2.0TDI Smoking under load - usual suspects checked & VAGCOM graphs for techies

[billnit]

Hi

Been lurking for a while and attempting to self diagnose and fix problem as above but am at the end of my patience and time/money I can spend.

If anyone can offer any advice before i bite the bullet and take into Audi dealer, I'd be really grateful.

Symptoms:
Fine on idle and low revs, however large amount of black smoke from around 2000 rpm all the way to red line. Feels a bit lumpy and underpowered at these higher revs also.

When it started:
Car went into limp mode and nursed back home. Local independent scanned and identified EGR and Cam sensor. Replaced EGR and as it turned out not the sensor (but still charged me for it the robbing b****d).
Noticed smoking a week or so after this. It may have been smoking before, but I cant say for sure.

What I did:
Removed and cleaned: MAF, Air filter/box, anti-shudder valve, EGR and intake manifold along with pipes. All fairly clean but a bit of oil in the pipes.

Scanned with VAG com - no faults other than the cam sensor, which i presume must be a loose connection seeing how was replaced (or not).

Took to separate dealer who found the sensor was originally fitted part and replaced. Now showing no fault codes.
Tried to diagnose smoking and found nothing and suggested top end flush and new oil which he did. Told me turbo was "normal".

£700 lighter, I did the intake pressure test using a compressed air line and a perfectly sized plastic mug with handle removed.

Large hole in the side mounted intercooler. Removed cleaned and repaired intercooler with JB weld. Pressure tested again and no leaks. This must be it i thought, as i confidently went for test drive.

No change :-(

Replaced the air filter and used some fuel additive along with removing the EGR cooler and connecting pipe and giving a good clean. Checked for exhaust leaks.

No change.

Now £1500 in parts and labour and my wife & kids havent seen me for last 3 weekends and have had enough.

Worked out how to plot graphs from VAG COM and these are below. If anyone can shed any light or solve my issue then i will be forever grateful.

I have multitronic, so this are in manual mode, 3rd gear accelerating hard from 2000rpm.

Something doesnt look right around 2100RPM onwards. I am thinking MAF or injectors as pretty much only thing i havent cleaned/replaced/inspected.

Any further data required, please shout...

Thanks

Paul

2145721458214592146021461

[billnit]

No one any ideas on this or am I taking car to main dealers?

[Guest 2]

Have you changed the fuel filter?

Also is it a 140 or 170 as the 170s I'm pretty sure were subject to a recall for injectors (some were).


Sent from my iPhone using Tapatalk

[nevo]

If it was me I would have replaced the maf at first with a genuine one,but I can understand you don't want to throw more money at it in vain.

[billnit]

Thanks both for the replies:

A6_Chris - I did replace the fuel filter. Emptied out and looked clear with no suggestion of oil in the supply.

It's a 140bhp model. I got Audi to check for any recalls outstanding against the VIN and there were no recalls done or required...

Nevo - I am suspecting the MAF also, but as you say replacement original is more money. I was hoping that someone could maybe diagnose as a bad MAF or a good chance of as i would take a chance and spend on that rather than pay Audi £138 for fault finding to be told it was the MAF anyway.

My feeling is that it is the MAF or the injectors, but with no fault codes being logged, and only basic knowledge of VAG-COM/VCDS I am struggling.

Enjoying the learning process but getting a tad frustrating & expensive now.

Booked in this Thursday at Audi, but if anyone has other thoughts, or strong suspicion it is the MAF then i may cancel and just fit the part. Suppose I could always sell it on if not the cause..

Thanks so far...

[a8 tech]

lol maf sensor fitters still haunt the forums lol

smoke test the intake pipes firstly and check fuel balance plus timing and boost pressure

BLACK SMOKE UNDER LOAD = UNMETERED AIR LEAK

[billnit]

a8, thanks for the reply.

I havent smoke tested but have pressure tested the intake system at 5psi and it is sealed. Did have a leak in intercooler initially which was fixed as per original post.

Also my graphs from original post plot boost against specified and looks to be OK but you would be better judge of this.

As for fuel balance I am not sure where I can measure this. I have plotted injection quantity and deviation but thats as far as my VCDS knowledge extends.

I presume that timing check would be manual using the locking tools, rather than any software based check? Would Audi be able to check without having the front of the car off?

Cheers

[nevo]

I fell off the chair laughing.

[billnit]

I fell off the chair laughing.

Am I missing something here?

Seen plenty of discussion on genuine against pattern sensors but not sure what is so amusing....

[nevo]

Not intended for you billnit,sorry.

[a8 tech]

you need to test the intake system under load to check for collapsing pipes and hairline cracks, air leaks down stream of the airmass will cause this issue

make sure the egr is operating spot on as egr is active to 2300 rpm

ensure the the pressure after the tandem pump is ok so no blowpast at the injector seats

drain the fuel filter and poor into a glass

if discoloured leave for 2 hours and check if you have soot clinging to the glass

if you do pressure test the fuel system from the tandem pump

mind you my 1.9 smokes under heavy boost since i had it mapped

just swinging nobs like after 25 years with audi i will just give you a little insight to the findings after dealing with pd's for a while

you must also check if fitted the manifold change over vacuum unit for depleted vacuum or failing to function at 2000 rpm

airmass will fluctuate with egr values hence so many are replaced incorrectly

ask your dealer when was the last time the workshop replaced a airmass on a pd engine and i think you may find its unheard off after for b7 pd

but again a full test with vcds may mislead but a scope will not