Smoking exhaust, needs cleaning out, how?

Take it for a minimum 2hr drive, at c60mph.

it needs heat, and to heat it right through takes time.

Can you force a DPF regen. That should heat everything up nicely..

it doesnt have a DPF.
Its done >100miles since rebuilding,, did 25miles yesterday at 3500rpm, mostly
To get the heat, does it have to stay at high revs for a long time, or keep it under load continuously(accelerate up a big hill all day)?

To get the heat, does it have to stay at high revs for a long time, or keep it under load continuously(accelerate up a big hill all day)?

The wider open the throttle, the more exhaust will flow and the hotter it will get. Ideal thing would be towing a heavy trailer up a steep hill in first gear.

Keep it above 50, it’ll get hot enough regardless of how you drive it, the important thing is to do it for long enough.
if it takes , say, 10 minutes for the temp gauge to be at normal, it’ll be double that for the bottom of the engine to be at normal, and then double that again to warm the gearbox right through. S0 40 mins.

So who can lend me a heavy trailer, and a steep hill?

So who can lend me a heavy trailer, and a steep hill?

You can take my boat to N Wales for me at the weekend - by the time it's loaded with 350L of fuel it will weigh about 2000kg!!

Is the exhaust exposed  and easy to access?  Maybe try heating with blow torch to burn off the remaining oil?

Go for a day out somewhere that involves say an hour+ drive each way... I'd imagine that would probably sort it out.

You want to not only get the exhaust hot, but keep it hot long enough to burn off any residual.

Unless you've got an MOT coming up just drive it as normal and it'll gradually go. It really makes no difference to emissions, you're evaporating the same amount of oil just over a longer period and without the extra driving and higher revving to accomplish the same thing a bit quicker.

Park it facing downhill on a steep hill so oil flows back towards the hotter parts of the exhaust?

Was going to suggest the reverse so you end up with a puddle of oil under the exhaust tip but you'd need a *very* steep hill.

Italian Tune Up

Intercooler probably full of oil if you turbo seals blew.

Whip it out and wash it in petrol, then hot water.

Will smoke for a long time if ots clogged.

<p style="text-align: left;">Clogged with what ?</p>
I mean surely no one that's replacing a turbo hasn't already cleaned the intercooler -its 101 to clean the intercooler in such a situation.

As above, revs and heat. I just took mine out at night for a few thrashes. It took a surprisingly long time to stop, the crossover between "gets hot enough to smoke" and "doesn't get hot enough to burn off quickly" was pretty big.

the intercooler itself .hasnt been touched
its now been for a 50mile run at 60-70 and over 3000rpm

if its slightly overfilled with oil, would that affect it in this way?

I mean surely no one that’s replacing a turbo hasn’t already cleaned the intercooler -its 101 to clean the intercooler in such a situation.

You might think that.

In this case, not been touched.

Clogged with what?

Dutch wooden clogs., various sizes from 7 to 9, some left, but a surprise amount of right footed ones.

Or its clogged with air, the really thick, dense heavy version of air.

Thats 300 miles at a good pace now, still smoking on idle.
If there was an intercooler problem, would that only affect things when the turbo is active?
The car did not smoke before, that i noticed, so what else can it be?
If the engine was overfilled with oil before, would that force oil through valve stem oil seals and out through the exhaust? and if it did, would the valve stem oil seals be damaged, so it would continue to happen?
Do i need a compression test?
Its done >160k miles
its done my head in too. Im leaving it alone till next week

What colour is the smoke?

Clogged with what?

Dutch wooden clogs., various sizes from 7 to 9, some left, but a surprise amount of right footed ones.

Or its clogged with air, the really thick, dense heavy version of air.

So you have no idea if you just say that next time thanks

<p style="text-align: left;">If there was an intercooler problem, would that only affect things when the turbo is active?
The car did not smoke before, that i noticed, so what else can it be</p>

If not from the 1980s the turbos always active In some form.

If the intercoolers full of oil (but not blocked - as that would manifest considerably more issues than smoking )  then it'll be feeding oil contaminated charged air to the engine and onwards to the exhaust

As I said after a failed turbo it's absolute 101 to pull the pipework and intercooler to clean so that's where id be going if as you say it's not been done.

Surprised no-one has suggested the obvious...

That only works on de-catted imprezas.

If there was a build up of oil in the intercooler, then you would have known about it quite quickly, as the first time there was enough air flow to suck the oil in, the engine would have runaway as it ran on the oil.

Was the only symptom of the turbo failing oil in the exhaust?
Or was there other issues like loss of power?

If the engine isn't burning any oil, then it is likely just a build up of oil in the exhaust, which can take a very long time to burn off without any other intervention.
If you're really concerned about, taking the exhaust off and pressure washing it will help. By now it's probably only the rear silencer that's likely to still have oil in it. Easier option could be to just stick a power washer up the tail pipe.
Only thing to be aware off if you do wash the exhaust, is it will result in a lot of water vapour/steam as it dries out. You ideally want to do it where nobody will complain about clouds of smoke/vapour being produced.

I know what it is probably clogged up with. You know  what it is probably clogged up with. Yet you still felt the need to ask me to clarify what I thought it would be clogged up with. Then you bought a keyboard with no punctuation keys ,  to belittle me with a rubbish one liner pertaining that I know zero about the inner workings of a chra.

its a major operation (for me) to remove the intercooler, and people i spoke to didnt deem it necessary.
There was a loss of power, and something had gone into the turbo and bent the fins
so i got a new chra

At this point, cleaning the intercooler isn't going to help.

It being blocked is highly unlikely, as it would take more than a few bits from a turbo to block an intercooler to the point it affected performance.

Also given the mileage travelled, anything that was going to make it's way through the intercooler and into the engine, will now be embedded in the engine or out the exhaust.

The smoke is either residual oil still in the exhaust, or the turbo failing has caused internal engine damage and the engine is burning oil. Which is why I asked whether the engine is burning oil.

the oil level is pretty constant.
The smoke does smell of oil, and is grey/black, and coolant level is the same.
I'll take the exhaust off for a pressure wash

The smoke should be blue if it is oil burning.

Yeah black is running rich.

Did you get a warranty on the turbo work?

If the smoke is grey/black as you say, it's more than likely a fueling issue. IIRC I had the same issue when I changed the turbo on my VW caddy 1.9tdi in 2015. I had mixed up two of the vacuum hoses when putting it all back together.

My turbo went like a screaming banshee two days after I hit a massive pothole. Two of the turbo impellers (boost, intercooler side) had split, but didn't actually break. I would want to know what wrecked your turbo in the first place. They don't just blow for no reason and it could indicate another problem if a bit of debris has actually ended up hitting the impellers.

supremebean
Free Member

The smoke should be blue if it is oil burning.

Yeah, but in practice this isn't always useful. Can be, but you've got to be pretty brave to diagnose based on colour

Has any one mentioned grenaded intercooler or pipe leakage

im sure i got the vacuum hoses on the right way.
not so sure on the smoke coloue, but its not white.
Dont know exactly what happened with the turbo,was just overtaking a bus when it lost power.
Prior to that i tried mr muscle to clean some carbon out of it

Boost pipe?

Yeah, but in practice this isn’t always useful. Can be, but you’ve got to be pretty brave to diagnose based on colour

Isn't always useful? But it can be?

It's not a diagnosis, it's a starting point towards diagnosis.

Anyway, as molgrips has mentioned, i'd be checking the boost pipes. Get someone to rev the car in neutral and check all the joints. Should be pretty obvious if a connection has gone. The vag boost pipes have a little lug that the circlip locks on to and they can wear away over time, particularly the pipes going in to the intercooler.

Also, does it smoke immediately on a cold start up? Or does it build up with heat?

It used to be the practice to 'de-coke' exhausts on little motorcycles back in the day to slosh petrol down them (off the bike obvs) and then light it.
Not sure it actually achieved anything in real terms but, it was a thing.

I did it once to my little Rxs100, lit it, and the resulting explosion put me backwards onto the floor, luckily still with eyebrows.

Ah, those golden times of flammable liquids and low common sense...

In my experience turbo cars do not 'run on' from the oil in the intercooler.

Mostly its from the pcv system, is contaminated and heavy. It sits in the bottom of the intercooler and the air moves across the oils surface. It does not get picked up and lifted in great quantities. It can make its way through the engine unburnt as it wouldn't be atomised in any way. Also old engine oil has low cetane so not likely to ignite.

Cars that run on usually get new oil from the sump, crank slap from massively overfilled sumps mist the oil. The pcv system blows this into the intake and self combustion occurs.

Knackered thrust bearings would allow more oil from the chra either downstream to the exhaust impeller chamber, or upstream to the intake compressor wheel, and through the system to intercooler, then potentially up the intake tract to the head. However, i have seen 3mm float on a turbo and no oil was getting by.  And have rebuilt turbos with new bearings that still smoked after a refurb.

Back to the op. How much end float was there on the old turbo? Strange its still smoking with a new turbo on it.

My favourite boost pipe check is to wind the window down and find a road with a wall next to it. You can hear the hissing and whining. Or have someone else drive past you as you listen.

The exhaust isnt smoking on cold startup
Booest pipes were fine, i cleaned them.
Not sure how much end float, but more than with the new chra.

I wonder if it's not the catalyst. Have seen smoke with a aftermarket cat not getting up to temp. Problems disappeared immediately after fitting oe cat. But not until the garage guessed it was the turbo and we drpp. dropped a grand on exchanging a perfect turbo trying to get to the bottom of the smoking exhaust.

Just to be clear, are you still driving with the tankful of fuel with the (double dose of?) engine / injector cleaner in it? I wouldn't be surprised if whatever's in that gave you more smoke while you're actually running it.

I'd not worry too much until you've run the tank low and refilled with plain fuel and see if it's any better then.

The exhaust isnt smoking on cold startup

This, makes me think this......

Yeah black is running rich.

Turbo isn't doing its job for some reason, ECU thinks it is, dumps in more fuel than can be burnt.

Either:
- blockage (intercooler)
- some sensor not plugged in
- some pipe not connected/split

Or:
Knackered injector and it's been smoking for ages, the resulting coke killed the turbo.

I refilled just a few miles back as i was on reserve.
It runs very well, with new turbo and stage 1 etc, but i'll get vcds on it this week too, see if i can figure out how to get a graph of expected vs actual boost. And egr figures too

VCDS tells you expected vs actual boost and the same for most readings.  Of course the 'actual' is only what its sensors are telling it, so a bad sensor would not show up here necessarily (depending on what it is).

It runs very well, with new turbo and stage 1 etc

Wait.

You had a knackered turbo.

The garage exchanged the CHRA, didn't clean out the intercooler, dumped a load of snake oil into the fuel and performed a "stage 1" remap?

This just gets better and better *facepalm*

who said anything about a garage?
sometimes you gotta do things yourself.
Like fix a puncture. Or learn how to ride around a corner, one has to think for oneself
I dont want a garage in charge of my financial situation if i can help it

My apologies, I wrongly assumed the "people you talked to" were mechanics and had some hand in the job.

So to revise:

You had a knackered turbo after some unknown foreign material got in and caused enough damage to bend the fins.

You exchanged the CHRA, didn’t clean out the intercooler, didn't investigate what got into the turbo, how it got in there or where it subsequently ended up, dumped a load of snake oil into the fuel and performed a “stage 1” whatever that is?

Now it's running like shit because presumably whatever caused the initial damage is still in there and has either been ingested by the engine (or still is) or is trapped in your intercooler, possibly in bits.

I dont want a garage in charge of my financial situation if i can help it

In this instance I'd say you're costing yourself more in the long run. If there is loose foreign material in there then where do you think it's going to end up? Your valve seats and the hot side of the turbo before the cat and DPF (if applicable). If it's oil then you could be clogging your DPF and poisoning your CAT. This is why you are supposed to check everything downstream before restarting and you especially DO NOT restart until you know exactly what caused the turbo to fail.

It's not a difficult job after pulling a turbo. It's two pipes and some brackets, worst case it's water cooled and you need to change the coolant. Big deal.

I used to clean out my RD350 'spannies with a caustic soda solution, tie wrap some plastic over the header ends and fill them up. Please do check what your exhaust is made of before doing the same, mine were all steel so no destructive chemical reactions.

The best way I have found to work out when your car smokes is to drive at night on an unlit road in front of a willing friend, their headlights pick it out much better than you ever can in daylight. Quite a short run can cover cold to warm, under load and over-run, which has helped me diagnose problems in the past.

Possibly dumb question, but if a turbo lets go is it inevitable that it dumps oil into both hot and cold sides?

no, its now running better than ever, seems to have some residual oil in the silencer to clean out.
I dont recall exactly what the guy in the turbo shop said, but definitely got the impression that all was good to go, him having seen the new turbo and old chra
it is a major job to remove the intercooler, and the garage would want more than the car is worth
it is obvious that the damage was done to the exhaust side of the turbo, so the intercooler should not be affected, no?
Its done 300miles now
But thanks for your insight

it is obvious that the damage was done to the exhaust side of the turbo

You haven't told us that up until this point, you could have saved a lot of pointless conjecture if you had.

I'm still really not sure how an intercooler is a major job after removing and stripping a turbo, it's not even French!

I got no further with this, but have a couple more questions

The smoke from exhaust is mostly when its idling, so;
Could the oil feed to the turbo,create this smoke at idle?

If the PCV/CCV valve is blocked/dirty, would this create a smoky exhaust at idle??

Im now thinking that the turbo is not a problem, possibly too much pressure/blowby from a worn engine is creating the smoke.
Does this sound feasible?

I really need to get the emissions down for an MOT test soon

What does your oil look like - any fuel in the oil when left to settle ? <span style="text-align: center;">I</span>

<span style="text-align: center;"> know of a couple of engines I know well (not Audis) that over fuel smoke at idle would have me looking at injector leak off tests - cheap test. Will probably give an expensive diagnosis that no one wants to receive on an old car. </span>

But then it's only cheap if your engine is of the type you can do a leak off test on without upsetting the fuel rail pressures.

oil looks good- just changed it.
smoke is more greyish -at idle, or under slight load at 1500rpm
Id like to check the injectors and/or compression. Even if its too much to fix it, I want to know where the probleem is.

Dont know exactly what happened with the turbo.
Prior to that i tried mr muscle to clean some carbon out of it

I mean, I'm not an expert but...

Oven cleaner is an old fix for clagged up vanes, that was in the pre-DPF days though.

Grey smoke at idle sounds like oil leak. It's a sort of fixed quantity so when you rev up it gets blown away in the exhaust.  Could be something like valve stems leaking. Burning oil has a nasty acrid smell to it, a bit like burning rubber or chemicals or something. Unburned diesel smoke is sooty and sort of... Feels different in your nose.

if it was valve stem oil seals leaking, how would i diagnose and is it a simple fix?
Or is there an additive to fix it for a while?

I don't know, you'd probably have to rebuild the head to fix them. I think there are additives that claim to be able to fix things like that but who knows if they work.

That's just one of the things that can cause oil to get into the combustion chamber.  Another is worn piston rings.

Some pictures in this video.  Ignore the stuff about vacuum sucking oil in, probably doesn't apply to you.  Plus those examples are horrendous.

thats a good informative video. if all videos were like that...

im not burning any oil.

Stem seals will clear after a few minutes, my C8 smoked like a chimney. Start it up again and it should stay clear but will build up again after an hour or so of sitting.

Grey smoke could be oil or fuel.
On something without a DPF, an experienced nose can easily tell the difference, with a DPF, not so much.

It sounds more like a fuelling issue, but without seeing the vehicle in person, it's pure guesswork.

First rule of remapping is to have your engine running fault free first.  Will the company that supplied the map temporarily put the car back to stock whilst you diagnose the smoking problem?

Remapping just strips out the carefully balanced mapping that keeps your emissions down, we've all notice those modified cars that have clearly been badly mapped with a stinky exhaust and a black sooty arse.  Our fleet at work was all given an 'eco' tune and the Vauxhall's in particular had an acrid smelling exhaust that you'd always notice in the yard.

I had my first van mapped and yes, it made it much quicker, but I'm not doing my current van for the above reasons.

It will smoke at idle when warm,but I drove for an hour,and it was still smoking at idle, so maybe not stem seals.
I could restore the original map.
And it doesnt have a dpf

Diesel smoke smells a bit like candle smoke. Oil smoke is acrid and absolutely horrible.

This stage 1 mod. Is it a box that ypu wire in? Or an actual remap? Those boxes just mess with the rail pressure, potentially causing smog at idle

this is an actual remap, which was done before the turbo blew.

Generic map or  Dyno derived map specific to the outputs of the car ?

Generic maps downloaded off the interwebs can have similar effects to plug in boxes especially on an older car with wear and sensors not reporting accurately./the same as the car the tune was derived on.

How long before turbo blew ? Was it running smoke free prior to turbo blowing ? If so likely a white elephant

I was going to say that smoke can be cause by not enough air/too much fuel, which would be the case under high load but at idle there is likely to always be enough air to burn what little fuel is injected. If it over fuelled, that fuel would still be burned leading to higher revs and then the car would simply reduce injection further to achieve the specified revs.

TBH, even quite "well respected" remaps just switch off a few safeties and over fuel like a MF.

Especially on diesels.

If it over fuelled, that fuel would still be burned leading to higher revs and then the car would simply reduce injection further to achieve the specified revs.

Hence a leak off test. Injectors have a service life. Generally they fail to atomise sufficiently but people dont notice the decline and just live with it. Often though they fail to close and just let fuel through the system which is ejected as smoke - the car doesn't see that fuel being input as it's told the injector to restrict flow but can't get it low enough

Yeah if it's leaking at the wrong point in the cycle that makes sense.

Diesel smoke smells a bit like candle smoke. Oil smoke is acrid and absolutely horrible

Both diesel and engine oil can both cause those types of smoke, as the smoke depends on what's causing it.

Diesel or oil that go through the combustion chamber without being burnt correctly are likely to lead to white/grey smoke, that typically has a quite eye stinging effect. Excess oil will typically cause blue smoke. Excess fuel, or more precisely lack of oxygen, will typically cause excess soot and black smoke.

A competent diesel tech should be able to quite quickly establish which type of smoke it is, but finding the root cause isn't always easy.

Did the fault exist before the turbo failed?
It could be the turbo failing has drawn attention to the smoke, and the smoke was there before the turbo failed, or it could be the turbo failing has damaged something else, or the turbo failing is the symptom of something else.
The fact the car has been remapped, means very few garages will be willing to get involved in diagnostics, as it's just too risky.

checking the injectors with VCDS I found;
Group 013: Idle Stabilization (Injection Quantity Deviation)
0.00 mg/str Injection Quantity Deviation Cyl. 1
-1.88 mg/str Injection Quantity Deviation Cyl. 2
0.80 mg/str Injection Quantity Deviation Cyl. 3
1.06 mg/str Injection Quantity Deviation Cyl. 4

From what I can gather, a deviation of 1mg/str is not good enough, something needs to be done with the injectors.
I did not find a way to do a compression test with vcds
As regards the leakoff tests the cheap adaptors on ebay seem to be for common rail diesels, which mine is not
Its a bit too windy for me to judge the smoke colour and smell

If it's not common rail what is it, 20odd year old PDF?

Don't take this the wrong way but you're a really poor communicator, you've given next to no info, people have speculated, you drop a breadcrumb and repeat.

What car is it?
What year is it?
What engine is it?
What was the history before remap?
What exactly happened after remap?

Without useful info people can't give useful advice.

ok, yes i dont want to give too much info to generalise the problem, was trying to keep things specific to my outlook, i cant deal with evry possibility.i come to a conclusion, then i need to expand on/solve that before i move on
Its a 15yr old a4 2.0tdi 16v pd140, history unknown, 170k miles
Probably should have checked evryting before remap, did mr muscle thing, but something,probably loose bits of carbon went into and wrecked the turbo, so got a new chra and cleaned as best ass i can.the vnt vanes were carbon heavy