2015 E250 coupe, 2.1 diesel. Puff of smoke under heavy throttle

[MarkSimp]

Hi all,
Im wondering if anyone can help as I've been trying to solve this for 2 weeks now.
My car failed it's mot over emissions. I get a little puff of smoke when the tester gives it a heavy rev.

I don't have any lights... And therefore no codes.
Dpf reports 28% full, 0 ash, 0 soot.
It runs perfectly! I haven't felt any loss in power, She flys! And I get 45>50mpg (that's how much I usually get over the past 4 years).

2 oil changes, tank full of V-power, engine flush and a decarbonisation.
While taking the silver pipe off that goes from the egr into the intake (just after throttle) to clean it, I found that one of the bolts was lose. The pipe was covered in wet crud. Cleaned it all and put it back on with new gaskets. No change.

I've been told that it could be injector leak or a boost leak. Wouldn't that throw an engine code or a loss in mpg?

Going to get a leak down test done on the injectors but this one really has me really puzzled!

Anyone had similar??
Thanks
Mark

 

[ManofKent]

Hi Mark

What colour is the puff of smoke?

White - can be unburned fuel
Black - combustion problems.

 

[MarkSimp]

Hi Mark

What colour is the puff of smoke?

White - can be unburned fuel
Black - combustion problems.

Hi, thanks for the help.
It's black. It's not enough to see from inside the car, I have to get someone to step on the pedal and look from behind.
I also don't lose any coolant or oil. Or at least not enough to notice between my yearly services (per year, 8k > 10k miles)

 

[ALFAitalia]

A similar problem on my car was indeed a boost leak....a small split in the hose between the intercooler and the intake manifold. This also gave no fault codes. I would not have known about if at all if it was not that the rear bumper started to get dirty around the exhaust. There was no obvious hissing with the bonnet up until I got my son to rev it while under the car.... to reveal a small 2 inch split that opened under higher boost pressures.

 

[Trickythemerc]

I had a very similar problem, sooty exhaust smoky under load Etc. No codes but the EML would blink at me now and then, I had a broken hose clip and the boost pipe had worked loose on the nose of the turbo. New hose clip sorted it out.

 

[MarkSimp]

Thanks guys.
I did notice every now and again I would wash the car (I do it every weekend) and there would be a small amount of black on the tips.
You've been a great help. I will take off the undercovers off again and check in boost hoses. Fingers crossed!

 

[DSM10000]

Thanks guys.
I did notice every now and again I would wash the car (I do it every weekend) and there would be a small amount of black on the tips.
You've been a great help. I will take off the undercovers off again and check in boost hoses. Fingers crossed!

You say no EML so no codes, but have you had the car scanned for codes?

Just because there isn't a current warning light doesn't mean that there are no codes stored.

 

[MarkSimp]

You say no EML so no codes, but have you had the car scanned for codes?

Just because there isn't a current warning light doesn't mean that there are no codes stored.

Hi,
Yes, I have an icarsoft scanner. Checked multiple times. Only ones I've had are from when I do the service. I like to crank it over a little on the starter just to get the filter primed up.

 

[MarkSimp]

Could be corrosion on the output from the turbos to pipe. Only had the one pipe off so far but it was a bit wet around here.
Nothing in the pipe tho

 

[MarkSimp]

Cleaned the 2 pipes inside and out. Twisted them around and couldn't see any cracks.
Cleaned off the corrosion and refitted.
No visible damage to the intercooler and it is still smoking on WOT.
Need for it to stop raining and get under it to inspect the throttle side of the pipes while someone mashes the pedal.

I wonder if covering it all in chalk or talcum powder then looking for disturbance would work

 

[geoffus]

Dpf reports 28% full, 0 ash, 0 soot.

That's like brand new DPF readings, there should be some ash, how many miles and has it had a DPF delete and that's why it smokes ?

 

[MarkSimp]

That's what the scanner said. Car has done 120k now. Had it since 84k

 

[MarkSimp]

OK, so I still haven't manged to get to the bottom of this yet.
I decided to do a forced dpf regen and the car instantly went into limp mode (DPF codes, mechanical error). The icarsoft hadn't even started the regen yet, it went into limp as soon as I cranked it.
I took the dpf off and it had collapsed!
I thought I would try a dpf delete as the smoke must have been the collapse. Well, that didn't work.

I got a second dpf from a stripped car and had it professionally cleaned out. The said it was in very good condition.
In the mean time I though it must still be an issue as this would be why the filter collapsed in the first place.

I checked the intercooler pipework again.
I replaced the o2 sensor.
Took off the injectors and got them tested and cleaned up. There's no issues with them, all in spec and running evenly.
She still smokes.
I put the dpf back on and rebooked just to see if it would pass.
Failed, too much smoke still coming through!
Over the weekend I've removed EGR (nothing wrong, slight corrosion leading to edge of egr and gasket) but it isn't jammed up and feels smooth opening by hand.
removed intake flap, mixer and intercooler hose > intake flap and intake manifold to clean them. The second bolt from bottom front was only finger tight but there's no evidence it was leaking, no oil on the block etc.
No cracks at the weak spot in the middle of the manifold, flaps all ok and working.

It took me about 3 hours to clean all the gunk off of everything!

I have a complete new gasket set with various pipes I want to replace and another fuel filter housing. Going to put her all back together at the weekend.

If she still smokes I'm going to take her into the local Merc inde. This will be the first time a car has beaten me but I'm out of ideas.