Your opinion on diesel smoke problem on 3.0CDTi

[Celes]

I believe I asked the same question before, but never got an answer...maybe cos no one knows the 3.0 well enough

I shall begin by explaining what was "wrong" with my old 3.0CDTi with 160k+ miles.
That thing (let her rest in peace wherever she might be ) had a NEW turbo fitted, NEW EGR valve, injectors with 50k miles, cleaned boost sensor, intercooler and hoses in order,...decat...
However, it was still a bit down on power. I suspected a bad MAF sensor, but back to that later...

The main problem was that it smoked whenever I revved it in neutral. It was so bad that for a moment I couldn't see behind, BUT if I redlined it in any gear it barely put out any smoke.

I then cleaned what I thought was the culprit of the smoke and drop in performance, but it only helped with the power for a while, then it got sluggish again after a few miles...shot sensor I suppose.


Now to my current car. Mileage around 120k, original injectors, original EGR, original fuel pump, turbo with around 30k, intercooler and hoses in order, with catalytic converter still fitted,...
It pulls like a tank, with no apparent power loss anywhere in the rev range apart from a slight delay when I accelerate through 2600rpm.

Despite everything I tried with this engine, Millers or 2-stroke oil, it still smokes if revved in neutral. It won't smoke if ragged through the gears, solved that with the additives and an "Italian tune-up" in Germany.


So, both cars behave the same way but each has different history of repairs.


Alright chaps, need your suggestions now, because every garage I went to was stumped by this

[Celes]

Afternoon bump

[m8internet]

The main problem was that it smoked whenever I revved it in neutral. It was so bad that for a moment I couldn't see behind, BUT if I redlined it in any gear it barely put out any smoke

Mine does that too

I took my car back when I had it for a few days to the dealership, no fault could be found and it was logged
On the second visit they apparently had a similar report from another owner, and so considered it as normal

At the first MoT the tester advised me it was going to fail on emissions
However it returned a 0.00 to which he thought his equipment was faulty, so he then tried it on another diesel and but that returned a higher reading
He then retested mine, a BIG cloud of smoke, but again 0.00

On the second MoT, he advised he had since seen another Y30DT and confirmed it appears to be normal, "oh this is the engine that blows tons of smoke on the emissions test but gives a nil result"

When my SCV was being replaced I asked the area engineer about this and if there was any solution, again he advised it was normal and it was due to the high change in revs which wouldn't normally occur during normal driving

[Celes]

I SURPRISINGLY passed the emission's test with flying colours. I've seen another Y30DT barely smoking in neutral. That's why I think there might be something wrong...

[diesel dog]

It seems that it's overfuelling when not under load. Could be slightly dodgy MAP or MAF sensor.

[Celes]

Don't think it's the MAP sensor as I cleaned that on my old 3.0 and it still smoked.

[diesel dog]

The difference between your engine smoking and not smoking seems to be that in one circumstance it's under load and in the other circumstance it's not. So I would have to say that it's got to be a sensor that can detect load. It could still be the MAP sensor if it's started to err towards the overfuelling end of its parameters. Likewise the MAF sensor.

Try disconnecting the MAP or MAF sensor and see if it doesn't smoke in neutral with either one disconnected.

[m8internet]

Mine has been doing it since 10K miles / November 2006, it's just a visible cloud of smoke, which is quite normal for a diesel
I knew at the first MoT, two years later, it would do it
As above, I asked again in January 2009 about it and was advised "it is normal with the Y30DT"

[diesel dog]

Mine has been doing it since 10K miles / November 2006, it's just a visible cloud of smoke, which is quite normal for a diesel
I knew at the first MoT, two years later, it would do it
As above, I asked again in January 2009 about it and was advised "it is normal with the Y30DT"

Mine doesn't do it. Gets through MOT opacity test no problem....but then, so does yours and Celes's.

[m8internet]

Mine doesn't do it

Are you sure?
I asked someone else with a Y30DT, also claimed "mine doesn't do it", but when I showed them that after idling to warm and then booting it, a large amount of smoke was produced
The trick is to leave the car idling from startup

I recently noticed a similar issue when running at low revs for a long time, and then booting it; the car behind me disappeared out of view in a cloud of smoke