2004 Hyundai Accent CRDI Black Smoke When Turbo Kicks In

by Ruby
(India)

My Hyundai accent CRDI (1500cc, 3 cylinders) is normal below 1800 RPM but when turbo kicks in it gives black smoke. Its tolerable normally but when Air Conditioner is switched on, pick up decreases and black smoke is very much noticeable always.
0-100 now takes 31 secs instead of 17sec.
Mileage has dropped.

EGR valves replaced, New Pistons, New Rockers, Cylinder head OK, CAM OK, Fuel Pump OK, Whole exhaust cleaned including Catalytic converter,No over heating, Turbo OK, no error code in computer check.

Just one problem, out of three injectors, one is pouring more diesel than normal but agency mechanic says that it's not real problem. they can replace it for $450 but no guarantee of black smoke stoppage and if once fitted, wont take that back.

Steve Says,

Hi, Ruby! It's good to get a question from India today! As for your question, there are a couple of things that come to mind. First, I do have to say that I do not have experience with this specific car so my suggestions will be rather general, but might help some...hopefully!

The first thing I would check is the condition of the piston rings. You can check this by doing a compression test. If they are worn the test will show lower than normal compression. If the rings are worn they could be letting oil get passed them and burn in the combustion chambers.

Many times this type of problem is caused by leaking turbo seals. The turbo is cooled and lubricated by engine oil and if the seals in the turbo go bad they can cause oil to leak into the incoming air and into the cylinders.

The only thing that does not make complete sense with those two ideas is that your mileage has dropped. Since you do have one leaky injector I'm wondering if there are two things going on. One being the leaky injector causing low gas mileage and the other being the rings or turbo leaking oil into the cylinders.

This is my best guess. I hope it helps. Please post the fix when you know what it is.