1.8Tfsi - black smoke when pulling away following remap

[Descarl]

Hi all

I recently purchased a 2010 A5 1.8Tfsi and I have to say I absolutely love the car.  I had it remapped yesterday and now I get black smoke from the exhaust when pulling away or revving hard.  The smoke is only when I pull away or start revving and doesn't persist if I keep the revs high.  If I sit in the car in my driveway and continually rev press the throttle to rev and release the car I can see a soot deposit forming on the drive and my exhaust tips are covered in dry soot.  When I noticed it I called the guy that did the remap (it's a generic map rather than using a rolloing road) and he came back to take a look at the car and I also changed plugs and filters just in case.

Anyway the guy came back and plugged his diagnostic tools in to the car and the MAF was showing on 0.75 on VCDS (didn't really change when revving) and a system leak error (sorry can't remember the code) somewhere.  When I unplugged the MAF the reading went up to around 2.45 but immediately went back to around 0.75.  I then got him the return the car to the OEM map (it wasn't smoking prior to the remap) but if anything it was worse with the OEM map.  The engine is running fine and there's no loss of power at any point, I haven't really had any time to see if the mpg has been effected.

I assume that the remap has shown up an issue that was already there with the engine or caused something to go over the edge and fail which is now causing the smoke which I believe in unburnt fuel.  Does anyone have any ideas of what could be the issue, I'm planning on starting by replacing the MAF (due to the low readings) and if that doesn't fix things move on to the coil packs and injectors (I'm planning on putting an injector cleaner through the system to see if it helps but I don't hold out much hope.  I'm hoping it's not the rings but there is no blue in the smoke at all so I don't believe any oil is burning off.

Anyway apologies for the long post, any advice would be greatly appreciated as I really love this car and just want it to run as good as it looks

Carl 

[Descarl]

9 hours ago, Descarl said:

Hi all

I recently purchased a 2010 A5 1.8Tfsi and I have to say I absolutely love the car.  I had it remapped yesterday and now I get black smoke from the exhaust when pulling away or revving hard.  The smoke is only when I pull away or start revving and doesn't persist if I keep the revs high.  If I sit in the car in my driveway and continually rev press the throttle to rev and release the car I can see a soot deposit forming on the drive and my exhaust tips are covered in dry soot.  When I noticed it I called the guy that did the remap (it's a generic map rather than using a rolloing road) and he came back to take a look at the car and I also changed plugs and filters just in case.

Anyway the guy came back and plugged his diagnostic tools in to the car and the MAF was showing on 0.75 on VCDS (didn't really change when revving) and a system leak error (sorry can't remember the code) somewhere.  When I unplugged the MAF the reading went up to around 2.45 but immediately went back to around 0.75.  I then got him the return the car to the OEM map (it wasn't smoking prior to the remap) but if anything it was worse with the OEM map.  The engine is running fine and there's no loss of power at any point, I haven't really had any time to see if the mpg has been effected.

I assume that the remap has shown up an issue that was already there with the engine or caused something to go over the edge and fail which is now causing the smoke which I believe in unburnt fuel.  Does anyone have any ideas of what could be the issue, I'm planning on starting by replacing the MAF (due to the low readings) and if that doesn't fix things move on to the coil packs and injectors (I'm planning on putting an injector cleaner through the system to see if it helps but I don't hold out much hope.  I'm hoping it's not the rings but there is no blue in the smoke at all so I don't believe any oil is burning off.

Anyway apologies for the long post, any advice would be greatly appreciated as I really love this car and just want it to run as good as it looks

Carl 

Some further information the above only seems to happen when the engine is thoroughly up to temperature so I wonder whether something is breaking down when the engine is running warm.

[Magnet]

Hello Carl,

I’m not saying this is the offending component with your car, but faulty coolant temperature sensors can give similar issues. They work on the principle that they sense the coolant temperature and signal the ECU to set the correct mixture for that temperature - rich when cold, lean when hot. 

If they fail, they do so to an arbitrary resistance value which can result in over rich mixtures when hot, and indeed too weak when cold. 

Does the car start instantly from cold? 

Kind regards,

Gareth. 

[Descarl]

10 hours ago, Magnet said:

Hello Carl,

I’m not saying this is the offending component with your car, but faulty coolant temperature sensors can give similar issues. They work on the principle that they sense the coolant temperature and signal the ECU to set the correct mixture for that temperature - rich when cold, lean when hot. 

If they fail, they do so to an arbitrary resistance value which can result in over rich mixtures when hot, and indeed too weak when cold. 

Does the car start instantly from cold? 

Kind regards,

Gareth. 

Hi Gareth

Thanks for the reply, the car starts on the button and runs perfectly.  It's weird though but the smoke only appears initially when revving, if you keep the revs high the smoke goes away.  It's almost like the car is running rich initially and then catches up with itself and sorts the fuelling out.  I'm not sure if an issue with the coolant temperature sensor would effect the way the temp is reported in the car but as far as I car see it gets to mid-way on the gauge and is then solid there whether at a standstill or driving.  I'm starting to think the coil packs are starting to play up when the engine heats up, they've been on the car a couple of years and I've read somewhere they could start breaking done when they get hot.

I'm getting it smoke tested next week to see if there's a vacuum leak somewhere as VCDS reported a leak and if that doesn't doesn't find anything I'll replace the MAF as that seemed to be reporting really low values.  I will though keep in mind your suggestion, and definately add it to the list of possibles:-)

I've also got a Carista OBD somewhere so I'll dig that out and see if there are any fault codes, other than mentioned above, being reported that could point me the right direction.

Anyway thanks again for the feedback, hopefully I can sort this out quickly and enjoy the car!  How's Cardiff by the way, a Valleys boy originally myself but spent a lot of time in Cardiff as well as going to University there!

Carl

[Magnet]

Hello Carl,

The coolant temperature sensor will not affect the actually running temperature of the coolant  i.e. the cooling system works as it should do and the operating temperature will stay at normal when up to the operating temperature. 

What this sensor does is to simply monitor this temperature and signal it’s varying resistance value to control the fuel mixture. 

Coil packs? I would expect the that if these were suspect, you would was experience missing associated with the black smoke. 

Injector issues?? 

Kind regards,

Gareth.