Black smoke

[Stu Sheridan]

Hi all, is been a while since I posted on the forum.

Got a bit of an issue with black smoke at low revs when asking for power/acceleration.

The Passat is a 2010tdi DSG with an egr/dpf delete, new MAF, new turbo and actuator and as of today, a new lambda sensor.

It's like the fuel air mix is too rich at low revs, when I put my foot down a little, I get sluggish acceleration and black smoke. This clears once past about 2k rpm. I can use sport mode to minimise the smoke as revs are kept higher.

The smoke can also occur if I allow speed/revs to drop. Say, on long hill, if I throttle off a tiny bit and allow power to drop, before it kicks down it will become smokey.

Fuel consumption, according to the MFD is generally around 45mpg. I commute 60 miles per day, 50 of them on the motorway.

No current fault codes but will check again.

I'm assuming boost is fine having a recon turbo and have had it tested for boost/vac leaks - nothing present.

Any ideas?

And yes, the vast majority of the work mentioned above was done to try to eliminate this problem..... Some of it, like the egr/dpf was to fix other problems.

Sent from my KC-S701 using Tapatalk

[skomedal]

What does BLACK smoke from my exhaust mean?

Black exhaust smoke means the engine is burning too much fuel. The first think you should check is your air-filter and other intake components like sensors, fuel injectors and the fuel-pressure regulator. Other reasons could be a clogged fuel return line. Black smoke is usually the easiest issue to diagnose and fix, but burning unnecessary fuel will definitely affect your fuel economy, so don’t think of avoiding this one to save money, it won’t work.


http://www.autoguide.com/auto-news/2...ust-mean-.html

[Stu Sheridan]

Thanks, it's all good info. Have tried most of the things mentioned, not replaced injectors or or regulator yet though

Sent from my KC-S701 using Tapatalk

[niall campbell]

Hmmmm driving style ?

Diesels in my humble opinion should be driven at slightly higher revs before changing gear, changing down if you need to overtake , the turbo is fitted for a reason

When I change gear, it usually means the revs don't drop below 2,100 rpm

might be too noisy for some

[DMitch16]

Has any work been done on the car prior to your remedial action? Has the EGR / DPF been mapped out correctly as it could be the map is wrong? There are also documented problems with the High Pressure Fuel pumps and regulatory sensors associated with it along with the tank pump and fuel pressure regulators in the circuit. Also when was the diesel filter last changed and was the correct insert used of the 2 types available? Have you read any engine / fuel values using VCDS to see if they are way above / below tolerances? Has the timing belt been replaced recently and the timing rechecked / finely adjusted? Are you using a good quality fuel?

My 2.0 170 DSG Sport (PD engine - 174,000 miles) averages 45mpg on a similar commute as yours (30 miles dual carriage way, 30 miles motorway and 10 miles village / country roads). I don't hold back a lot of the way so it seems your economy is being affected as you should get more from a Common Rail even of the same engine size.

[DMitch16]

Hmmmm driving style ?

Diesels in my humble opinion should be driven at slightly higher revs before changing gear, changing down if you need to overtake , the turbo is fitted for a reason

When I change gear, it usually means the revs don't drop below 2,100 rpm

might be too noisy for some

On a DSG there's no need to drive it at higher revs as the box compensates itself. On a long haul at 70mph my revs hardly go above 2000rpm. During normal cross country driving it gives you high revs when accelerating / kicking down but once you ease off the change downs ease the revs right off. I cruise at 1500 revs on A roads (60mph limit) no problem at all which usually gives me 48/52mpg.

[Stu Sheridan]

Has any work been done on the car prior to your remedial action? Has the EGR / DPF been mapped out correctly as it could be the map is wrong? There are also documented problems with the High Pressure Fuel pumps and regulatory sensors associated with it along with the tank pump and fuel pressure regulators in the circuit. Also when was the diesel filter last changed and was the correct insert used of the 2 types available? Have you read any engine / fuel values using VCDS to see if they are way above / below tolerances? Has the timing belt been replaced recently and the timing rechecked / finely adjusted? Are you using a good quality fuel?

My 2.0 170 DSG Sport (PD engine - 174,000 miles) averages 45mpg on a similar commute as yours (30 miles dual carriage way, 30 miles motorway and 10 miles village / country roads). I don't hold back a lot of the way so it seems your economy is being affected as you should get more from a Common Rail even of the same engine size.

Hi Mitch,

I've basically taken the mask map off to eliminate it from the process, just egr/dpf delete left in.

FYI, a little more smoke is to be expected from a decatted dpf deleted car but not the way this is - its situational not permanent. Low revs with load. When cruising its fine.

Not at all sure about the pump etc but that may be a future line of enquiry.

Timing belt is original and all filters are new and correct.

I've managed 52mpg now and again when pootleing. Usually up around 80mph to return 43-45mpg.

I've not done any recent vdcs logs but plan to do so soon.

I'm thinking I may go to a pump/injector specialist to have things checked...

Sent from my KC-S701 using Tapatalk