Strange (Intermittent) Smoke from exhaust and Rough idling

[Almurray42]

Hi, wondering if anyone has had a similar issue...

Info: A3 8P 2.0TDI Engine Code: CBAB

So this morning driving to work, I noticed as I started the car that it was idling very rough, shaking but didn't feel  like it was a misfire...

Anyway, when driving there was a large amount of white smoke coming from the exhaust, which i'd not had before. Heavier acceleration led to more smoke. I pulled over, turned off the engine and turned it back on. To my surprise, the smoke had stopped and Idle was much better! (Still slightly rough, but maybe unrelated?)

Seemed very odd to me that an engine off/on event made it stop? Took it out for a couple spins and managed to re-create the issue with the smoking, which once again disappeared after a quick engine restart...

I'm Baffled! Appreciate any thoughts/advice!

Al

[Stevey Y]

11 minutes ago, Almurray42 said:

Hi, wondering if anyone has had a similar issue...

Info: A3 8P 2.0TDI Engine Code: CBAB

So this morning driving to work, I noticed as I started the car that it was idling very rough, shaking but didn't feel  like it was a misfire...

Anyway, when driving there was a large amount of white smoke coming from the exhaust, which i'd not had before. Heavier acceleration led to more smoke. I pulled over, turned off the engine and turned it back on. To my surprise, the smoke had stopped and Idle was much better! (Still slightly rough, but maybe unrelated?)

Seemed very odd to me that an engine off/on event made it stop? Took it out for a couple spins and managed to re-create the issue with the smoking, which once again disappeared after a quick engine restart...

I'm Baffled! Appreciate any thoughts/advice!

Al

Hi get it scanned for faults as that will most likely throw up the cause as it sounds like a fuelling issue as it disappears when you stop and restart this reboots it and whatever is sticking open sorts its life out.

Steve.

[Almurray42]

Just now, Stevey Y said:

Hi get it scanned for faults as that will most likely throw up the cause as it sounds like a fuelling issue as it disappears when you stop and restart this reboots it and whatever is sticking open sorts its life out.

Steve.

Thanks Steve

Funnily enough I hadn't actually thought of that - I do have an OBD2 reader, I'll chuck it on in a min with Torque Pro see if anything comes up.. Not sure if i'll need a proper VAG one with VCDS though... We shall see!

Al

[Stevey Y]

1 minute ago, Almurray42 said:

Thanks Steve

Funnily enough I hadn't actually thought of that - I do have an OBD2 reader, I'll chuck it on in a min with Torque Pro see if anything comes up.. Not sure if i'll need a proper VAG one with VCDS though... We shall see!

Al

Hi I think the universal term is Suck it and SEE, VCDS is the the one but OBD Eleven is a close second and about 50-70% cheaper it depends how many VAG vehicles you plan on owning.

Steve.

[Magnet]

Hello Alastair,

Does the white smoke smell of excessive diesel? 

Kind regards,

Gareth. 

[Almurray42]

18 minutes ago, Stevey Y said:

Hi I think the universal term is Suck it and SEE, VCDS is the the one but OBD Eleven is a close second and about 50-70% cheaper it depends how many VAG vehicles you plan on owning.

Steve.

No Fault Codes Found with Torque Pro or Car Scanner Pro...

[Almurray42]

3 minutes ago, Magnet said:

Hello Alastair,

Does the white smoke smell of excessive diesel? 

Kind regards,

Gareth. 

Hi Gareth

That's a good question, i've not actually checked - I Didn't even get out of the car when I Turned engine off/on 🤣

Will check when it next happens!

Al

[Stevey Y]

1 hour ago, Almurray42 said:

Hi Gareth

That's a good question, i've not actually checked - I Didn't even get out of the car when I Turned engine off/on 🤣

Will check when it next happens!

Al

Hi over fuelling manifests itself as white smoke with petrol and black smoke with diesel, engine oil being burnt is bluish smoke, which brings me to the point that the only other thing that would cause this is water in the combustion process, ie head gasket or oil cooler degrading but the thing that rules against this is the fact it stops when you turn it off/on, would suggest getting it plugged in on a more in depth diagnosis platform, see if your local garage will give it the Snap-on treatment for a drink.

Steve.

[Almurray42]

2 hours ago, Stevey Y said:

Hi over fuelling manifests itself as white smoke with petrol and black smoke with diesel, engine oil being burnt is bluish smoke, which brings me to the point that the only other thing that would cause this is water in the combustion process, ie head gasket or oil cooler degrading but the thing that rules against this is the fact it stops when you turn it off/on, would suggest getting it plugged in on a more in depth diagnosis platform, see if your local garage will give it the Snap-on treatment for a drink.

Steve.

Yep, this is why I'm so baffled by the fact it disappears! Will get it on a proper diagnostic machine - but first I have a rather bad oil leak I need to investigate... Will post an update if/when I figure out what's causing this smoke issue!

Thanks

Al

[Harryaudia3]

Hi everyone, 

I am a first time Audi owner and bought my 1.6 petrol 2004 a3 a few weeks ago. (I was very hungover when buying so forgive me for not checking the car better on purchase)

I have an issue that is similar the one above except I have constant rough idling, white smoke constantly when the engine is up to temp. To add to this, I also have hesitation when driving, it also appears to automatically drop or add revs while driving (especially around the 2000rpm mark) My initial thought was it must be an air intake issue, however after replacing the main intake pipe, it is exactly the same. I have purchased Carista but the only fault codes being read are for the heating and air con and body/convenience. The air con codes are: 01592 Air quality sensor (G238) and 00819 High pressure sensor (G65) the fault code for the body/convenience system is: 00352 Clamp 30A. Surely these are separate error codes and wouldn't effect the actual engine? Please if anyone can help point me in the right direction I'm pulling my hair out trying to work this one out...  

[cliffcoggin]

Harry.

Smoke like you describe is an MOT failure. Assuming you bought it from a dealer take it back for a refund or repair.

On the other hand if you bought it privately be prepared for possible high expense, and tell us about mileage and service history.

[Harryaudia3]

Hi Clifford,

Thanks for the reply. 

I bought it privately so no chance of return...

I'm not trained in mechanics at all but am quite happy to give anything a go so hopefully labour costs will be nil to low. 

mileage is between 97000 and 98000, not much service history but the oil is very clean and the air filter looks almost new.

I think it'll need a Cambelt done soon (no damage but 100,000 mark around the corner so should need doing).

My next step is to change the PCV and slowly work my way around the air intake system, was just hoping someone had a similar issue so I at least had something to work off.

My particular model appears to have the PVC built into the oil filler neck, which is weird but I have been told it does happen from time to time.

Any chance the cambelt would cause these issues? I wouldn't have thought so but worth a mention I guess.

 

Regards,

Harry 

 

 

[Harryaudia3]

2 hours ago, Harryaudia3 said:

Hi Clifford,

Thanks for the reply. 

I bought it privately so no chance of return...

I'm not trained in mechanics at all but am quite happy to give anything a go so hopefully labour costs will be nil to low. 

mileage is between 97000 and 98000, not much service history but the oil is very clean and the air filter looks almost new.

I think it'll need a Cambelt done soon (no damage but 100,000 mark around the corner so should need doing).

My next step is to change the PCV and slowly work my way around the air intake system, was just hoping someone had a similar issue so I at least had something to work off.

My particular model appears to have the PVC built into the oil filler neck, which is weird but I have been told it does happen from time to time.

Any chance the cambelt would cause these issues? I wouldn't have thought so but worth a mention I guess.

 

Regards,

Harry 

 

 

I have just this moment found that the clip holding the engine coolant temperature sensor (g62) was warped and letting out some coolant, so I imagine it was also letting air in or out.

I am going to replace the sensor, clip and rubber seal and see if this fixes the issue. 

[cliffcoggin]

That's a good start. Do let us know if it solves the problem.

[Almurray42]

I'm Returning to this thread as I have since resolved the more pressing issues being the Oil leak (Which if you've seen the thread turned out to be an almost full engine rebuild job!) I since had another problem with delayed boost and Limp mode on motorway... Turns out it was the turbo actuator (Suspect Torn Diaphragm) which I've replaced and that problem is resolved.

So this is now one of the final issues I have.

So...The Intermittent issue of what I described previously as a "Rough idle"... To clarify, what it ACTUALLY is: Seems to be excessive shaking of the engine.

To summarise:

SYMPTOMS:

• Whilst Driving, or on engine start, car enters an unstable state INTERMITTENTLY.
• On Idle, Engine is shaking - to the point where you can feel it when sat in the car.
• In this state, at Idle the Revs seem to be stable and aren't fluctuating.
• When Accelerating in this state it can have hesitation and almost be a bit "Jolty" on acceleration.
• When accelerating, lots of light coloured smoke is emitted. 
• Turning engine off/on fixes this fault state 99% of the time.
• No warning lights or ECU Fault codes present. 

Known "Good" parts:

From research, some suggestions are saying to check various things. I have done a lot of work on the car recently so have listed below some parts which I know or am confident are not causing the fault. As I check things, i'll edit the Known Good list.

• Pistons/Rings/Blow-by 
• Turbo/Actuator
• Timing
• Head Gasket

This leaves me with the following train of thought:

As I've recently done a lot of work in the engine, I'm confident that the issue will lie with some sort of ancillary.. Could it be:

Something in the Vacuum system?

EGR related?

Swirl flap related?

CCV?

Fuel pressure regulator?

Injectors?

Fuel filter?

Not really sure where to go next. What's getting me is the fact that this can be fixed by an Engine on/off.

[Stevey Y]

7 hours ago, Almurray42 said:

I'm Returning to this thread as I have since resolved the more pressing issues being the Oil leak (Which if you've seen the thread turned out to be an almost full engine rebuild job!) I since had another problem with delayed boost and Limp mode on motorway... Turns out it was the turbo actuator (Suspect Torn Diaphragm) which I've replaced and that problem is resolved.

So this is now one of the final issues I have.

So...The Intermittent issue of what I described previously as a "Rough idle"... To clarify, what it ACTUALLY is: Seems to be excessive shaking of the engine.

To summarise:

SYMPTOMS:

• Whilst Driving, or on engine start, car enters an unstable state INTERMITTENTLY.
• On Idle, Engine is shaking - to the point where you can feel it when sat in the car.
• In this state, at Idle the Revs seem to be stable and aren't fluctuating.
• When Accelerating in this state it can have hesitation and almost be a bit "Jolty" on acceleration.
• When accelerating, lots of light coloured smoke is emitted. 
• Turning engine off/on fixes this fault state 99% of the time.
• No warning lights or ECU Fault codes present. 

Known "Good" parts:

From research, some suggestions are saying to check various things. I have done a lot of work on the car recently so have listed below some parts which I know or am confident are not causing the fault. As I check things, i'll edit the Known Good list.

• Pistons/Rings/Blow-by 
• Turbo/Actuator
• Timing
• Head Gasket

This leaves me with the following train of thought:

As I've recently done a lot of work in the engine, I'm confident that the issue will lie with some sort of ancillary.. Could it be:

Something in the Vacuum system?

EGR related?

Swirl flap related?

CCV?

Fuel pressure regulator?

Injectors?

Fuel filter?

Not really sure where to go next. What's getting me is the fact that this can be fixed by an Engine on/off.

Hi Al could be the engine mounts as they are Hydro bushes these normally play up when they start loosing oil I know mine did check them out, white smoke is normally an air leak.

Steve.

[Almurray42]

37 minutes ago, Stevey Y said:

Hi Al could be the engine mounts as they are Hydro bushes these normally play up when they start loosing oil I know mine did check them out, white smoke is normally an air leak.

Steve.

I'm certain it's not the mounts. The Smoke and rough running is 100% linked. Engine off/on stops Both (Have even done so whilst driving, clutch in, engine off/on and clutch out temporarily stops it)

Might need to do more digging! Maybe see if I can get some monitors logging whilst driving and capture some differences in the monitors...

 

[cliffcoggin]

Alaster.

This may seem an odd question but how old is the battery? Intermittant electronic faults can sometimes be caused by a battery that is apparently fine in terms of starting the engine and powering the lights and windows etc, but has a defect that interferes with the correct operation of the ECU.

[Almurray42]

On 8/11/2023 at 11:37 AM, cliffcoggin said:

Alaster.

This may seem an odd question but how old is the battery? Intermittant electronic faults can sometimes be caused by a battery that is apparently fine in terms of starting the engine and powering the lights and windows etc, but has a defect that interferes with the correct operation of the ECU.

Not a Bad shout Cliff, thanks. I will get the battery tested by Halfrauds think they do a "Free battery health check" 

Voltage is fine on it though.

 

In other news, the Mrs was drivingl today and EML came on!

Got a Code P2103

"Throttle actuator control motor(TAC) - Circuit High"

First time I've ever been glad to see the Engine Light! Gives me something to start looking at 🙂

 

Will do some research on this and update.. any known common faults with these I should know about?

 

Thanks again

Al

[Stevey Y]

17 hours ago, Almurray42 said:

Not a Bad shout Cliff, thanks. I will get the battery tested by Halfrauds think they do a "Free battery health check" 

Voltage is fine on it though.

 

In other news, the Mrs was drivingl today and EML came on!

Got a Code P2103

"Throttle actuator control motor(TAC) - Circuit High"

First time I've ever been glad to see the Engine Light! Gives me something to start looking at 🙂

 

Will do some research on this and update.. any known common faults with these I should know about?

 

Thanks again

Al

Hi Al thats nailed it if the throttle butterfly is sticking that would be your air leak [white smoke], take it off and  try cleaning it I bet the butterfly is covered in black crud the circuit high bit is where its using all the power within its operating band to move the butterfly, which means it can't easily reach its idle protocol and will then stick open, worth having the gearbox cover off to check for broken gear teeth as they are made of nylon.

Steve.

[Almurray42]

59 minutes ago, Stevey Y said:

Hi Al thats nailed it if the throttle butterfly is sticking that would be your air leak [white smoke], take it off and  try cleaning it I bet the butterfly is covered in black crud the circuit high bit is where its using all the power within its operating band to move the butterfly, which means it can't easily reach its idle protocol and will then stick open, worth having the gearbox cover off to check for broken gear teeth as they are made of nylon.

Steve.

Sooo

 

Throttle body is still fairly clean from when I de-coked it all.. (See below)

 

Popped the cover off and looks in pretty good nick inside!

Tested the full actuation with my Power supply.. Everything appears to be working normally?

 

Seems unlikely, but wonder if it's a wiring/loom issue? OR actually what Cliff mentioned about a potential battery fault causing the ECU to somehow operate irregularly...

The Saga continues...

Al

 

[cliffcoggin]

On 8/12/2023 at 5:05 PM, Almurray42 said:

Not a Bad shout Cliff, thanks. I will get the battery tested by Halfrauds think they do a "Free battery health check" 

Voltage is fine on it though.

A simple voltage check will not reveal an internal fault in the battery. It needs a deep discharge test which involves measuring the voltage while drawing a heavy current. I don't know if Halfords do that.

[Almurray42]

3 minutes ago, cliffcoggin said:

A simple voltage check will not reveal an internal fault in the battery. It needs a deep discharge test which involves measuring the voltage while drawing a heavy current. I don't know if Halfords do that.

Yes, agreed. I don't have the capacity to test this without doing a lot of research first on limits and Continuous discharge thresholds etc. Having a quick look at the info on Halfords, they do it at their autocentre and hook it up to a machine which apparently tests various things including "Cranking capability" which is essentially a load stress test... As it's free I'll give it a go.

Going back to the Throttle body though, I did manage to get it to stick a couple of times when manually actuating it, so I've got a second hand eBay one on the way to pop on and try out. (Was only £35 so worth eliminating I think!)

Al

[AJSA]

My Audi A5 had once smoke and vibration and switched off and on not sorting out happened while slowing down in car park 5miles / hour

then tried hard on gas for a few minutes all clear

send to Audi for a check up , the technician could not find any fault !!!! 
 

it drives like normal again . Any suggestions I should be looking out for ?