voltage when engine is running.

Temp sensor for EGR after cooler raw value -270.6°c, something not working there.

Exh. Gas temp sensor 1: -0.0°c, i'm fairly sure the DPF won't be getting regen until this is fixed & DPF will slowly be filling up.

I think your air leak could be a partially stuck EGR or there is a leak in the air pipework between turbo/ intercooler/ inlet. But the latter should be giving underboost error.

 

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