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Black smoke on acceleration.

Posted: 11 Apr 2026, 19:10
by DarrenC90
Hi all, thanks for any help in advance.
So 1.9TD Aaz vanny. Replaced head gasket, valve stem seals, injector nozzles (pop tested to within 5bar or each other and 150 bar set) general clean up of everything.

Now after rebuilding the van smokes a bit of black smoke on throttle (constantly when accelerating, nothing on idle or run down)
I’ve started at 0.92mm injection timing. Just gone up to 1mm on the DTI injection timing and still the same.

Any suggestions on where I start?
Further advancing the injection timing?
Anything injector I should be looking at?
Power feels maybe lower than it did before but not massively dis similar (it’s been 4 months in the making so I wonder if this is just getting back into it after winter break!)

Should I have to adjust my fuel screw with new nozzles? They were genuine Bosch ones so I didn’t go cheap!


Stuck abit really, feel like I’m chasing this around. Already pulled injectors out and checked the flame traps were sealing twice.

Any help, much appreciated!

Thanks

Re: Black smoke on acceleration.

Posted: 16 Apr 2026, 21:31
by DarrenC90
Any help on this fellow van folk?
Checked turbo out, awaiting a gauge now.

Any way of double checking injectors are good without removing?
Worried the fresh injector nozzles might be the problem.🤨

Can hit 700 degrees egt’s on a hard run, which is worrying on a not tuned van.

Any suggestions much appreciated!

Thank you

Re: Black smoke on acceleration.

Posted: 23 Apr 2026, 22:19
by DarrenC90
So.. new turbo later and still smoking black smoke! Hooked up a boost gauge to the intake manifold and I can only seem to get the turbo to 8psi no matter how far the wastegate screw is turned in it doesn’t seem to change? Confusing.

Away in it this weekend, so hoping it holds up for the trip 😩

ANY help anyone would be much appreciated. Further advance the timing?
Van starts up fine and seems to run alright otherwise if not maybe a little bit hot.

Please please please help it’s driving me insane! Where do I start next.

Thank you!

Re: Black smoke on acceleration.

Posted: 24 Apr 2026, 04:29
by TwinTurbo
have you checked for and boost leaks? split hoses, damaged vac lines , anything that could weaken the mixture?

Re: Black smoke on acceleration.

Posted: 25 Apr 2026, 13:52
by silverbullet
Diesel though and its overfuelling. A collapsed air intake hose might do it, literally choking the engine before the air filter.

Re: Black smoke on acceleration.

Posted: 25 Apr 2026, 15:29
by davidoft1
pull the air filter out to see if boost pressure increases, if you've rebuilt the injectors and have a worn pump you may need to tweak the fueling down a little on the pump

Re: Black smoke on acceleration.

Posted: 25 Apr 2026, 15:56
by silverbullet
My money is on a mouses nest down the nearside vent

Re: Black smoke on acceleration.

Posted: 25 Apr 2026, 16:26
by davidoft1
silverbullet wrote: 25 Apr 2026, 15:56 My money is on a mouses nest down the nearside vent


My snorkel pipe had collapsed inside

Re: Black smoke on acceleration.

Posted: 26 Apr 2026, 20:00
by silverbullet
OP had reported reduced power and boost is down, reduced air would make for black smoke and it could well be sucking the inlet pipe flat.